Save multiple dataframes to the same file, one after the other

user_8684461 0
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Lets say I have three dfs

x,y,z
0,1,1,1
1,2,2,2
2,3,3,3

a,b,c
0,4,4,4
1,5,5,5
2,6,6,6

d,e,f
0,7,7,7
1,8,8,8
2,9,9,9

How can I stick them all together so that i get:

x,y,z
0,1,1,1
1,2,2,2
2,3,3,3
a,b,c
0,4,4,4
1,5,5,5
2,6,6,6
d,e,f
0,7,7,7
1,8,8,8
2,9,9,9

I am not fussed if it's in a df or not hence I haven't included a new index. Essentially I just want to glue n amount of dfs together to save me having to copy and paste the data into an excel sheet myself.

pandas dataframe python
3 Answers

If you want to save all your dataframes in the same file one after the other, use a simple loop with to_csv and use the file append mode (a):

dfs = [df1, df2, df3]

for d in dfs:
    d.to_csv('out.csv', mode='a')

NB. the initial file must be empty or non existent

output out.csv:

,x,y,z
0,1,1,1
1,2,2,2
2,3,3,3
,a,b,c
0,4,4,4
1,5,5,5
2,6,6,6
,d,e,f
0,7,7,7
1,8,8,8
2,9,9,9
user_163434640

Have a look at the to_csv() method of DataFrame.

print(df1.to_csv(index=False))
print(df2.to_csv(index=False))
print(df3.to_csv(index=False))

That being said, there is a to_excel() method as well that may solve the potential XY Problem referenced in the comments.

user_22210010

You might try this:

start_df = df1
other_dfs = [df2, df3]
new_df = pd.concat([start_df, *[x[::-1].append(dict(zip(x.columns, x.columns)), ignore_index=True)[::-1].reset_index(drop=True).set_axis(start_df.columns, axis=1) for x in other_dfs]], ignore_index=True)

Output:

>>> new_df
    x  y  z
0   1  1  1
1   2  2  2
2   3  3  3
3   a  b  c
4   4  4  4
5   5  5  5
6   6  6  6
7   d  e  f
8   7  7  7
9   8  8  8
10  9  9  9

Basically what we're doing here is, for each df in other_dfs, we reverse it, append the columns of that dataframe to the end, re-reverse it, change its columns to match start_df's columns, and then we concatenate them all together.

Admin1
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