比较数据帧并输出计数匹配数 [英] Compare dataframes and output the numbers of count matches

问题描述

我想计算一个数据帧在另一个数据帧中的出现次数，并输出匹配计数.

I would like to count occurences of one dataframe in another dataframe and output the counts of matches.

df
   group1  group2
0  orange  orange
1   apple   apple
2  banana    pear
3  banana  banana

.

fruit_df
   fruits
0  orange
1  banana

所以:

 groups = ["group1", "group2"]
 matrix = pd.DataFrame()
 for group in groups:
        out = fruit_df["fruits"].isin(df[group]).astype(int)
        matrix = pd.concat([matrix, out], axis = 1)
 matrix.columns = groups
 matrix = matrix.rename(index = fruit_df["fruits"]) 

结果:

matrix
        group1  group2
orange       1       1
banana       1       1

我想要的是:

 matrix
        group1  group2
 orange      1       1
 banana      2       1

推荐答案

这是您可以尝试的方法之一

Here's one of the way you could try

temp_df = pd.melt(df, var_name='group', value_name='fruits')
temp_df['count'] = 1
df_count = temp_df.pivot_table(index=['fruits'], columns=['group'], values='count', aggfunc=np.sum).reset_index()
matrix = fruits_df.merge(df_count)
matrix.set_index('fruits')
print(matrix)

结果是

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