Pandas - groupby with condition

Question

I would like to groupby my pandas dataframe based on a given range condition. For example:

Number, Amount
1, 5
2, 10
3, 11
4, 3
5, 5
6, 8
7, 9
8, 6

Range conditions:

1 till 4 (included), named A: 5+10+11+3 = 29

5 and higher, named B: 5+8+9+6 = 28

Desired outcome:

Number, Amount
A, 29
B, 28

EDIT: Thanks for the great solutions. I would like to be able to add more range conditions if needed, so 5-7 and 8 alone should also be a possibility. Is it possible to keep that flexible?

Answer 1

You can use pd.cut also, helpful if you more that two labels and ranges:

df.groupby(pd.cut(df['Number'], 
                  bins=[0,4,np.inf], 
                  labels=['A', 'B']))['Amount'].sum().reset_index()

Output:

  Number  Amount
0      A      29
1      B      28