Add a comment row to a row (at the same index) in a Pandas Dataframe-CodePudding

Specifically, I'm looking for a way to iterate over a Dataframe, and add such a row in case a condition is met. The added row will have the same index as the row it was added to. Couldn't find relevant information.

Code and data for the purpose of this question:

a = {'a': [1,3,5,7], 'b': [2,4 ,6, 8], 'c': [3, 5,7,9]}
b = pandas.DataFrame(a)
b
Out[4]: 
a  b  c
0  1  2  3
1  3  4  5
2  5  6  7
3  7  8  9

If for the sum of the digits in a row: sum_row % 4 = 0, the program adds a row to that row that has the same index as the initial row. The added row is not divided into columns, but rather it consists of a single cell with a comment.
Desired resulting dataframe should look like that:

a  b  c
0  1  2  3
1  3  4  5
   sum_row % 4 yields no remainder
2  5  6  7
3  7  8  9
   sum_row % 4 yields no remainder

    a  b  c
0  1  2  3
1  3  4  5
1  sum_row % 4 yields no remainder
2  5  6  7
3  7  8  9
3  sum_row % 4 yields no remainder

Thanks.

CodePudding user response：

this is my interpretation: He needs evaluate "mod 4" (% 4) in every row. This is my old school loop into DATAFRAME using iterrows. With this code you can create a new DF into Loop, or create a D column with % 4 result.

import pandas as pd

# Loop in DATAFRAME

a = {'a': [1,3,5,7], 'b': [2,4 ,6, 8], 'c': [3, 5,7,9]}
b = pd.DataFrame(a)

# Print Data Frame
# print (b) 
for index, x in b.iterrows():
  # Print Line
  print (x['a'] , x['b'] , x['c'] )
  result = (x['a']   x['b']   x['c'] ) % 4
  if result == 0:
    # Print Result
    print ('sum_row % 4 yields no remainder')

CodePudding user response：

The desired output as shown is not possible. You can do something like this:

import pandas as pd

spam = {'a': [1,3,5,7], 'b': [2,4 ,6, 8], 'c': [3, 5,7,9]}
df = pd.DataFrame(spam)
df['remainder'] = (df.sum(axis=1) % 4).astype(bool)
df['comment'] = df.remainder.apply(lambda x: 'remainder' if x else 'no remainder')
print(df)

output

   a  b  c  remainder      comment
0  1  2  3      True     remainder
1  3  4  5     False  no remainder
2  5  6  7      True     remainder
3  7  8  9     False  no remainder