When using groupby, change the type to distort the value.

[JovanVeljanoski]

Discussed in https://github.com/vaexio/vaex/discussions/2131

^{Originally posted by tommyhj217 July 26, 2022} Hi DataFrame delay_time has values from -276 to 111 and dtype=int64. The number of values is 206.

df_delaytime_data = vdf_2.groupby(['delay_time'], agg={'cnt':'count'})

However, if you do groupby, the dtype of the column is changed to int8, and the value of -128 or higher is changed to positive.

Is this a problem with groupby? How can we solve it?

Thanks Hyunjun