concatenate dataframe with dataframe from list

Question

I want to concatenate a dataframe (df) with another dataframe that is stored in a list of dataframes.

dflist = [df1, df2, df3]

What I want is a dataframe like below

new_dflist = [df+df1, df+df2, df+df3]

new_dflist = []
for n in dflist:
    new_dflist.append(pd.concat(df, dflist[n]))

but I get the error message
TypeError: list indices must be integers or slices, not DataFrame

I also tried with enumerate but I get the error message
TypeError: list indices must be integers or slices, not tuple

Code-Apprentice · Accepted Answer · 2022-12-12 18:09:52Z

1

Try this:

dflist = [df1, df2, df3]
new_dflist=[]
for n in dflist:
    new_dflist.append(pd.concat([df, n]))

n is a dataframe and you are trying to put it in list index

edited Dec 12, 2022 at 18:09

Code-Apprentice

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answered Dec 12, 2022 at 6:02

Talha Tayyab

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Code-Apprentice · Accepted Answer · 2022-12-12 18:10:06Z

0

but I get the error, TypeError: list indices must be integers or slices, not DataFrame

That is because n is a dataframe, not an integer. You seem to think that for loop gives you the indexes in a list, but it actually gives you the items directly. Just change your code to use the dataframe from the for loop iterator:

new_dflist=[]
for new_df in dflist:
    new_dflist.append(pd.concat([df, new_df]))

Alternatively, you can do this in a single line with a list comprehension:

new_dflist=[pd.concat([df, new_df]) for new_df in dflist]

edited Dec 12, 2022 at 18:10

answered Dec 12, 2022 at 6:04

Code-Apprentice

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3 Comments

michan2378 Over a year ago

Thanks! This gave me an error "TypeError: first argument must be an iterable of pandas objects, you passed an object of type "DataFrame"" but this post helped me solve that problem!! link

Code-Apprentice Over a year ago

@michan2378 Thanks for the information. I updated my answer with a fix for that error. This also leads me to a question...is there a reason you don't concatenate all of the dataframes together into a single dataframe?

michan2378 Over a year ago

yes, I am making a program where the training data for the model is conditional. In this case, dataframe "df" contains data used to train all model the same, and in addition to that, I want to add conditional data that is in dataframes "df1, df2, df3".

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