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2022-09-06
2022精心整理了100+Python字符串常用操作，收藏备用（python基础字符串）
2022精心整理了100+Python字符串常用操作，收藏备用（python基础字符串）
# 精心整理了100+Python字符串常用操作，收藏备用
字符串作为平时使用最多的数据类型，其常用的操作我们还是很有必要熟记于心的，本文整理了多种字符串的操作的案例，还是非常用心， **
全文篇幅巨长，建议收藏再看 **
* 在 Python 中获取字符的位置
* Python字符串替换多次出现
* 在索引后找到第一次出现的字符
* 在 Python 中将字符串更改为大写
* 在 Python 中拆分具有多个分隔符的字符串
* 在 Python 中获取字符串的大小
* Python中的字符串比较 is vs ==
* 每当数字与非数字相邻时，Python 正则表达式都会添加空格
* 在 Python 中仅按第一个空格拆分字符串
* 在Python中将字符串中的一些小写字母更改为大写
* 将字符串拆分为具有多个单词边界分隔符的单词
* 检查一个字符串在 Python 中是否具有相同的字符
* 在多个分隔符或指定字符上拆分字符串
* 将一个字符串附加到另一个字符串
* 在 Python 中遍历字符串
* 从 Python 中的字符串中去除标点符号
* 将列表转换为字符串
* 将 JSON 转换为字符串
* 对字符串列表进行排序
* 在 Python 中检查字符串是否以 XXXX 开头
* 在 Python 中将两个字符串网格或交错在一起的不同方法
# 字符串切片操作
test = "Python Programming"
print("String: ", test)
# First one character
first_character = test[:1]
print("First Character: ", first_character)
# Last one character
last_character = test[-1:]
print("Last Character: ", last_character)
# Everything except the first one character
except_first = test[1:]
print("Except First Char.: ", except_first)
# Everything except the last one character
except_last = test[:-1]
print("Except First Char.: ", except_last)
# Everything between first and last two character
between_two = test[2:-2]
print("Between two character: ", between_two)
# Skip one character
skip_one = test[0:18:2] # [start:stop:step]
print("Skip one character: ", skip_one)
# Reverse String
reverse_str = test[::-1]
print("Reverse String: ", reverse_str)
Output:
String: Python Programming
First Character: P
Last Character: g
Except First Char.: ython Programming
Except First Char.: Python Programmin
Between two character: thon Programmi
Skip one character: Pto rgamn
Reverse String: gnimmargorP nohtyP
# 检查字符串是否为空
import re
from collections import Counter
sentence = 'Canada is located in the northern part of North America'
# Example I
counter = len(re.findall("a", sentence))
print(counter)
# Example II
counter = sentence.count('a')
print(counter)
# Example III
counter = Counter(sentence)
print(counter['a'])
Output:
Empty
Empty
Empty
# 计算字符串中字符出现次数的多种方法
import re
from collections import Counter
sentence = 'Canada is located in the northern part of North America'
# Example I
counter = len(re.findall("a", sentence))
print(counter)
# Example II
counter = sentence.count('a')
print(counter)
# Example III
counter = Counter(sentence)
print(counter['a'])
Output:
# 将 String 变量转换为 float、int 或 boolean
# String to Float
float_string = "254.2511"
print(type(float_string))
string_to_float = float(float_string)
print(type(string_to_float))
# String to Integer
int_string = "254"
print(type(int_string))
string_to_int = int(int_string)
print(type(string_to_int))
# String to Boolean
bool_string = "True"
print(type(bool_string))
string_to_bool = bool(bool_string)
print(type(string_to_bool))
Output:
class 'str'
class 'float>
class 'str'
class 'int'
class 'str'
class 'bool'
# 向字符串填充或添加零的不同方法
num = 7
print('{0:0>5d}'.format(num)) # left
print('{0:0<5d}'.format(num)) # right
print('{:05d}'.format(num))
print("%0*d" % (5, num))
print(format(num, "05d"))
temp = 'test'
print(temp.rjust(10, '0'))
print(temp.ljust(10, '0'))
Output:
00007
70000
00007
00007
00007
000000test
test000000
# 去掉字符串中的 space 字符
string_var = " \t a string example\n\t\r "
print(string_var)
string_var = string_var.lstrip() # trim white space from left
print(string_var)
string_var = " \t a string example\t "
string_var = string_var.rstrip() # trim white space from right
print(string_var)
string_var = " \t a string example\t "
string_var = string_var.strip() # trim white space from both side
print(string_var)
Output:
a string example
a string example
a string example
a string example
# 生成N个字符的随机字符串
import string
import random
def string_generator(size):
chars = string.ascii_uppercase + string.ascii_lowercase
return ''.join(random.choice(chars) for _ in range(size))
def string_num_generator(size):
chars = string.ascii_lowercase + string.digits
return ''.join(random.choice(chars) for _ in range(size))
# Random String
test = string_generator(10)
print(test)
# Random String and Number
test = string_num_generator(15)
print(test)
Output:
acpPTojXet
qmpah72cjb83eqd
# 以不同的方式反转字符串
test_string = 'Python Programming'
string_reversed = test_string[-1::-1]
print(string_reversed)
string_reversed = test_string[::-1]
print(string_reversed)
# String reverse logically
def string_reverse(text):
r_text = ''
index = len(text) - 1
while index >= 0:
r_text += text[index]
index -= 1
return r_text
print(string_reverse(test_string))
Output:
gnimmargorP nohtyP
gnimmargorP nohtyP
gnimmargorP nohtyP
# 将 Camel Case 转换为 Snake Case 并更改给定字符串中特定字符的大小写
import re
def convert(oldstring):
s1 = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', oldstring)
return re.sub('([a-z0-9])([A-Z])', r'\1_\2', s1).lower()
# Camel Case to Snake Case
print(convert('CamelCase'))
print(convert('CamelCamelCase'))
print(convert('getHTTPResponseCode'))
print(convert('get2HTTPResponseCode'))
# Change Case of a particular character
text = "python programming"
result = text[:1].upper() + text[1:7].lower() \
+ text[7:8].upper() + text[8:].lower()
print(result)
text = "Kilometer"
print(text.lower())
old_string = "hello python"
new_string = old_string.capitalize()
print(new_string)
old_string = "Hello Python"
new_string = old_string.swapcase()
print(new_string)
Output:
camel_case
camel_camel_case
get_Programming
kilometer
Hello python
hELLO pYTHON
# 检查给定的字符串是否是 Python 中的回文字符串
import re
Continue = 1
Quit = 2
def main():
choice = 0
while choice != Quit:
