Pivot table reindexing in pandas

Question

Having a dataframe as below:

df1 = pd.DataFrame({'Name1':['A','Q','A','B','B','C','C','C','E','E','E'],
                    'Name2':['B','C','D','C','D','D','A','B','A','B','C'],'Marks2':[10,20,6,50, 88,23,140,9,60,65,70]})
df1

#created a new frame
new=df1.loc[(df1['Marks2'] <= 50)]
new

#created a pivot table
temp=new.pivot_table(index="Name1", columns="Name2", values="Marks2")
temp

I tried to re-index the pivot table.

new_value=['E']
order = new_value+list(temp.index.difference(new_value))
matrix=temp.reindex(index=order, columns=order)
matrix

But the values related to ‘E’ is not present in pivot table. dataframe df1 contains values related with E. I need to add the value related to E in the pivot_table

Expected output:

Asked By: Jack

||

Source

Answer 1

Based on the comments my understanding of the intended result:

    E     A     B     C     D
E NaN  60.0  65.0  70.0   NaN
A NaN   NaN  10.0   NaN   6.0
C NaN   NaN   9.0   NaN  23.0
Q NaN   NaN   NaN  20.0   NaN

Code:
Activate the inlcuded #print() statements to see what the steps do.
Especially at the header ‘formatting’ in the end you may adapt acc. your needs.

import pandas as pd
import numpy as np

df1 = pd.DataFrame({'Name1':['A','Q','A','B','B','C','C','C','E','E','E'],
                    'Name2':['B','C','D','C','D','D','A','B','A','B','C'],
                    'Marks2':[10,20,6,50, 88,23,140,9,60,65,70]})

df1['Marks2'] = np.where( (df1['Marks2'] >= 50) & (df1['Name1'] != 'E'), 
                         np.nan, df1['Marks2'])
#print(df1)

temp=df1.pivot_table(index="Name1", columns="Name2", values="Marks2")
#print(temp)

name1_to_move = 'E'

# build new index with name1_to_move at the start (top in df idx)
idx=temp.index.tolist() 
idx.pop(idx.index(name1_to_move))
idx.insert(0, name1_to_move)
# moving the row to top by reindex
temp=temp.reindex(idx)
#print(temp)

temp.insert(loc=0, column=name1_to_move, value=np.nan)
#print(temp)

temp.index.name = None
#print(temp)

temp = temp.rename_axis(None, axis=1)
print(temp)

Answered By: MagnusO_O

Pivot table reindexing in pandas

Question:

Answers: