有关字符串基本方法

大家好，我又回来了！ 之前的几期我们已经简单了解了pandas的基础操作，但是只要涉及到数据，最常见的就是String（字符串）类型，所以很多时候我们其实都在和字符串打交道，所以今天，我会把我自己总结的，有关字符串的常用方法分享给大家，希望能够帮到各位小伙伴~

Split and format

latitude = '37.24N'
longitude = '-115.81W'
'Coordinates {0},{1}'.format(latitude,longitude)
>>>   'Coordinates 37.24N,-115.81W'

f'Coordinates {latitude},{longitude}'
>>>'Coordinates 37.24N,-115.81W'

'{0},{1},{2}'.format(*('abc'))
>>>'a,b,c'

coord = {"latitude":latitude,"longitude":longitude}
'Coordinates {latitude},{longitude}'.format(**coord)
>>>'Coordinates 37.24N,-115.81W'

Access argument' s attribute

class Point:
    def __init__(self,x,y):
        self.x,self.y = x,y
    def __str__(self):
        return 'Point({self.x},{self.y})'.format(self = self)
    def __repr__(self):
        return f'Point({self.x},{self.y})'

test_point = Point(4,2)
test_point
>>>    Point(4,2)

str(Point(4,2))
>>>'Point(4,2)'

Replace with %s , %r :

" repr() shows the quote {!r}, while str() doesn't:{!s} ".format('a1','a2')
>>> " repr() shows the quote 'a1', while str() doesn't:a2 "

Align :

'{:<30}'.format('left aligned')
>>>'left aligned                  '

'{:>30}'.format('right aligned')
>>>'                 right aligned'

'{:^30}'.format('centerd')
>>>'           centerd            '

'{:*^30}'.format('centerd')
>>>'***********centerd************'

Replace with %x , %o :

"int:{0:d}, hex:{0:x}, oct:{0:o}, bin:{0:b}".format(42)
>>>'int:42, hex:2a, oct:52, bin:101010'

'{:,}'.format(12345677)
>>>'12,345,677'

Percentage :

points = 19
total = 22
'Correct answers: {:.2%}'.format(points/total)
>>>'Correct answers: 86.36%'

Date :

import datetime as dt
f"{dt.datetime.now():%Y-%m-%d}"
>>>'2019-03-27'

f"{dt.datetime.now():%d_%m_%Y}"
>>>'27_03_2019'

today = dt.datetime.today().strftime("%d_%m_%Y")
today

'27_03_2019'

Split without parameters :

"this is a  test".split()
>>>['this', 'is', 'a', 'test']

Concatenate :

'do'*2
>>>'dodo'

orig_string ='Hello'
orig_string+',World'
>>>'Hello,World'

full_sentence = orig_string+',World'
full_sentence
>>>'Hello,World'

Check string type , slice，count，strip :

strings = ['do','re','mi']
', '.join(strings)
>>>'do, re, mi'

'z' not in 'abc'
>>> True

ord('a'), ord('#')
>>> (97, 35)

chr(97)
>>>'a'

s = "foodbar"
s[2:5]
>>>'odb'

s[:4] + s[4:]
>>>'foodbar'

s[:4] + s[4:] == s
>>>True

t=s[:]
id(s)
>>>1547542895336

id(t)
>>>1547542895336

s is t
>>>True

s[0:6:2]
>>>'fob'

s[5:0:-2]
>>>'ado'

s = 'tomorrow is monday'
reverse_s = s[::-1]
reverse_s
>>>'yadnom si worromot'

s.capitalize()
>>>'Tomorrow is monday'

s.upper()
>>>'TOMORROW IS MONDAY'

s.title()
>>>'Tomorrow Is Monday'

s.count('o')
>>> 4

"foobar".startswith('foo')
>>>True

"foobar".endswith('ar')
>>>True

"foobar".endswith('oob',0,4)
>>>True

"foobar".endswith('oob',2,4)
>>>False

"My name is yo, I work at SG".find('yo')
>>>11

# If can't find the string, return -1
"My name is ya, I work at Gener".find('gent')
>>>-1

# Check a string if consists of alphanumeric characters
"abc123".isalnum()
>>>True

"abc%123".isalnum()
>>>False

"abcABC".isalpha()
>>>True

"abcABC1".isalpha()
>>>False

'123'.isdigit()
>>>True

'123abc'.isdigit()
>>>False

'abc'.islower()
>>>True

"This Is A Title".istitle()
>>>True

"This is a title".istitle()
>>>False

'ABC'.isupper()
>>>True

'ABC1%'.isupper()
>>>True

'foo'.center(10)
>>>'   foo    '

'   foo bar baz    '.strip()
>>>'foo bar baz'

'   foo bar baz    '.lstrip()
>>>'foo bar baz    '

'   foo bar baz    '.rstrip()
>>>'   foo bar baz'

"foo abc foo def fo  ljk ".replace('foo','yao')
>>>'yao abc yao def fo  ljk '

'www.realpython.com'.strip('w.moc')
>>>'realpython'

'www.realpython.com'.strip('w.com')
>>>'realpython'

'www.realpython.com'.strip('w.ncom')
>>>'realpyth'

Convert to lists :

', '.join(['foo','bar','baz','qux'])
>>>'foo, bar, baz, qux'

list('corge')
>>>['c', 'o', 'r', 'g', 'e']

':'.join('corge')
>>>'c:o:r:g:e'

'www.foo'.partition('.')
>>>('www', '.', 'foo')

'foo@@bar@@baz'.partition('@@')
>>>('foo', '@@', 'bar@@baz')

'foo@@bar@@baz'.rpartition('@@')
>>>('foo@@bar', '@@', 'baz')

'foo.bar'.partition('@@')
>>>('foo.bar', '', '')

# By default , rsplit split a string with white space
'foo bar adf yao'.rsplit()
>>>['foo', 'bar', 'adf', 'yao']

'foo.bar.adf.ert'.split('.')
>>>['foo', 'bar', 'adf', 'ert']

'foo\nbar\nadfa\nlko'.splitlines()
>>>['foo', 'bar', 'adfa', 'lko']

总结

除了我以上总结的这些，还有太多非常实用的方法，大家可以根据自己的需求去搜索啦！

我把这一期的ipynb文件和py文件放到了Github上，大家如果想要下载可以点击下面的链接：

• Github仓库地址： https://github.com/yaozeliang/pandas_share

希望大家能够继续支持我，完结，撒花