# Display the menu.
display_menu()
# Constant to assume string is Palindrome
is_palindrome = True
# Get the user's choice.
choice = int(input('\nEnter your choice: '))
# Perform the selected action.
if choice == Continue:
line = input("\nEnter a string: ")
str_lower = re.sub("[^a-z0-9]", "", line.lower())
for i in range(0, len(str_lower)//2):
if str_lower[i] != str_lower[len(str_lower) - i - 1]:
is_palindrome = False
if is_palindrome:
print(line, "is a palindrome")
else:
print(line, "is not a palindrome")
else:
print('Thank You.')
def display_menu():
print('\n*******MENU*******')
print('1) Continue')
print('2) Quit')
main()
Output:
*******MENU*******
1) Continue
2) Quit
Enter your choice: 1
Enter a string: A dog! A panic in a pagoda!
A dog! A panic in a pagoda! is a palindrome
*******MENU*******
1) Continue
2) Quit
Enter your choice: 1
Enter a string: Civic
Civic is a palindrome
*******MENU*******
1) Continue
2) Quit
Enter your choice: 1
Enter a string: Python vs Java
Python vs Java is not a palindrome
*******MENU*******
1) Continue
2) Quit
Enter your choice: 2
Thank You.
# 检查字符串是否以列表中的一个字符串结尾
str_list = ['aaa', 'bbb', 'ccc', 'ddd'] # list of items
str_test = 'testccc' # string need to test
for str_item in str_list:
if str_test.endswith(str_item):
print("found")
break # loop ends when result found
else:
print("not found")
Output:
not found
not found
found
# 在字符串中应用查找模式
import re
s1 = 'abccba'
s2 = 'abcabc'
s3 = 'canadajapanuaeuaejapancanada'
p = '123321'
def match(s, p):
nr = {}
regex = []
for c in p:
if c not in nr:
regex.append('(.+)')
nr[c] = len(nr) + 1
else:
regex.append('\\%d' % nr[c])
return bool(re.match(''.join(regex) + '#39;, s))
print(match(s1, p))
print(match(s2, p))
print(match(s3, p))
Output:
True
False
True
# 如果是 Python 中的反斜杠，则删除最后一个字符
x = 'Canada\\'
print(x.rstrip('\\'))
Output:
Canada
# 在Python中拆分字符串而不丢失拆分字符
import re
string = 'canada-japan-india'
print(re.split(r'(\-)', string))
Output:
['canada', '-', 'japan', '-', 'india']
# 从字符串 Python 中提取大写和小写字符
string = "asdfHRbySFss"
uppers = [l for l in string if l.isupper()]
print (''.join(uppers))
lowers = [l for l in string if l.islower()]
print (''.join(lowers))
Output:
HRSF
asdfbyss
# 如何在 Python 中比较字符串的索引是否相等
myString = 'AAABBB'
for idx, char in enumerate(myString, ):
if idx + 1 == len(myString):
break
if char == myString[idx + 1]:
print(idx, char, myString[idx + 1])
Output:
0 A A
1 A A
3 B B
4 B B
# 在每个第 4 个字符上添加空格
string = 'Test5412Test8745Test'
print([string[i:i + 4] for i in range(0, len(string), 4)])
Output:
['Test', '5412', 'Test', '8745', 'Test']
# 在 Python 中以多行方式连接字符串
str1 = "This is a demo string"
str2 = "This is another demo string"
strz = ("This is a line\n" +
str1 + "\n" +
"This is line 2\n" +
str2 + "\n" +
"This is line 3\n")
print(strz)
Output:
This is a line
This is a demo string
This is line 2
This is another demo string
This is line 3
# 在 Python 中将多个变量附加到列表中
volumeA = 100
volumeB = 20
volumeC = 10
vol1 = []
vol2 = []
vol1.extend((volumeA, volumeB, volumeC))
vol2 += [val for name, val in globals().items() if name.startswith('volume')]
print(vol1)
print(vol2)
Output:
[100, 20, 10]
[100, 20, 10]
# 将字符串拆分为 Python 中的字符列表
s = 'canada'
l = list(s)
print(l)
Output:
['c', 'a', 'n', 'a', 'd', 'a']
# 如何在 Python 中小写字符串
text = ['Canada', 'JAPAN']
text = [txt.lower() for txt in text]
print(text)
Output:
['canada', 'japan']
# 通过多个标点符号分割字符串
import re
s = 'a,b,c d!e.f\ncanada\tjapan&germany'
l = re.split('[?.,\n\t&! ]', s)
for i in l:
print(i)
Output:
a
b
c
d
e
f
canada
japan
germany
# Python 字符串填充
lines_of_text = [
(123, 5487, 'Testing', 'Billy', 'Jones'),
(12345, 100, 'Test', 'John M', 'Smith')
]
for mytuple in lines_of_text:
name = '{}, {}'.format(mytuple[4], mytuple[3])
value = '#39; + str(mytuple[1])
print('{name:<20} {id:>8} {test:<12} {value:>8}'.format(
name=name, id=mytuple[0], test=mytuple[2], value=value)
)
Output:
Jones, Billy 123 Testing $5487
Smith, John M 12345 Test $100
