Python add string value between variables conditonally

Question

I have a dataframe :

    c1     c3    c4     c5
r1         this  and
r2  that   str         shld
r3  have         and

The white spaces are chosen to be blank (they were NaN values which I replaced with '' instead)

These strings within the data frame represents error messages, the string only appear when the error is present.

My desired output:

    c1     c3    c4     c5    Error_Message
r1         this  and          this also and
r2  that   str         shld   that also str also shld
r3  have         and          have also and

My current output:

    c1     c3    c4     c5    Error_Message
r1         this  and          also this also and also
r2  that   str         shld   that also str also also shld
r3  have         and          have also also and also

The code I am using:

df_calc['Health_Message'] = df_calc['c1'] + ' also ' + df_calc['c3']  +' also ' \
                                + df_calc['c4'] + ' also ' +  df_calc['c5']

Is there a more pythionic or reliable way to get rid of the unnecessary 'also''s .. there should only be an 'also' between error messages (string values). I am in over my head, thank you

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

You can do it like this:

import pandas as pd

x = {"c1":["", "that", "have"], "c3":["this", "str",""],"c4":["and", "", "and"],"c5":["", "shld", ""]}

df = pd.DataFrame.from_dict(x)
df["Error_Message"] = df.apply(lambda row: " also ".join([el for el in row if el]),axis=1)
print(df)

Output:

     c1    c3   c4    c5            Error_Message
0        this  and                  this also and
1  that   str       shld  that also str also shld
2  have        and                  have also and

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Jan 15, 2020 at 11:38

Boendal

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3 Comments

Boendal Over a year ago

@LlewellynHattingh What you mean doesn't change anything? It produce the desired output you wished for?

Llewellyn Hattingh Over a year ago

Hi, my apologies, I had to make some adjustments on my side to the dataframe. Afterwards, your code worked exactly as it should. Thanx so much! I appreciate the simplicity

Boendal Over a year ago

@LlewellynHattingh don't worry. I'm glad that it worked out.

Drako · Accepted Answer · 2020-01-15 11:29:16Z

1

This should help:

>>> a = '1'
>>> b = '2'
>>> c = [a, b]
>>> d = ' also '.join(c)
>>> d
'1 also 2'

In your case - make list of all line contents first - then join.

answered Jan 15, 2020 at 11:29

Drako

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3 Comments

Llewellyn Hattingh Over a year ago

Thanx, how will I go about making a list of all string values for each row?

Drako Over a year ago

pseudo code: c = [] and for each element c.append(element)

Drako Over a year ago

it can actually be any collection you can loop over and may be you are already doing it in your code - then just add join part :)

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