使用assign方法向alreadyexisting表添加列

Question

下面是出现的问题、代码和错误。排名前10位的电影有两个栏目，分别是收视率和名称

import babypandas as bpd
top_10_movies = top_10_movies = bpd.DataFrame().assign(
Rating = top_10_movie_ratings,
Name = top_10_movie_names
)

top_10_movies

You can use the assign method to add a column to an already-existing table, too. Create a new DataFrame called with_ranking by adding a column named "Ranking" to the table in top_10_movies

import babypandas as bpd
Ranking = my_ranking
with_ranking = top_10_movies.assign(Ranking)





TypeError                                 Traceback (most recent call last)
<ipython-input-41-a56d9c05ae19> in <module>
      1 import babypandas as bpd
      2 Ranking = my_ranking
----> 3 with_ranking = top_10_movies.assign(Ranking)

TypeError: assign() takes 1 positional argument but 2 were given

Answer 1

在使用assign时，它需要分配一个键，您可以执行以下操作：

with_ranking = top_10_movies.assign(ranking = Ranking)

下面是一个简单的示例进行检查：

df = pd.DataFrame({'col': ['a','b']})
ranks = [1, 2]

df.assign(ranks) # causes the same error
df.assign(rank = ranks) # works