How do I combine two different row string values into a single new row value?

Question:

I have two rows of a dataframe likeso:

   Jan  Feb
a   1    3
b   2    4

I want to create a new dataframe row that combines the two rows (by name because I have to do this for multiple sets of rows of the df) into one row like this:

   Jan  Feb
a   1    3
b   2    4  
c  1/2  3/4

And I do not mean just division as the data types of the actual values are string, I want to concatenate. I feel like there has to be an obvious solution but nothing I have found online is working.

Asked By: Rachel Porter

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Source

Answers:

You could do something like this:

df.loc['c', :] = df.apply(lambda x: '/'.join(map(str,x)))

Ouput:

   Jan  Feb
a  1.0  3.0
b  2.0  4.0
c  1/2  3/4
Answered By: Rabinzel

Try this:

df.loc['c', :] = df.apply(lambda x: f"{x[0]}/{x[1]}")
print(df)

Output:

   Jan  Feb
a  1.0  3.0
b  2.0  4.0
c  1/2  3/4
Answered By: I'mahdi

You can concatenate the strings by first converting the values to strings and then combining them with the + operator.

import pandas as pd    
df = pd.DataFrame({'Jan': [1, 2], 'Feb': [3, 4]}, index=['a', 'b'])    
df.loc['c'] =df.loc['a'].astype(str) + '/' + df.loc['b'].astype(str)
Answered By: amjad khatabi

You can do something like this: (option without loc, don’t meen it’s better)

df['c'] = df.apply(lambda x: x['a'] + '/' + x['b'], axis=1)
df.set_index('name', inplace=True)
df = df.transpose()
Answered By: Jonatas Delatorre

Try something like this:

def concat_rows(df,idx,sep="/"):
    return [sep.join(l) for l in df.loc[idx].values]

df.loc["new_row"] = concat_rows(df,["a","b"],sep="/")

Explanation:

This function allows you to choose the rows to concat and the separator between strings.

Args:

df: pandas dataframe

idx: list of index of rows to concat. Example: ["a","b"]

sep: separator between strings. Default = "/"

RESULT:

         JAN    FEB
a          1     3
b          2     4
new_row   1/3   2/4
Answered By: Pedro Rocha