# 在 Python 中检查两个字符串是否包含相同的字符
str1 = 'caars'
str2 = 'rats'
str3 = 'racs'
print(set(str1)==set(str2))
print(set(str1)==set(str3))
Output:
False
True
# 在 Python 中查找给定字符串中的整个单词
def contains_word(s, w):
return (' ' + w + ' ') in (' ' + s + ' ')
result = contains_word('those who seek shall find', 'find')
print(result)
result = contains_word('those who seek shall find', 'finds')
print(result)
Output:
True
False
# 查找所有出现的子字符串
import re
aString = 'this is a string where the substring "is" is repeated several times'
print([(a.start(), a.end()) for a in list(re.finditer('is', aString))])
Output:
[(2, 4), (5, 7), (38, 40), (42, 44)]
# 在 Python 中去除所有开头在Python中的正斜杠上拆分字符串和结尾标点符号
from string import punctuation
s = '.$958-5-Canada,#'
print(s.strip(punctuation))
Output:
958-5-Canada
# 用 Python 中的正斜杠上拆分字符串
s = 'canada/japan/australia'
l = s.split('/')
print(l)
Output:
['canada', 'japan', 'australia']
# 根据 Python 中的索引位置将字符串大写
def capitalize(s, ind):
split_s = list(s)
for i in ind:
try:
split_s[i] = split_s[i].upper()
except IndexError:
print('Index out of range : ', i)
return "".join(split_s)
print(capitalize("abracadabra", [2, 6, 9, 10, 50]))
Output:
Index out of range : 50
abRacaDabRA
# 检查字符串中的所有字符是否都是Python中的数字
a = "1000"
x = a.isdigit()
print(x)
b = "A1000"
x = b.isdigit()
print(x)
Output:
True
False
# 为什么使用'=='或'is'比较字符串有时会产生不同的结果
a = 'canada'
b = ''.join(['ca', 'na', 'da'])
print(a == b)
print(a is b)
a = [1, 2, 3]
b = [1, 2, 3]
print(a == b)
print(a is b)
c = b
print(c is b)
Output:
True
False
True
False
True
# 如何在 Python 中为字符串添加 X 个空格
print('canada'.ljust(10) + 'india'.ljust(20) + 'japan')
Output:
canada india japan
# 如何在Python中替换字符串中的特定字符串实例
def nth_replace(str,search,repl,index):
split = str.split(search,index+1)
if len(split)<=index+1:
return str
return search.join(split[:-1])+repl+split[-1]
str1 = "caars caars caars"
str2 = nth_replace(str1, 'aa', 'a', 1)
print(str2)
Output:
caars cars caars
# 如何连接两个变量，一个是字符串，另一个是 Python 中的 int
int1 = 10
str1 = 'test'
print(str(int1) + str1)
Output:
10test
# 在 Python 中的反斜杠上拆分字符串
s = r'canada\japan\australia'
l = s.split('\\')
print(l)
Output:
['canada', 'japan', 'australia']
# 在Python中随机大写字符串中的字母
from random import choice
x = "canada japan australia"
print(''.join(choice((str.upper, str.lower))(c) for c in x))
Output:
CANaDA JaPan auStRALIa
# 在单词处拆分字符串并且或不保留分隔符
import re
string = "Canada AND Japan NOT Audi OR BMW"
l = re.split(r'(AND|OR|NOT)', string)
print(l)
Output:
['Canada ', 'AND', ' Japan ', 'NOT', ' Audi ', 'OR', ' BMW']
# 在 Python 中填充 n 个字符
def header(txt: str, width=30, filler='*', align='c'):
assert align in 'lcr'
return {'l': txt.ljust, 'c': txt.center, 'r': txt.rjust}[align](width, filler)
print(header("Canada"))
print(header("Canada", align='l'))
print(header("Canada", align='r'))
Output:
************Canada************
Canada************************
************************Canada
# 检查变量是否等于一个字符串或另一个字符串
x = 'canada'
if x in ['canada', 'japan', 'germany', 'australia']:
print("Yes")
Output:
true
# Python字符串格式化固定宽度
num1 = 0.04154721841
num2 = 10.04154721841
num3 = 1002.04154721841
print "{0:<12.11g}".format(num1)[:12]
print "{0:<12.11g}".format(num2)[:12]
print "{0:<12.11g}".format(num3)[:12]
Output:
100.041549
0.04159874
12.8878877
# 在Python中查找字符串中字符的所有位置
test = 'canada#japan#uae'
c = '#'
print([pos for pos, char in enumerate(test) if char == c])
Output:
[6, 12]
# 在Python中从左右修剪指定数量的空格
def trim(text, num_of_leading, num_of_trailing):
text = list(text)
for i in range(num_of_leading):
if text[i] == " ":
text[i] = ""
else:
break
for i in range(1, num_of_trailing+1):
if text[-i] == " ":
text[-i] = ""
else:
break
return ''.join(text)
txt1 = " Candada "
print(trim(txt1, 1, 1))
print(trim(txt1, 2, 3))
print(trim(txt1, 6, 8))
Output:
Candada
Candada
Candada
# 在Python中按字符串中字符的位置拆分字符串
str = 'canadajapan'
splitat = 6
l, r = str[:splitat], str[splitat:]
print(l)
print(r)
Output:
canada
japan
# 将Python字符串中的第一个和最后一个字母大写
string = "canada"
