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I am new to coding in Python. Currently, I am trying to analyse a dataframe containing multiple workflows. Each workflow has a different process steps for initiating and ending a workflow. In a simplified version, my data looks like the following:

   Workflow Initiate   End_1   End_2   End_3

0         1   Name_1      na  Name_1      na

1         2   Name_2      na      na      na

2         3   Name_3      na      na  Name_5

3         4   Name_4  Name_5      na      na

4         5       na      na      na  Name_5

For every workflow, I want to compare whether the name that ended the workflow is different as the name that initiated the workflow.

Iterating through the rows in the following way gives me the desired output:

for index, row in df.iterrows():

    if ((row['Initiate'] != 'na')

        and (row['Initiate'] == row['End_1']) |

            (row['Initiate'] == row['End_2']) |

            (row['Initiate'] == row['End_3'])

        ):

        print("Name end equals initiate")

    elif ((row['End_1'] == 'na') &

          (row['End_2'] == 'na') &

          (row['End_3'] == 'na')

         ):

        print("No name ended")

    else:

        print("Different name ended")



Name end equals initiate

No name ended

Different name ended

Different name ended

Different name ended

However, I want to add an extra column, say 'Analysis', in the dataframe that shows the above outcome behind every workflow.

For this I stuffed the code into a function:

def function_name(a, b, c, d):

    for index, row in df.iterrows():

        if ((a != 'na')

            and (a == b) |

                (a == c) |

                (a == d)

            ):

            return "Name end equals initiate"

        elif ((b == 'na') &

              (c == 'na') &

              (d == 'na')

             ):

            return "No name ended"

        else:

            return "Different name ended"



df['Analysis'] = function_name(row['Initiate'],

                               row['End_1'],

                               row['End_2'],

                               row['End_3'])



print(df)



   Workflow Initiate          ...            End_3              Analysis

0         1   Name_1          ...               na  Different name ended

1         2   Name_2          ...               na  Different name ended

2         3   Name_3          ...           Name_5  Different name ended

3         4   Name_4          ...               na  Different name ended

4         5       na          ...           Name_5  Different name ended

As you can see the output is different from the first analysis. I would like to add an extra column to my dataframe that gives me the same output as with the print statements.

You should avoid row-wise loops here. Your algorithm is vectorisable:

df = df.replace('na', np.nan)  # replace string 'na' with NaN for efficient processing

ends = df.filter(like='End')  # filter by columns with 'End'



match = ends.ffill(1).iloc[:, -1] == df['Initiate']  # find last Name in each End

nulls = ends.isnull().all(1)  # check which rows are all null



# apply vectorised conditional logic

df['Result'] = np.select([match, nulls], ['Name end equals initiate', 'No name ended'],

                         'Different name ended')



print(df)



   Workflow Initiate   End_1   End_2   End_3                    Result

0         1   Name_1     NaN  Name_1     NaN  Name end equals initiate

1         2   Name_2     NaN     NaN     NaN             No name ended

2         3   Name_3     NaN     NaN  Name_5      Different name ended

3         4   Name_4  Name_5     NaN     NaN      Different name ended

4         5      NaN     NaN     NaN  Name_5      Different name ended

Try to use np.select()

conditions = [

    (df['Initiate'] != 'na') & ((df['Initiate'] == df['End_1']) | (df['Initiate'] == df['End_2']) | (df['Initiate'] == df['End_3'])),

    (df['End_1'] == 'na') & (df['End_2'] == 'na') & (df['End_3'] == 'na')

] 



answers = ['Name end equals initiate','No name ended']   

df['Analysis'] = np.select(conditions, answers, default='Different name ended')