user113531 - 1 year ago 59

Python Question

I have a dataframe with multiple group columns and a value column.

`a b val`

0 A C 1

1 A D 1

2 A D 1

3 A D 2

4 B E 0

For any one group, for eg

`a==A`

`b==C`

`value_counts`

`a b val counts`

0 A C 1 1

1 A D 1 2

2 A D 2 1

2 B E 0 1

Answer Source

is that what you want?

```
In [47]: df.groupby(['a','b','val']).size().reset_index()
Out[47]:
a b val 0
0 A C 1 1
1 A D 1 2
2 A D 2 1
3 B E 0 1
```

or this?

```
In [43]: df['counts'] = df.groupby(['a','b'])['val'].transform('size')
In [44]: df
Out[44]:
a b val counts
0 A C 1 1
1 A D 1 3
2 A D 1 3
3 A D 2 3
4 B E 0 1
```