python之用字典實現代換， map 函數

 

用字典實現代換

 

# 創建字典, 數據框中的值爲 key， 用 value 替換

map_dic = {'key1':'value1', 'key2':'value2'}
df['column_name'] = df['column_name'].map(map_dic)


# 下面是將一列的元素編序號做鍵值對, 可忽略
map_dic = {}
i = 0
for r in df['column_name']:
    if r not in map_dic:
        map_dic[r] = i
        i += 1