Pandas groupby 计数值 > 0

Question

I have a pandas df of the following format

MATERIAL    DATE         HIGH    LOW
AAA       2022-01-01     10      0
AAA       2022-01-02     0       0
AAA       2022-01-03     5       2
BBB       2022-01-01     0       0
BBB       2022-01-02     10      5
BBB       2022-01-03     8       4

I am looking to transform it such that I land up with the below result

MATERIAL      HIGH_COUNT    LOW_COUNT 
AAA            2              1         
BBB            2              2         

Essentially for "HIGH_COUNT" and "LOW_COUNT" I want to count the number of occurrences that column was greater than 0, grouped by "MATERIAL" . I have tried to do df.groupby(['MATERIAL']).agg<xxx> but I am unsure of the agg function to use here.

Edit:

I used

df.groupby(['MATERIAL']).agg({'HIGH':'count', 'LOW':'count}) 

but this counts even the 0 rows.

Answer 1

You could create a boolean DataFrame and groupby + sum :

out = df[['HIGH', 'LOW']].gt(0).groupby(df['MATERIAL']).sum().add_suffix('_COUNT').reset_index()

Output:

  MATERIAL  HIGH_COUNT  LOW_COUNT
0      AAA           2          1
1      BBB           2          2