如何通过计算熊猫数据框中的值来创建新系列？

Question

I have a pandas data frame which looks like this:

like_count  dislike_count   dog_video   cat_video   bird_video  other_animal_video  animal_category
1000          500            True          False       False         False               dog
5500          300            False         True        False         False               cat
2300          100            False         False       True          False               bird
1100          200            False         False       False         True                other

What I need to do is to create a new series by calculating the number of dog, cat, bird and other in the animal_category . My new series should look like this:

animal_names number of animals  
dog                50
cat                20
bird               15
other              30

How can I do this?

Answer 1

另一种选择（来自@Quang Hoang的答案）是使用groupby()

output_df = df.groupby(['animal_category'],as_index=False)['like_count'].count().rename(columns={'like_count':'number of animals'})