python (list,dataframe) 去重

1.list

1，set 不能保证顺序

new_list = list(set(old_list))

2，循环

new_list = []
for value in old_list:
    if value not in new_list:
        new_list.append(value)

3，字典(推荐)可以保证顺序

new_list = list(dict.fromkeys(old_list))

2.dataframe

1,series

df = pd.DataFrame({'a':[1,2,3,4,5,4,3,2,1]})
df_1 = df.drop_duplicates()
df_2 = df.drop_duplicates(keep=False)

keep = False 是指重复的一个都不要

image.png

2，dataframe

df = pd.DataFrame({'a':[1,2,3,4,5,4,3,2,1],'b':list(range(9))})
df_1 = df.drop_duplicates()
df_2 = df.drop_duplicates(keep=False)
df_3 = df.drop_duplicates(['a'])
df_4 = df.drop_duplicates(['a','b'])

不加列名默认是全部.png
可加多个列名.png