Replacing values that match certain string in dataframe

Question

I am trying to replace certain data in the data frame to include the additional 'F'.

The code should look like this:

if testdata['pfType'] =='NK225M'|testdata['pfType'] == 'TOPIXM':
    testdata['pfType'] = ' testdata['pfType'] & 'F';

I tried to do this:

testdata['pfType'][testdata['pfType'] == 'NK225M'] = 'NK225MF'
testdata['pfType'][testdata['pfType'] == 'TOPIXM'] = 'TOPIXMF'

But it is not changing the values, what is the best way to add the 'F' to the strings if it is NK225M or TOPIXM.

jezrael · Accepted Answer · 2019-01-28 06:49:52Z

5

Use isin for test values of list and if match condition add F:

testdata = pd.DataFrame({'pfType':['NK225M','TOPIXM','AAA']})

vals = ['NK225M','TOPIXM']
testdata.loc[testdata['pfType'].isin(vals), 'pfType'] += 'F'
print (testdata)
    pfType
0  NK225MF
1  TOPIXMF
2      AAA

Another solutions with Series.mask or numpy.where:

testdata['pfType'] = testdata['pfType'].mask(testdata['pfType'].isin(vals),
                                             testdata['pfType'] + 'F')

testdata['pfType'] = np.where(testdata['pfType'].isin(vals), 
                              testdata['pfType'] + 'F', 
                              testdata['pfType'])

edited Jan 28, 2019 at 6:49

answered Jan 28, 2019 at 6:44

jezrael

868k103 gold badges1.4k silver badges1.3k bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Rakesh · Accepted Answer · 2019-01-28 06:45:14Z

3

Use numpy.where

Ex:

import pandas as pd
import numpy as np

testdata = pd.DataFrame({"pfType": ['NK225M', 'TOPIXM', "Hello", "World"]})
testdata['pfType'] = np.where((testdata['pfType'] == "TOPIXM") | (testdata['pfType'] == 'NK225M'), testdata['pfType']+"F", testdata['pfType'])
print(testdata)

Output:

    pfType
0  NK225MF
1  TOPIXMF
2    Hello
3    World

answered Jan 28, 2019 at 6:45

Rakesh

82.9k17 gold badges85 silver badges122 bronze badges

Comments

Sociopath · Accepted Answer · 2019-01-28 06:44:12Z

1

Use np.where

testdata['pfType'] = np.where(testdata['pfType']=='NK225M', 'NK225MF', testdata['pfType'])
testdata['pfType'] = np.where(testdata['pfType']=='TOPIXM', 'TOPIXMF', testdata['pfType'])

answered Jan 28, 2019 at 6:44

Sociopath

13.4k22 gold badges53 silver badges82 bronze badges

Comments

shingote · Accepted Answer · 2019-01-28 06:43:10Z

0

To modify dataframe use below code.

  testdata.at['pfType', testdata['pfType'] == 'NK225M'] = 'NK225MF'

(ref.)

answered Jan 28, 2019 at 6:43

shingote

12 bronze badges

Collectives™ on Stack Overflow

Replacing values that match certain string in dataframe

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related