add columns different length pandas

Question

I have a problem with adding columns in pandas. I have DataFrame, dimensional is nxk. And in process I wiil need add columns with dimensional mx1, where m = [1,n], but I don

Answer 1

I had the same issue, two different dataframes and without a common column. I just needed to put them beside each other in a csv file.

• Merge: In this case, "merge" does not work; even adding a temporary column to both dfs and then dropping it. Because this method makes both dfs with the same length. Hence, it repeats the rows of the shorter dataframe to match the longer dataframe's length.
• Concat: The idea of The Red Pea didn't work for me. It just appended the shorter df to the longer one (row-wise) while leaving an empty column (NaNs) above the shorter df's column.
• Solution: You need to do the following:

df1 = df1.reset_index()
df2 = df2.reset_index()
df = [df1, df2]
df_final = pd.concat(df, axis=1)

df_final.to_csv(filename, index=False)

This way, you'll see your dfs besides each other (column-wise), each of which with its own length.