小白的Python學習筆記（十七）數據挖掘經常使用包- Pandas（6）

有關字符串基本方法

你們好，我又回來了！ 以前的幾期咱們簡單瞭解了pandas的基礎操做，可是隻要涉及到數據，最多見的就是String（字符串）類型，所以不少時候咱們其實都在和字符串打交道，因此今天，我會把有關字符串的經常使用方法分享，但願可以幫到各位小夥伴~

Split and format

latitude = '37.24N'
longitude = '-115.81W'
'Coordinates {0},{1}'.format(latitude,longitude)
>>>   'Coordinates 37.24N,-115.81W'
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f'Coordinates {latitude},{longitude}'
>>>'Coordinates 37.24N,-115.81W'
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'{0},{1},{2}'.format(*('abc'))
>>>'a,b,c'
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coord = {"latitude":latitude,"longitude":longitude}
'Coordinates {latitude},{longitude}'.format(**coord)
>>>'Coordinates 37.24N,-115.81W'
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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})'
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test_point = Point(4,2)
test_point
>>>    Point(4,2)
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str(Point(4,2))
>>>'Point(4,2)'
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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 "

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Align :

'{:<30}'.format('left aligned')
>>>'left aligned '
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'{:>30}'.format('right aligned')
>>>' right aligned'
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'{:^30}'.format('centerd')
>>>' centerd '
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'{:*^30}'.format('centerd')
>>>'***********centerd************'
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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'
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'{:,}'.format(12345677)
>>>'12,345,677'
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Percentage :

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

import datetime as dt
f"{dt.datetime.now():%Y-%m-%d}"
>>>'2019-03-27'
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f"{dt.datetime.now():%d_%m_%Y}"
>>>'27_03_2019'
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today = dt.datetime.today().strftime("%d_%m_%Y")
today
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'27_03_2019'
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Split without parameters :

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

'do'*2
>>>'dodo'
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orig_string ='Hello'
orig_string+',World'
>>>'Hello,World'
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full_sentence = orig_string+',World'
full_sentence
>>>'Hello,World'
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Check string type , slice，count，strip :

strings = ['do','re','mi']
', '.join(strings)
>>>'do, re, mi'
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'z' not in 'abc'
>>> True
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ord('a'), ord('#')
>>> (97, 35)
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chr(97)
>>>'a'
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s = "foodbar"
s[2:5]
>>>'odb'
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s[:4] + s[4:]
>>>'foodbar'
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s[:4] + s[4:] == s
>>>True
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t=s[:]
id(s)
>>>1547542895336
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id(t)
>>>1547542895336
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s is t
>>>True
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s[0:6:2]
>>>'fob'
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s[5:0:-2]
>>>'ado'
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s = 'tomorrow is monday'
reverse_s = s[::-1]
reverse_s
>>>'yadnom si worromot'
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s.capitalize()
>>>'Tomorrow is monday'
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s.upper()
>>>'TOMORROW IS MONDAY'
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s.title()
>>>'Tomorrow Is Monday'
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s.count('o')
>>> 4
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"foobar".startswith('foo')
>>>True
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"foobar".endswith('ar')
>>>True
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"foobar".endswith('oob',0,4)
>>>True
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"foobar".endswith('oob',2,4)
>>>False
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"My name is yo, I work at SG".find('yo')
>>>11
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# If can't find the string, return -1
"My name is ya, I work at Gener".find('gent')
>>>-1

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# Check a string if consists of alphanumeric characters
"abc123".isalnum()
>>>True
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"abc%123".isalnum()
>>>False
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"abcABC".isalpha()
>>>True
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"abcABC1".isalpha()
>>>False
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'123'.isdigit()
>>>True
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'123abc'.isdigit()
>>>False
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'abc'.islower()
>>>True
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"This Is A Title".istitle()
>>>True
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"This is a title".istitle()
>>>False
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'ABC'.isupper()
>>>True
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'ABC1%'.isupper()
>>>True
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'foo'.center(10)
>>>' foo '
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' foo bar baz '.strip()
>>>'foo bar baz'
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' foo bar baz '.lstrip()
>>>'foo bar baz '
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' foo bar baz '.rstrip()
>>>' foo bar baz'
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"foo abc foo def fo ljk ".replace('foo','yao')
>>>'yao abc yao def fo ljk '

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'www.realpython.com'.strip('w.moc')
>>>'realpython'
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'www.realpython.com'.strip('w.com')
>>>'realpython'
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'www.realpython.com'.strip('w.ncom')
>>>'realpyth'
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Convert to lists :

', '.join(['foo','bar','baz','qux'])
>>>'foo, bar, baz, qux'
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list('corge')
>>>['c', 'o', 'r', 'g', 'e']
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':'.join('corge')
>>>'c:o:r:g:e'
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'www.foo'.partition('.')
>>>('www', '.', 'foo')
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'foo@@bar@@baz'.partition('@@')
>>>('foo', '@@', 'bar@@baz')
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'foo@@bar@@baz'.rpartition('@@')
>>>('foo@@bar', '@@', 'baz')
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'foo.bar'.partition('@@')
>>>('foo.bar', '', '')
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# By default , rsplit split a string with white space
'foo bar adf yao'.rsplit()
>>>['foo', 'bar', 'adf', 'yao']
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'foo.bar.adf.ert'.split('.')
>>>['foo', 'bar', 'adf', 'ert']
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'foo\nbar\nadfa\nlko'.splitlines()
>>>['foo', 'bar', 'adfa', 'lko']
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總結

除了我以上總結的這些，還有太多很是實用的方法，你們能夠根據本身的需求去搜索啦！

我把這一期的ipynb文件和py文件放到了Github上，你們若是想要下載能夠點擊下面的連接：

• Github倉庫地址： github.com/yaozeliang/…