Python: get a frequency count based on two columns (variables) in pandas dataframe some row appers
PythonPandasGroup ByDataframePython Problem Overview
Hello I have the following dataframe.
Group Size
Short Small
Short Small
Moderate Medium
Moderate Small
Tall Large
I want to count the frequency of how many time the same row appears in the dataframe.
Group Size Time
Short Small 2
Moderate Medium 1
Moderate Small 1
Tall Large 1
Python Solutions
Solution 1 - Python
You can use groupby's size:
In [11]: df.groupby(["Group", "Size"]).size()
Out[11]:
Group Size
Moderate Medium 1
Small 1
Short Small 2
Tall Large 1
dtype: int64
In [12]: df.groupby(["Group", "Size"]).size().reset_index(name="Time")
Out[12]:
Group Size Time
0 Moderate Medium 1
1 Moderate Small 1
2 Short Small 2
3 Tall Large 1
Solution 2 - Python
Update after pandas 1.1 value_counts now accept multiple columns
df.value_counts(["Group", "Size"])
You can also try pd.crosstab()
Group Size
Short Small
Short Small
Moderate Medium
Moderate Small
Tall Large
pd.crosstab(df.Group,df.Size)
Size Large Medium Small
Group
Moderate 0 1 1
Short 0 0 2
Tall 1 0 0
EDIT: In order to get your out put
pd.crosstab(df.Group,df.Size).replace(0,np.nan).\
stack().reset_index().rename(columns={0:'Time'})
Out[591]:
Group Size Time
0 Moderate Medium 1.0
1 Moderate Small 1.0
2 Short Small 2.0
3 Tall Large 1.0
Solution 3 - Python
Other posibbility is using .pivot_table() and aggfunc='size'
df_solution = df.pivot_table(index=['Group','Size'], aggfunc='size')