Pandas之旅（六): 字串實用方法彙總

Pandas · 發表 2019-03-28 04:00:52

摘要：有關字串基本方法大家好，我又回來了！之前的幾期我們已經簡單瞭解了pandas的基礎操作，但是隻要涉及到資料，最常見的就是String（字串）型別，所以很多時候我們其實都在和字串打交道，所以今天，我會把我自己總結的，有關字串的常用方法分享給大家，希望能夠幫到各位小夥伴~ Split ...

有關字串基本方法

大家好，我又回來了！之前的幾期我們已經簡單瞭解了pandas的基礎操作，但是隻要涉及到資料，最常見的就是String（字串）型別，所以很多時候我們其實都在和字串打交道，所以今天，我會把我自己總結的，有關字串的常用方法分享給大家，希望能夠幫到各位小夥伴~

Split and format

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

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 atest".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 foljk ".replace('foo','yao')
>>>'yao abc yao def foljk '

'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']

總結

除了我以上總結的這些，還有太多非常實用的方法，大家可以根據自己的需求去搜索啦！

我把這一期的ipynb檔案和py檔案放到了Github上，大家如果想要下載可以點選下面的連結：

Github倉庫地址：https://github.com/yaozeliang/pandas_share

希望大家能夠繼續支援我，完結，撒花