Python Pandas - Iterating and adding data to blank column

Question

I am trying to iterate through a dataframe, classify each row and add the output to the end of the row in a new column.

It seems to be adding the same classification to every row

dfMach = pd.read_csv("C:/Users/nicholas/Desktop/machineSum.csv", encoding='latin-1')
dfNew = dfMach
dfNew["Classification"] = ""

for index, row in dfMach.iterrows():
    aVar = dfMach['Summary'].iat[0]
    aClass = cl.classify(aVar)
    dfNew['Classification'] = aClass

Where am I going wrong?

Thank you

But wait a second. You are trying to fill all the data in new classification with the classify value returned from first value of summary ? Will that be of any use ? — Bharath M Shetty
– Bharath M Shetty, Commented Nov 13, 2017 at 11:39
May be you meant row['Summary'] instead of dfMach['Summary']. Its better you go for apply — Bharath M Shetty
– Bharath M Shetty, Commented Nov 13, 2017 at 11:44
Why use index when you can directly access row['Summary'] ? — Bharath M Shetty
– Bharath M Shetty, Commented Nov 13, 2017 at 11:47
Oh ok! so I can remove the .iat part and just have row['Summary], thank you! — Nicholas
– Nicholas, Commented Nov 13, 2017 at 11:48

Bharath M Shetty · Accepted Answer · 2017-11-13 11:54:09Z

5

Use apply instead of looping explicitly i.e

 dfMach['Classification'] = dfMach['Summary'].apply(cl.classify)

A couple of simple mistake to be corrected in your code and a bit of improvement i.e

dfNew = dfMach.copy() # dfNew = dfMach This will not let you create a new copy so you have to use dfMach.copy()

dfNew["Classification"] = ""

for index, row in dfMach.iterrows(): 
    # As @jez suggested we need to use loc for assignemnt 
    dfNew.loc[index, 'Classification'] = cl.classify(row['Summary'])

edited Nov 13, 2017 at 11:54

answered Nov 13, 2017 at 11:36

Bharath M Shetty

30.6k6 gold badges65 silver badges111 bronze badges

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

4 Comments

Nicholas Over a year ago

Thank you, I will give it a go! :)

Nicholas Over a year ago

I understand what you mean now. Thank you!

Bharath M Shetty Over a year ago

@ScoutEU there are bit of things you need to take care of so check out the updated answer : )

Nicholas Over a year ago

Bharath, thank you for taking the time to clean up my code and for your help in this. Both you and Jezrael have been great and are reasons why I love the community on this website so much, there are no comparisons!

Collectives™ on Stack Overflow

Python Pandas - Iterating and adding data to blank column

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related