pandas 的大小和数量有什么区别? [英] What is the difference between size and count in pandas?

问题描述

这是熊猫中groupby("x").count和groupby("x").size之间的区别吗?

That is the difference between groupby("x").count and groupby("x").size in pandas ?

大小是否只排除nil?

Does size just exclude nil ?

推荐答案

count 不会:

size includes NaN values, count does not:

In [46]:
df = pd.DataFrame({'a':[0,0,1,2,2,2], 'b':[1,2,3,4,np.NaN,4], 'c':np.random.randn(6)})
df

Out[46]:
   a   b         c
0  0   1  1.067627
1  0   2  0.554691
2  1   3  0.458084
3  2   4  0.426635
4  2 NaN -2.238091
5  2   4  1.256943

In [48]:
print(df.groupby(['a'])['b'].count())
print(df.groupby(['a'])['b'].size())

a
0    2
1    1
2    2
Name: b, dtype: int64

a
0    2
1    1
2    3
dtype: int64 

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