result = string[0:1].upper() + string[1:-1].lower() + string[-1:].upper()
print(result)
Output:
CanadA
# 检查字符串是否以Python中的给定字符串或字符结尾
txt = "Canada is a great country"
x = txt.endswith("country")
print(x)
Output:
True
# 如何在 Python 中比较两个字符串
str1 = "Canada"
str2 = "Canada"
print(str1 is str2) # True
print(str1 == str2) # True
string1 = ''.join(['Ca', 'na', 'da'])
string2 = ''.join(['Can', 'ada'])
print(string1 is string2) # False
print(string1 == string2) # True
Output:
True
True
False
True
# 在Python中将整数格式化为带有前导零的字符串
x = 4
x = str(x).zfill(5)
print(x)
Output:
# 在Python中替换字符串的多个子字符串
s = "The quick brown fox jumps over the lazy dog"
for r in (("brown", "red"), ("lazy", "quick")):
s = s.replace(*r)
print(s)
Output:
The quick red fox jumps over the quick dog
# Python字符串替换字符
s = "The quick brown fox jumps over the lazy dog"
for r in (("brown", "red"), ("lazy", "quick")):
s = s.replace(*r)
print(s)
Output:
The quick red fox jumps over the quick dog
# 在Python中查找字符串中所有出现的单词的所有索引
import re
sentence = 'this is a sentence this this'
word = 'this'
for match in re.finditer(word, sentence):
print(match.start(), match.end())
Output:
# 在 Python 中将字符串中每个单词的首字母大写
import string
x = "they're bill's friends from the UK"
x = string.capwords(x)
print(x)
x = x.title()
print(x)
Output:
They're Bill's Friends From The Uk
They'Re Bill'S Friends From The Uk
# 仅在 Python 中的双引号后拆分字符串
s = '"Canada", "Japan", "Germany", "Russia"'
l = ['"{}"'.format(s) for s in s.split('"') if s not in ('', ', ')]
for item in l:
print(item)
Output:
"Canada"
"Japan"
"Germany"
"Russia"
# 在 Python 中以字节为单位获取字符串的大小
string1 = "Canada"
print(len(string1.encode('utf-16')))
Output:
# 在 Python 中比较字符串中的字符
myString = 'AAABBB'
for idx, char in enumerate(myString, ):
if idx + 1 == len(myString):
break
if char == myString[idx + 1]:
print(idx, char, myString[idx + 1])
Output:
0 A A
1 A A
3 B B
4 B B
# 在 Python 中的括号和字符串之间添加空格
import re
test = "example(test)"
test2 = "example(test)example"
test3 = "(test)example"
test4 = "example (test) example"
for i in [test, test2, test3, test4]:
print(re.sub(r"[^\S]?(\(.*?\))[^\S]?", r" \1 ", i).strip())
Output:
example (test)
example (test) example
(test) example
example (test) example
# 在 Python 中删除开头和结尾空格
s = ' canada '
print(s.strip())
Output:
canada
# 在 Python 中拆分字符串以获得第一个值
s = 'canada-japan-australia'
l = s.split('-')[0]
print(l)
string = 'canada-japan-australia'
print(string[:string.index('-')])
Output:
canada
canada
# 在 Python 中检查字符串是大写、小写还是混合大小写
words = ['The', 'quick', 'BROWN', 'Fox',
'jumped', 'OVER', 'the', 'Lazy', 'DOG']
print([word for word in words if word.islower()])
print([word for word in words if word.isupper()])
print([word for word in words if not word.islower() and not word.isupper()])
Output:
['quick', 'jumped', 'the']
['BROWN', 'OVER', 'DOG']
['The', 'Fox', 'Lazy']
# Python计数字符串出现在给定字符串中
txt = "I love Canada, Canada is one of the most impressive countries in the world. Canada is a great country."
x = txt.count("Canada")
print(x)
Output:
# 在 Python3 中用前导零填充字符串
hour = 4
minute = 3
print("{:0>2}:{:0>2}".format(hour, minute))
print("{:0>3}:{:0>5}".format(hour, minute))
print("{:0<3}:{:0<5}".format(hour, minute))
print("{:lt;3}:{:#<5}".format(hour, minute))
Output:
04:03
004:00003
400:30000
4$:3####
# 在 Python 中检查两个字符串是否包含相同的字母和数字
from string import ascii_letters, digits
def compare_alphanumeric(first, second):
for character in first:
if character in ascii_letters + digits and character not in second:
return False
return True
str1 = 'ABCD'
str2 = 'ACDB'
print(compare_alphanumeric(str1, str2))
str1 = 'A45BCD'
str2 = 'ACD59894B'
print(compare_alphanumeric(str1, str2))
str1 = 'A45BCD'
str2 = 'XYZ9887'
print(compare_alphanumeric(str1, str2))
Output:
True
True
False
# 在Python中的字符串中的字符之间添加空格的有效方法
s = "CANADA"
print(" ".join(s))
print("-".join(s))
print(s.replace("", " ")[1: -1])
Output:
C A N A D A
C-A-N-A-D-A
C A N A D A
# 在Python中查找字符串中最后一次出现的子字符串的索引
s = 'What is Canada famous for?'
