python 字符串处理

1.In and not in 

---

>>> string = "this is a string".split()

如果字符串包含在字符中则放回真，如果不包含在字符串中则返回假

>>> "a" in string   

True

>>> "b" in string

False

如果字符串不再另外一个字符串中，则返回真，如果在则返回假

>>> "b" not in string

True

2.find and  index

---

>>> string = "this is a string".split()

判断字符串在另外一个字符串中的什么位置

>>> string.split().index("this")

0

>>> string.split().index("is")

1

>>> string.split().index("a")

2

>>> string.split().index("string")

3

3. startswith() 和endswith()

---

>>>string = "this is a string"

>>> string.startswith("this")

True

>>> string.endswith("string")

True

4. lstrip()、retrip()和strip

可以去掉前后的空格，也可以删除前后的任何内容

lstrip() 取出删除前导空白

retrip() 删除结尾空白

strip() 删除前后空白

>>> spacious_string = "\n\t Some Non-Spacious Test\n \t\r"

>>> print spacious_string

  Some Non-Spacious Test

 

>>> spacious_string.lstrip()   

'Some Non-Spacious Test\n \t\r'

>>> spacious_string.rstrip()

'\n\t Some Non-Spacious Test'

>>> spacious_string.strip()

'Some Non-Spacious Test'

>>> xml_tag = "<some_tag>"

>>> xml_tag

'<some_tag>'

>>> xml_tag.lstrip('<')

'some_tag>'

>>> xml_tag.rstrip(">")

'<some_tag'

>>> xml_tag.strip("<>")

'some_tag'

upper() 和 lower()

---

lower  返回的是小写的字符串 

upper 返回的是大写的字符串

>>> mixed_case_string = "VOrpal Bunny"

>>> mixed_case_string == "vorpal bunny"

False

>>> mixed_case_string.lower() == "vorpal bunny"

True

>>> mixed_case_string == "VORPAL BUNNY"

False

>>> mixed_case_string.upper() == "VORPAL BUNNY"

True

>>> mixed_case_string.lower()

'vorpal bunny'

>>> mixed_case_string.upper()

'VORPAL BUNNY'

split()

---

split() 把希望作为分隔符的分隔字符串传递给它，无论是管道符还是其它的都属于字符串

1。下面是以管道符传递给split()，默认的分隔符是逗号或空格。

>>> comma_delim_string = "pos1,pos2,pos3"

>>> comma_delim_string

'pos1,pos2,pos3'

>>> pipe_delim_string = "pipepos1|pipepos2|pipepos3"

>>> comma_delim_string.split()

['pos1,pos2,pos3']

>>> pipe_delim_string.split("|")

['pipepos1', 'pipepos2', 'pipepos3']

2。以字符串字幕或数字作为分隔符，下面的例子是abc也可以是其它 

>>> a = "1abc2abc3"

>>> a.split("abc")

['1', '2', '3']

3. 根据定界符第几次出现的次数进行分割

>>> string_1 = "hello,what are you doing,thanks,i'm fine"

>>> string_1

"hello,what are you doing,thanks,i'm fine"

>>> string_1.split(',',1)

['hello', "what are you doing,thanks,i'm fine"]

>>> string_1.split(',',2)

['hello', 'what are you doing', "thanks,i'm fine"]

>>> string_1.split(',',3)

['hello', 'what are you doing', 'thanks', "i'm fine"]

4。splitlines()  对多行文本按照行的方式进行分割

>>> string_2 = """what's you name

My name is james,

and you

"""

>>> string_2

"what's you name\nMy name is james,\nand you\n"

>>> string_2.split()

["what's", 'you', 'name', 'My', 'name', 'is', 'james,', 'and', 'you']

>>> string_2.splitlines()

["what's you name", 'My name is james,', 'and you']

join()

---

join()函数进行字符串的合并，多个字符串合并到一起

>>> string_3 = ['a','b','c','d']

>>> string_3

['a', 'b', 'c', 'd']

>>>

>>> ','.join(string_3)

'a,b,c,d'

>>> '@'.join(string_3)

'a@b@c@d'

replace()

---

字符串的替换

>>> string_5 = "My name is james"

>>> string_5.replace("james","alex")

'My name is alex'