如何获取 python 中某一列的每个类别的计数？

Question

I have a data frame with a categorical column with several levels. I would like to count how many different categories there are per each day.

Timestamp   Type   value1    value2
2020-08-31  Orange  3.4       5.7
2020-08-31. Red     7.9       4.5
2020-08-31  Purple  6.3       2.7
2020-09-01  Yellow  3.4       1.6

The values are the mean of these values per each day based on the type. Now I'd like to add some columns with the counting of each type per day.

Answer 1

Please add an example of your output. Possibly this is what you want.

amount_per_day = df.groupby('Timestamp')['Type'].nunique()
result = df.merge(amount_per_day, on='Timestamp')