print(s.find('f'))
print(s.index('f'))
print(s.rindex('f'))
print(s.rfind('f'))
Output:
# 在 Python 中将字符串大写
x = 'canada'
x = x.capitalize()
print(x)
Output:
Canada
# 拆分非字母数字并在 Python 中保留分隔符
import re
s = "65&Can-Jap#Ind^UK"
l = re.split('([^a-zA-Z0-9])', s)
print(l)
Output:
['65', '&', 'Can', '-', 'Jap', '#', 'Ind', '^', 'UK']
# 计算Python中字符串中大写和小写字符的数量
string = "asdfHRbySFss"
uppers = [l for l in string if l.isupper()]
print(len(uppers))
lowers = [l for l in string if l.islower()]
print(len(lowers))
Output:
# 在 Python 中将字符串与枚举进行比较
from enum import Enum, auto
class Signal(Enum):
red = auto()
green = auto()
orange = auto()
def equals(self, string):
return self.name == string
brain_detected_colour = "red"
print(Signal.red.equals(brain_detected_colour))
brain_detected_colour = "pink"
print(Signal.red.equals(brain_detected_colour))
Output:
True
False
# Python中的段落格式
import textwrap
hamlet = '''\
Lorum ipsum is the traditional Latin placeholder text, used when a designer needs a chunk of text for dummying up a layout.
Journo Ipsum is like that, only using some of the most common catchphrases, buzzwords, and bon mots of the future-of-news crowd.
Hit reload for a new batch. For entertainment purposes only.'''
wrapper = textwrap.TextWrapper(initial_indent='\t' * 1,
subsequent_indent='\t' * 2,
width=40)
for para in hamlet.splitlines():
print(wrapper.fill(para))
Output:
Lorum ipsum is the traditional Latin
placeholder text, used when a designer
needs a chunk of text for dummying up
a layout.
Journo Ipsum is like that, only using
some of the most common catchphrases,
buzzwords, and bon mots of the future-
of-news crowd.
Hit reload for a new batch. For
entertainment purposes only.
# 从 Python 中的某个索引替换字符
def nth_replace(str,search,repl,index):
split = str.split(search,index+1)
if len(split)<=index+1:
return str
return search.join(split[:-1])+repl+split[-1]
str1 = "caars caars caars"
str2 = nth_replace(str1, 'aa', 'a', 1)
print(str2)
Output:
caars cars caars
# 如何连接 str 和 int 对象
i = 123
a = "foobar"
s = a + str(i)
print(s)
Output:
foobar123
# 仅在 Python 中将字符串拆分为两部分
s = 'canada japan australia'
l = s.split(' ', 1)
print(l)
Output:
['canada', 'japan australia']
# 将大写字符串转换为句子大小写
text = ['CANADA', 'JAPAN']
text = [txt.capitalize() for txt in text]
print(text)
Output:
['Canada', 'Japan']
# 在标点符号上拆分字符串
string = 'a,b,c d!e.f\ncanada\tjapan&germany'
identifiers = '!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~\n\t '
listitems = "".join((' ' if c in identifiers else c for c in string)).split()
for item in listitems:
print(item)
Output:
a
b
c
d
e
f
canada
japan
germany
# 在 Python 中比较字符串
str1 = "Canada"
str2 = "Canada"
print(str1 is str2) # True
print(str1 == str2) # True
string1 = ''.join(['Ca', 'na', 'da'])
string2 = ''.join(['Can', 'ada'])
print(string1 is string2) # False
print(string1 == string2) # True
Output:
True
True
False
True
# 用零填充数字字符串
num = 123
print('{:<08d}'.format(num))
print('{:>08d}'.format(num))
string = '123'
print(string.ljust(8, '0'))
print(string.rjust(8, '0'))
print(string[::-1].zfill(8)[::-1])
Output:
# 找到两个字符串之间的差异位置
def dif(a, b):
return [i for i in range(len(a)) if a[i] != b[i]]
print(dif('stackoverflow', 'stacklavaflow'))
Output:
[5, 6, 7, 8]
# Python填充字符串到固定长度
number = 4
print(f'{number:05d}') # (since Python 3.6), or
print('{:05d}'.format(number)) # or
print('{0:05d}'.format(number))
print('{n:05d}'.format(n=number)) # or (explicit `n` keyword arg. selection)
print(format(number, '05d'))
Output:
# Python中的字符串查找示例
import re
text = 'This is sample text to test if this pythonic '\
'program can serve as an indexing platform for '\
'finding words in a paragraph. It can give '\
'values as to where the word is located with the '\
'different examples as stated'
find_the_word = re.finditer('as', text)
for match in find_the_word:
print('start {}, end {}, search string \'{}\''.
format(match.start(), match.end(), match.group()))
Output:
start 63, end 65, search string 'as'
start 140, end 142, search string 'as'
start 200, end 202, search string 'as'
# 删除字符串中的开头零和结尾零
list_num = ['000231512-n', '1209123100000-n00000',
'alphanumeric0000', '000alphanumeric']
print([item.strip('0') for item in list_num]) # Remove leading + trailing '0'
print([item.lstrip('0') for item in list_num]) # Remove leading '0'
print([item.rstrip('0') for item in list_num]) # Remove trailing '0'
Output:
['231512-n', '1209123100000-n', 'alphanumeric', 'alphanumeric']
['231512-n', '1209123100000-n00000', 'alphanumeric0000', 'alphanumeric']
['000231512-n', '1209123100000-n', 'alphanumeric', '000alphanumeric']
# Python在换行符上拆分
s = 'line 1\nline 2\nline without newline'
l = s.splitlines(True)
print(l)
Output:
['line 1\n', 'line 2\n', 'line without newline']
# 将字符串中的每个第二个字母大写
s = 'canada'
s = "".join([x.upper() if i % 2 != 0 else x for i, x in enumerate(s)])
print(s)
Output:
cAnAdA
# 在 Python 中查找一个月的最后一个营业日或工作日
import calendar
def last_business_day_in_month(year: int, month: int) -> int:
return max(calendar.monthcalendar(year, month)[-1:][0][:5])
print(last_business_day_in_month(2021, 1))
print(last_business_day_in_month(2021, 2))
print(last_business_day_in_month(2021, 3))
print(last_business_day_in_month(2021, 4))
print(last_business_day_in_month(2021, 5))
Output:
# 比较两个字符串中的单个字符
def compare_strings(a, b):
result = True
if len(a) != len(b):
print('string lengths do not match!')
