python pandas比较两列并返回结果

Question

I have two dataframes as below. I added key column to both so that I can get Cartesian joint. I want to compare each value from df3 data frame's BEN_NAME2 column with df4 data frames's names2 column. My original plan was to perform Cartesian joint and to check whether there are any matching values. But both of my data frames are quite big and I am getting a memory error when I try to join.

I would like to do this operation one cell at a time from the column BEN_NAME2 . I would like to create a new column in df3 which would give me row index from df3 if the exact match was found.

For example, df3 will get two new columns, column match with values (0,1,0) and column matching_row_index with values (0,3,0) because jones value from the second row has a match in the df4 data frame

sales = [{'key': 0, 'BEN_NAME2': '150 jones'},
         {'key': 0,  'BEN_NAME2': 'jones'},
         {'key': 0,  'BEN_NAME2': '50'}]
df3 = pd.DataFrame(sales)

sales = [{'key': 0, 'names2': 'xyc'},
         {'key': 0,  'names2': 'fsdfa'},
         {'key': 0,  'names2': 'jones'}]
df4 = pd.DataFrame(sales)

my main goal is get output at a relatively fast rate.

Answer 1

Use iloc() in loop. This function allows you to navigate a data frame like an array.

for i in range(0,10):
    A=df['Ben_names'].iloc[i]
    B= df['column_name'].iloc[i]
    #write the conditional statement using if and value to be inserted is var

    df.['column_nmae2'].iloc[i]=var