Creating New columns by comparing existing columns(Copy Issue)-CodePudding

I have some issue in my code.

I tried to create new columns by comparing existing two columns

Here is my example Dataframe

occ_2019_pe:

index            occ10        occ10_t1     
0                 20           20   
1                 20           12   
2                 30           30       
3                 40           34

I want to generate new column by using this code

occ_2019_pe['occ_change'] = np.where(occ_2019_pe['occ10']==occ_2019_pe['occ10_t1'], 0, 1)

However, it generate this issue,

<ipython-input-25-f48cdb1733d5>:1: SettingWithCopyWarning: 
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead

See the caveats in the documentation: https://pandas.pydata.org/pandas-docs/stable/user_guide/indexing.html#returning-a-view-versus-a-copy
  occ_2019_pe['occ_change'] = np.where(occ_2019_pe['occ10']==occ_2019_pe['occ10_t1'], 0, 1)

How could I solve this?

CodePudding user response：

Use assign.

occ_2019_pe = occ_2019_pe.assign(occ_change=np.where(occ_2019_pe['occ10']==occ_2019_pe['occ10_t1'], 0, 1))

CodePudding user response：

When I run code with your small example then I don't get this error.

But maybe you should use suggested .loc[row_indexer,col_indexer] = value

occ_2019_pe.loc[:,'occ_change'] = np.where(occ_2019_pe['occ10']==occ_2019_pe['occ10_t1'], 0, 1)