for i, (x, y) in enumerate(zip(a, b)):
if x != y:
print(f'char miss-match {x, y} in element {i}')
result = False
if result:
print('strings match!')
return result
print(compare_strings("canada", "japan"))
Output:
string lengths do not match!
char miss-match ('c', 'j') in element 0
char miss-match ('n', 'p') in element 2
char miss-match ('d', 'n') in element 4
False
# 在 Python 中多次显示字符串
print('canada' * 3)
print(*3 * ('canada',), sep='-')
Output:
canadacanadacanada
canada-canada-canada
# Python从头开始替换字符串
def nth_replace(s, old, new, occurrence):
li = s.rsplit(old, occurrence)
return new.join(li)
str1 = "caars caars caars caars caars"
str2 = nth_replace(str1, 'aa', 'a', 1)
print(str2)
str2 = nth_replace(str1, 'aa', 'a', 2)
print(str2)
str2 = nth_replace(str1, 'aa', 'a', 3)
print(str2)
Output:
caars caars caars caars cars
caars caars caars cars cars
caars caars cars cars cars
# 在 Python 中连接字符串和变量值
year = '2020'
print('test' + str(year))
print('test' + year.__str__())
Output:
test2020
test2020
# 在每个下划线处拆分字符串并在第 N 个位置后停止
s = 'canada_japan_australia_us_uk'
l = s.split('_', 0)
print(l)
l = s.split('_', 1)
print(l)
l = s.split('_', 2)
print(l)
Output:
['canada_japan_australia_us_uk']
['canada', 'japan_australia_us_uk']
['canada', 'japan', 'australia_us_uk']
# Python中列表中第一个单词的首字母大写
text = ['johnny rotten', 'eddie vedder', 'kurt kobain',
'chris cornell', 'micheal phillip jagger']
text = [txt.capitalize() for txt in text]
print(text)
Output:
['Johnny rotten', 'Eddie vedder', 'Kurt kobain', 'Chris cornell', 'Micheal phillip jagger']
# 如何在 Python 字符串中找到第一次出现的子字符串
test = 'Position of a character'
print(test.find('of'))
print(test.find('a'))
Output:
# 不同长度的Python填充字符串
data = [1148, 39, 365, 6, 56524]
for element in data:
print("{:>5}".format(element))
Output:
# Python比较两个字符串保留一端的差异
def after(s1, s2):
index = s1.find(s2)
if index != -1 and index + len(s2) < len(s1):
return s1[index + len(s2):]
else:
return None
s1 = "canada"
s2 = "can"
print(after(s1, s2))
Output:
ada
# 如何用Python中的一个字符替换字符串中的所有字符
test = 'canada'
print('#39; * len(test))
Output:
$$$
# 在字符串中查找子字符串并在 Python 中返回子字符串的索引
def find_str(s, char):
index = 0
if char in s:
c = char[0]
for ch in s:
if ch == c:
if s[index:index + len(char)] == char:
return index
index += 1
return -1
print(find_str("India Canada Japan", "Canada"))
print(find_str("India Canada Japan", "cana"))
print(find_str("India Canada Japan", "Uae"))
Output:
6
-1
-1
# 从 Python 中的字符串中修剪特定的开头和结尾字符
number = '+91 874854778'
print(number.strip('+'))
print(number.lstrip('+91'))
Output:
# 在 Python 中按长度将字符串拆分为字符串
string = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
x = 3
res = [string[y - x:y] for y in range(x, len(string) + x, x)]
print(res)
Output:
['ABC', 'DEF', 'GHI', 'JKL', 'MNO', 'PQR', 'STU', 'VWX', 'YZ']
# 如何在 Python 中将字符串的第三个字母大写
s = "xxxyyyzzz"
# convert to list
a = list(s)
# change every third letter in place with a list comprehension
a[2::3] = [x.upper() for x in a[2::3]]
# back to a string
s = ''.join(a)
print(s)
Output:
xxXyyYzzZ
# 将制表符大小设置为指定的空格数
txt = "Canada\tis\ta\tgreat\tcountry"
print(txt)
print(txt.expandtabs())
print(txt.expandtabs(2))
print(txt.expandtabs(4))
print(txt.expandtabs(10))
Output:
Canada is a great country
Canada is a great country
Canada is a great country
Canada is a great country
Canada is a great country
# 将两个字符串与某些字符进行比较
str1 = "Can"
str2 = "Canada"
print(str1 in str2)
print(str1.startswith(str2))
print(str2.startswith(str1))
print(str1.endswith(str2))
str3 = "CAN"
print(str3 in str2)
Output:
True
False
True
False
False
# 字符串格式化填充负数
n = [-2, -8, 1, -10, 40]
num = ["{1:0{0}d}".format(2 if x >= 0 else 3, x) for x in n]
print(num)
Output:
n = [-2, -8, 1, -10, 40]
num = ["{1:0{0}d}".format(2 if x >= 0 else 3, x) for x in n]
print(num)
# 单独替换字符串中的第一个字符
str1 = "caars caars caars"
str2 = str1.replace('aa', 'a', 1)
print(str2)
Output:
cars caars caars
# 连接固定字符串和变量
variable = 'Hello'
print('This is the Test File ' + variable)
variable = '10'
print('This is the Test File ' + str(variable))
Output:
This is the Test File Hello
This is the Test File 10
# 将字符串拆分为多个字符串
s = 'str1, str2, str3, str4'
l = s.split(', ')
print(l)
