Series.str.endswith(pat, na=nan)

Test if the end of each string element matches a pattern.

>>> s = pd.Series(['bat', 'bear', 'caT', np.nan])
>>> s.str.endswith('t') 
0     True 
1    False 
2    False 
3      NaN

>>> s.str.endswith('t', na=False)
0     True
1    False
2    False
3    False

Series.str.split(pat=None, n=-1, expand=False)

Split strings around given separator/delimiter.

>>> s = pd.Series(["this is a regular sentence",
"https://docs.python.org/3/tutorial/index.html", np.nan])

可指定某字串做切割，例如用“/"切網址，或用“@"切Email

>>> s.str.split(pat = "/")
0                         [this is a regular sentence]
1    [https:, , docs.python.org, 3, tutorial, index...
2                                                  NaN

也可以指定切的字串數量和方向

>>> s.str.split(n=2)
0                     [this, is, a regular sentence]
1    [https://docs.python.org/3/tutorial/index.html]
2                                                NaN
dtype: object

>>> s.str.rsplit(n=2)
0                     [this is a, regular, sentence]
1    [https://docs.python.org/3/tutorial/index.html]
2                                                NaN

Counter()

>>> from collections import Counter
>>> z = ['blue', 'red', 'blue', 'yellow', 'blue', 'red']
>>> Counter(z)
Counter({'blue': 3, 'red': 2, 'yellow': 1})

words = ['a', 'b', 'c', 'a']

Counter(words).keys() # equals to list(set(words))
Counter(words).values()# counts the elements' frequency

可分別列出 list(set(words)) 和 elements’ frequency
Output:

['a', 'c', 'b']
[2, 1, 1]

也可以frequency最高的:

>>> from collections import Counter
>>> A = {'a' : 1, 'b' : 3, 'c' : 2, 'd' : 4, 'e' : 0, 'f' :5}
>>> dict(Counter(A).most_common(5))
{'a': 1, 'c': 2, 'b': 3, 'd': 4, 'f': 5}

pandas.Series.str.endswith

pandas.Series.str.split