Python: unable to compare strings in dataframes

Question

I am trying to lookup string values in two dataframes and I am using Pandas library.

The first dataframe - df_transactions has a list of error codes in the column 'ErrList'

The second dataframe - df_action has a list of errors in one column 'CODE' and the corresponding error in the column 'ACTION'.

I am trying to compare the two strings from these dataframes as below:

ActionLookup_COL = []
ActionLookup = []
for index, transactions in df_transactions.iterrows():
        errorList = transactions['ErrList']
        for index, errorCode in df_action.iterrows():
            eCode = errorCode['Code']
            eAction = errorCode['Action']
            if eCode ==errorList:
                ActionLookup.append(eAction)

        ActionLookup_COL.append(ActionLookup)

df_results['ActionLookup'] = pd.Series(shipmentActionLookup_COL, index=df_results.index)

When I print the dataframe df_results['ActionLookup'], I do not get the action code corresponding to the error code. Please let me know how can I compare the strings in these dataframes

Thanks for your time!

jezrael · Accepted Answer · 2016-11-14 08:24:19Z

1

IIUC you need merge:

pd.merge(df_transactions, df_action, left_on='ErrList', right_on='Code')

Sample:

df_transactions = pd.DataFrame({'ErrList':['a','af','e','d'],
                                'col':[4,5,6,8]})

print (df_transactions)
  ErrList  col
0       a    4
1      af    5
2       e    6
3       d    8

df_action = pd.DataFrame({'Code':['a','af','u','m'],
                          'Action':[1,2,3,4]})

print (df_action)
   Action Code
0       1    a
1       2   af
2       3    u
3       4    m

df_results = pd.merge(df_transactions, df_action, left_on='ErrList', right_on='Code')
print (df_results)
  ErrList  col  Action Code
0       a    4       1    a
1      af    5       2   af

print (df_results['Action'])
  ErrList  col  Action Code
0       a    4       1    a
1      af    5       2   af

edited Nov 14, 2016 at 8:24

answered Nov 14, 2016 at 7:36

jezrael

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