Output:
['str1', 'str2', 'str3', 'str4']
# 在 Python 中将字符串大写
x = "canada japan australia"
x = x[:1].upper() + x[1:]
print(x)
x= x.capitalize()
print(x)
x= x.title()
print(x)
Output:
Canada japan australia
Canada japan australia
Canada Japan Australia
# 将字节字符串拆分为单独的字节
data = b'\x00\x00\x00\x00\x00\x00'
info = [data[i:i + 2] for i in range(0, len(data), 2)]
print(info)
Output:
[b'\x00\x00', b'\x00\x00', b'\x00\x00']
# 用空格填写 Python 字符串
string = 'Hi'.ljust(10)
print(string)
string = 'Hi'.rjust(10)
print(string)
string = '{0: ^20}'.format('Hi')
print(string)
string = '{message: >16}'.format(message='Hi')
print(string)
string = '{message: <16}'.format(message='Hi')
print(string)
string = '{message: <{width}}'.format(message='Hi', width=20)
print(string)
Output:
Hi
Hi
Hi
Hi
Hi
Hi
# 比较两个字符串并检查它们共有多少个字符
from collections import Counter
def shared_chars(s1, s2):
return sum((Counter(s1) & Counter(s2)).values())
print(shared_chars('car', 'carts'))
Output:
# 在 Python 中的数字和字符串之间添加空格
import re
s = "ABC24.00XYZ58.28PQR"
s = re.sub("[A-Za-z]+", lambda group: " " + group[0] + " ", s)
print(s.strip())
Output:
ABC 24.00 XYZ 58.28 PQR
# 如何在 Python 中去除空格
s = ' canada '
print(s.rstrip()) # For whitespace on the right side use rstrip.
print(s.lstrip()) # For whitespace on the left side lstrip.
print(s.strip()) # For whitespace from both side.
s = ' \t canada '
print(s.strip('\t')) # This will strip any space, \t, \n, or \r characters from the left-hand side, right-hand side, or both sides of the string.
Output:
canada
canada
canada
canada
# 字符串中最后一次出现的分隔符处拆分字符串
s = 'canada-japan-australia-uae-india'
l = s.rsplit('-', 1)[1]
print(l)
Output:
india
# 在Python中将字符串的最后一个字母大写
string = "canada"
result = string[:-1] + string[-1].upper()
print(result)
result = string[::-1].title()[::-1]
print(result)
Output:
canadA
canadA
# 使用指定字符居中对齐字符串
txt = "canada"
x = txt.center(20)
print(x)
Output:
canada
# 格式字符串中动态计算的零填充
x = 4
w = 5
print('{number:0{width}d}'.format(width=w, number=x))
Output:
# 在 Python 中使用 string.replace()
a = "This is the island of istanbul"
print (a.replace("is" , "was", 1))
print (a.replace("is" , "was", 2))
print (a.replace("is" , "was"))
Output:
Thwas is the island of istanbul
Thwas was the island of istanbul
Thwas was the wasland of wastanbul
# 在 Python 中获取字符的位置
test = 'Position of a character'
print(test.find('of'))
print(test.find('a'))
Output:
# Python字符串替换多次出现
s = "The quick brown fox jumps over the lazy dog"
for r in (("brown", "red"), ("lazy", "quick")):
s = s.replace(*r)
print(s)
Output:
The quick red fox jumps over the quick dog
# 在索引后找到第一次出现的字符
string = 'This + is + a + string'
x = string.find('+', 4)
print(x)
x = string.find('+', 10)
print(x)
Output:
# 在 Python 中将字符串更改为大写
x = 'canada'
x = x.upper()
print(x)
Output:
CANADA
# 在 Python 中拆分具有多个分隔符的字符串
import re
l = re.split(r'[$-]+', 'canada$-india$-japan$-uae')
print(l)
Output:
['canada', 'india', 'japan', 'uae']
# 在 Python 中获取字符串的大小
string1 = "Canada"
print(len(string1))
string2 = " Canada"
print(len(string2))
string3 = "Canada "
print(len(string3))
Output:
# Python中的字符串比较 is vs ==
x = 'canada'
y = ''.join(['ca', 'na', 'da'])
print(x == y)
print(x is y)
x = [1, 2, 3]
y = [1, 2, 3]
print(x == y)
print(x is y)
z = y
print(z is y)
Output:
True
False
True
False
True
# 每当数字与非数字相邻时，Python 正则表达式都会添加空格
import re
text = ['123', 'abc', '4x5x6', '7.2volt', '60BTU',
'20v', '4*5', '24in', 'google.com-1.2', '1.2.3']
pattern = r'(-?[0-9]+\.?[0-9]*)'
for data in text:
print(repr(data), repr(
' '.join(segment for segment in re.split(pattern, data) if segment)))
Output:
'123' '123'
'abc' 'abc'
'4x5x6' '4 x 5 x 6'
'7.2volt' '7.2 volt'
'60BTU' '60 BTU'
'20v' '20 v'
'4*5' '4 * 5'
'24in' '24 in'
'google.com-1.2' 'google.com -1.2'
'1.2.3' '1.2 . 3'
# 在 Python 中仅按第一个空格拆分字符串
s = 'canada japan australia'
l = s.split(' ', 1)
print(l)
Output:
['canada', 'japan australia']
# 在Python中将字符串中的一些小写字母更改为大写
indices = set([0, 7, 14, 18])
s = "i love canada and japan"
print("".join(c.upper() if i in indices else c for i, c in enumerate(s)))
Output:
I love Canada And Japan
# 将字符串拆分为具有多个单词边界分隔符的单词
import re
thestring = "a,b,c d!e.f\ncanada\tjapan&germany"
