Python-在数据框中查找具有相同ID的元素并将其分组 [英] Python - Find elements with same id in a dataframe and group together

问题描述

我有一个像这样的数据框:

I have a data-frame like this :

id  value1 value2
 0     1     1
 1     2     3
 2     1     4
 3     1     5
 4     2     1

我希望它是这样的:

id  value1 value2  count
 0     1     1,4,5   3
 1     2     3,1     2

推荐答案

通过

Use aggregation by agg with join and size, but is necessary converting column to strings:

tups = [('value2', lambda x: ','.join(x.astype(str))), ('count', 'size')]
df1 = df.groupby('value1')['value2'].agg(tups).reset_index()
print (df1)
   value1 value2  count
0       1  1,4,5      3
1       2    3,1      2

替代:

tups = [('value2', ','.join), ('count', 'size')]
df1 = df['value2'].astype(str).groupby(df['value1']).agg(tups).reset_index()

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