How to use python to select all rows with minimum values for each group in a table

X	Y	Val	GrpID
414995.44	5813554.46	2.848	1
414995.25	5813554.17	2.847	1
414995.40	5813554.39	2.840	1
414995.35	5813554.32	2.840	1
414995.31	5813554.25	2.840	1
414995.21	5813554.11	2.856	1
414995.15	5813554.03	2.876	1
414995.13	5813554.96	2.888	1
414976.71	5813526.54	0.768	2
414976.62	5813526.39	0.744	2
414976.37	5813526.03	0.712	2
414976.33	5813525.96	0.712	2
414976.23	5813525.81	0.728	2
414976.13	5813525.67	0.736	2
414976.08	5813525.59	0.745	2

I want the results to be as shown below:

X	Y	Val	GrpID
414995.40	5813554.39	2.840	1
414995.35	5813554.32	2.840	1
414995.31	5813554.25	2.840	1
414976.37	5813526.03	0.712	2
414976.33	5813525.96	0.712	2

Solution

Kindly try using the return of a groupby as argument for the slicing:

df[df['Val'].isin(df.groupby('GrpID')['Val'].min())]

Returns:

            X           Y    Val  GrpID
2   414995.40  5813554.39  2.840      1
3   414995.35  5813554.32  2.840      1
4   414995.31  5813554.25  2.840      1
10  414976.37  5813526.03  0.712      2
11  414976.33  5813525.96  0.712      2