Python 将3列合并为一列

我有以下代码：

input= pd.DataFrame({'Police District Name': ['WHEATON', 'SILVER SPRING', 'BETHESDA','GERMANTOWN','WHEATON','MONTGOMERY VILLAGE'], 
                   'cn1': ['Crime Against Person', 'Crime Against Person', 'Crime Against Person','other','other','other'],
                  'cn2': ['Aggravated Assault', 'bla', 'bla','blaa','bla','one more  bla'],
                   'cn3': ['Aggravated Assault', 'bla', 'bla','blaa','bla','one more  bla'],

                    })
input

期望输出：

output= pd.DataFrame({'Police District Name': ['WHEATON', 'SILVER SPRING', 'BETHESDA','GERMANTOWN','WHEATON','MONTGOMERY VILLAGE'], 
                       'total crime number':[6,3,3,3,6,3],

                    })
output

我怎么能得到这个？。

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谢谢大家!

如果

cn1

，

cn2

中的每个值都填充了犯罪，则可以使用列数。其思想是通过

value\u counts

构造一系列计数，并乘以

cnx

列的数量。然后映射到您的数据帧

counts = df['Police District Name'].value_counts() * (len(df.columns) - 1)
df['total crime number'] = df['Police District Name'].map(counts)

print(df[['Police District Name', 'total crime number']])

  Police District Name  total crime number
0              WHEATON                   6
1        SILVER SPRING                   3
2             BETHESDA                   3
3           GERMANTOWN                   3
4              WHEATON                   6
5   MONTGOMERY VILLAGE                   3

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值6、3等从何而来？@KenDekalb每个警区的犯罪计数，例如：WHEATON total crimes=6“cn1用于犯罪名称1等”