Python RegEx

RegEx ko kuma sabonin na bayyana girmuwarin na nazarin

RegEx za iya yin girmuwarin da na cikin string a cikin sabonin da an zartar

Modulu RegEx

Python yana mutumma ne re 的内置包，可用于处理正则表达式。

导入 re 模块：

import re

Python 中的 RegEx

导入 re 模块后，就可以开始使用正则表达式了：

Misali

检索字符串以查看它是否以 "China" 开头并以 "country" 结尾：

import re
txt = "China is a great country"
x = re.search("^China.*country$", txt)

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RegEx 函数

re 模块提供了一组函数，允许我们检索字符串以进行匹配：

函数 ba da
findall 返回包含所有匹配项的列表
search 如果字符串中的任意位置存在匹配，则返回 Match 对象
split 返回在每次匹配时拆分字符串的列表
sub 用字符串替换一个或多个匹配项

元字符

元字符是具有特殊含义的字符：

字符 ba da 示例 TIY
[] 一组字符 "[a-m]" ci gaba
\ 示意特殊序列（也可用于转义特殊字符） "\d" ci gaba
. 任何字符（换行符除外） "he..o" ci gaba
^ 起始于 "^hello" ci gaba
$ 结束于 "world$" ci gaba
* 零次或多次出现 "aix*" ci gaba
+ 一次或多次出现 "aix+" ci gaba
{} 确切地指定的出现次数 "al{2}" ci gaba
| 两者任一 "falls|stays" ci gaba
()` 捕获和分组

特殊序列

特殊序列指的是 \ 后跟下表中的某个字符，拥有特殊含义：

字符 ba da 示例 TIY
\A 如果指定的字符位于字符串的开头，则返回匹配项 "\AThe" ci gaba
\b 返回指定字符位于单词的开头或末尾的匹配项 r"\bain"
r"ain\b" 		ci gaba
ci gaba
\B 返回指定字符存在的匹配项，但不在单词的开头（或结尾处） r"\Bain"
r"ain\B" 		ci gaba
ci gaba
\d 返回字符串包含数字的匹配项（数字 0-9） "\d" ci gaba
\D 返回字符串不包含数字的匹配项 "\D" ci gaba
\s 返回字符串包含空白字符的匹配项 "\s" ci gaba
\S 返回字符串不包含空白字符的匹配项 "\S" ci gaba
\w 返回一个匹配项，其中字符串包含任何单词字符
（从 a 到 Z 的字符，从 0 到 9 的数字和下划线 _ 字符）		 "\w" ci gaba
\W 返回一个匹配项，其中字符串不包含任何单词字符 "\W" ci gaba
\Z 如果指定的字符位于字符串的末尾，则返回匹配项 "Spain\Z" ci gaba

集合（Set）

ciki (Set) ita ce kiyace-kiyace a ciki, wanda ke da kiyace-kiyace a ciki [] a ciki na ciki, wanda ke da mahimmanci da yawa:

ciki ba da ci gaba
[arn] a ciki na a kaiwa aiki a kaiwa aiki ci gaba
[a-n] a ciki na a kaiwa aiki a kaiwa aiki ci gaba
[^arn] a ciki na a kaiwa aiki a kaiwa aiki ci gaba
[0123] a ciki na a kaiwa aiki a kaiwa aiki ci gaba
[0-9] a ciki na a kaiwa aiki a kaiwa aiki ci gaba
[0-5][0-9] a ciki na a kaiwa aiki a kaiwa aiki ci gaba
[a-zA-Z] a ciki na a kaiwa aiki a kaiwa aiki, kuma a kaiwa aiki a kaiwa aiki ci gaba
[+] a ciki, +, *, ., |, (), $, {} suna da yawa, kuma [+] yana nufin: ci gaba

fannan findall()

findall() fannan kuma ta a gina tsarin a kaiwa aiki a kaiwa aiki

Misali

a ciki na a kaiwa aiki a kaiwa aiki

import re
str = "China is a great country"
x = re.findall("a", str)
print(x)

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a kowane a kaiwa aiki a kaiwa aiki a kaiwa aiki

a kowane a kaiwa aiki a kaiwa aiki

Misali

a kowane a kaiwa aiki a kaiwa aiki

import re
str = "China is a great country"
x = re.findall("USA", str)
print(x)

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fannan search()

search() fannan kuma ta a nazarin a kaiwa aiki a kaiwa aiki, kowane a kaiwa aiki a kaiwa aiki

a kowane a kaiwa aiki a kaiwa aiki

Misali

yana nazarin kanananin dake a kaiwa aiki

import re
str = "China is a great country"
x = re.search("\s", str)
print("The first white-space character is located in position:", x.start())

Run Misali

a kowane a kaiwa aiki a kaiwa aiki None:

Misali

yana nazarin a kaiwa aiki

import re
str = "China is a great country"
x = re.search("USA", str)
print(x)

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fannan split()

split() fannan kuma ta a gina tsarin a kaiwa aiki a kowane aiki

Misali

yana kaiya a kaiwa kanananin dake

import re
str = "China is a great country"
x = re.split("\s", str)
print(x)

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Zai iya kawo amfani da maxsplit amfani da dona a kaiwa aiki

Misali

yana kaiya kafin a kaiwa aiki

import re
str = "China is a great country"
x = re.split("\s", str, 1)
print(x)

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fannan sub()

sub() fannan kuma ta yin aiki na mutum

Misali

da 9 ya a kanananin dake

import re
str = "China is a great country"
x = re.sub("\s", "9", str)
print(x)

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Zai iya kawo amfani da count Paramita don kawo karshen koyin:

Misali

Koyi daga sabon hanyar:

import re
str = "China is a great country"
x = re.sub("\s", "9", str, 2)
print(x)

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Obaje Kwallon Kwallon

Obaje Kwallon Kwallon yana da dukkanin ta'amurin da a samu game da nazarin da a samu:

Iyali:Daga bai kuma a samu, za a cika kashi Nonedaga, ba Match Obaje ba.

Misali

A zama za a samu Obaje Kwallon Kwallon

import re
str = "China is a great country"
x = re.search("a", str)
print(x) # Za a cika da shirin obaje

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Match Obaje ya bayyana dukkanin hanyoyin da za a iya samun ta'amurin da a samu:

  • span() Ciki da takaluma na farko da kusa
  • .string Ciki da kalmomi da a shirya
  • group() Ciki da kalmomi da a samu

Misali

Ciki da kalmomi da a samu a farko (tunawa da kusa).

Tafiyar Kwallon Kwallon da ke haɗa da kiyayya "C" a cikin kalmomi:

import re
str = "China is a great country"
x = re.search(r"\bC\w+", str)
print(x.span())

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Misali

Ciki da kalmomi da a shirya

import re
str = "China is a great country"
x = re.search(r"\bC\w+", str)
print(x.string)

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Misali

Ciki da kalmomi da a samu

Tafiyar Kwallon Kwallon da ke haɗa da kiyayya "C" a cikin kalmomi:

import re
str = "China is a great country"
x = re.search(r"\bC\w+", str)
print(x.group())

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Iyali:Daga bai kuma a samu, za a cika kashi Nonedaga, ba Match Obaje ba.