listitems = re.findall('\w+', thestring)
for item in listitems:
print(item)
Output:
a
b
c
d
e
f
canada
japan
germany
# 检查一个字符串在 Python 中是否具有相同的字符
str1 = 'caars'
str2 = 'rats'
str3 = 'racs'
print(set(str1)==set(str2))
print(set(str1)==set(str3))
Output:
False
True
# 在多个分隔符或指定字符上拆分字符串
import re
string_test = "Ethnic (279), Responses (3), 2016 Census - 25% Sample"
print(re.findall(r"[\w']+", string_test))
def split_by_char(s, seps):
res = [s]
for sep in seps:
s, res = res, []
for seq in s:
res += seq.split(sep)
return res
print(split_by_char(string_test, [' ', '(', ')', ',']))
Output:
['Ethnic', '279', 'Responses', '3', '2016', 'Census', '25', 'Sample']
['Ethnic', '', '279', '', '', 'Responses', '', '3', '', '', '2016', 'Census', '-', '25%', 'Sample']
# 将一个字符串附加到另一个字符串
# Example 1
str1 = "Can"
str2 = "ada"
str3 = str1 + str2
print(str3)
# Example 2
str4 = 'Ca'
str4 += 'na'
str4 += 'da'
print(str4)
# Example 3
join_str = "".join((str1, str2))
print(join_str)
# Example 4
str_add = str1.__add__(str2)
print(str_add)
Output:
Canada
Canada
Canada
Canada
# 在 Python 中遍历字符串
# Example 1
test_str = "Canada"
for i, c in enumerate(test_str):
print(i, c)
print("------------------------")
# Example 2
indx = 0
while indx < len(test_str):
print(indx, test_str[indx])
indx += 1
print("------------------------")
# Example 3
for char in test_str:
print(char)
Output:
0 C
1 a
2 n
.......
d
a
# 从 Python 中的字符串中去除标点符号
import string
import re
# Example 1
s = "Ethnic (279), Responses (3), 2016 Census - 25% Sample"
out = re.sub(r'[^\w\s]', '', s)
print(out)
# Example 2
s = "Ethnic (279), Responses (3), 2016 Census - 25% Sample"
for p in string.punctuation:
s = s.replace(p, "")
print(s)
# Example 3
s = "Ethnic (279), Responses (3), 2016 Census - 25% Sample"
out = re.sub('[%s]' % re.escape(string.punctuation), '', s)
print(out)
Output:
Ethnic 279 Responses 3 2016 Census 25 Sample
Ethnic 279 Responses 3 2016 Census 25 Sample
Ethnic 279 Responses 3 2016 Census 25 Sample
# 将列表转换为字符串
list_exp = ['Ca', 'na', 'da']
print(type(list_exp))
# Example 1
str_exp1 = ''.join(list_exp)
print(type(str_exp1))
print(str_exp1)
# Example 2
str_exp2 = ''.join(str(e) for e in list_exp)
print(type(str_exp2))
print(str_exp2)
# Example 3
str_exp3 = ''.join(map(str, list_exp))
print(type(str_exp2))
print(str_exp2)
Output:
class 'list'
class 'str'
Canada
class 'str'
Canada
class 'str'
Canada
# 将 JSON 转换为字符串
import json
# list with dict a simple Json format
json_exp = \
[{"id": "12", "name": "Mark"}, {"id": "13", "name": "Rock", "date": None}]
print(type(json_exp))
str_conv = json.dumps(json_exp) # string
print(type(str_conv))
print(str_conv)
Output:
class 'list'
class 'str'
[{"id": "12", "name": "Mark"}, {"id": "13", "name": "Rock", "date": null}]
# 对字符串列表进行排序
# Example 1
str_list = ["Japan", "Canada", "Australia"]
print(str_list)
str_list.sort()
print(str_list)
# Example 2
str_list = ["Japan", "Canada", "Australia"]
for x in sorted(str_list):
print(x)
# Example 3
str_var = "Canada"
strlist = sorted(str_var)
print(strlist)
Output:
['Japan', 'Canada', 'Australia']
['Australia', 'Canada', 'Japan']
Australia
Canada
Japan
['C', 'a', 'a', 'a', 'd', 'n']
# 在 Python 中检查字符串是否以 XXXX 开头
import re
exp_str = "Python Programming"
# Example 1
if re.match(r'^Python', exp_str):
print(True)
else:
print(False)
# Example 2
result = exp_str.startswith("Python")
print(result)
Output:
True
True
# 在 Python 中将两个字符串网格或交错在一起的不同方法
str1 = "AAAA"
str2 = "BBBBBBBBB"
# Example 1
mesh = "".join(i + j for i, j in zip(str1, str2))
print("Example 1:", mesh)
# Example 2
min_len = min(len(str1), len(str2))
mesh = [''] * min_len * 2
mesh[::2] = str1[:min_len]
mesh[1::2] = str2[:min_len]
print("Example 2:", ''.join(mesh))
# Example 3
mesh = ''.join(''.join(item) for item in zip(str1, str2))
print("Example 3:", mesh)
# Example 4
min_len = min(len(str1), len(str2))
mesh = [''] * min_len * 2
mesh[::2] = str1[:min_len]
mesh[1::2] = str2[:min_len]
mesh += str1[min_len:] + str2[min_len:]
print("Example 4:", ''.join(mesh))
Output:
Example 1: ABABABAB
Example 2: ABABABAB
Example 3: ABABABAB
Example 4: ABABABABBBBBB
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