How to merge two dataframes with Pandas?

Question

I am using Pandas to merge two dataframes obtained from Psychopy.

y = ["key_resp_0.keys", "key_resp_0.rt"] #some columns I want in my final dataframe
df = pd.DataFrame(myData)
columns = df.columns.values.tolist() 
df2 = df.reindex(columns = y, fill_value='')
df3 = pd.merge(df2,df)

This is the error I get:

type object argument after * must be an iterable, not itertools.imap

I checked what type of dataframes I have:

print(type(df))
print(type(df2))

This is the result:

<class 'pandas.core.frame.DataFrame'> #df
<class 'pandas.core.frame.DataFrame'> #df2

Following some info found in other posts, I also tried to convert df and df2 into tuples and then doing the merge .

df = df.apply(tuple) 
df2 = df2.apply(tuple)
df3 = pd.merge(df2,df)

Then I get a different error

can not merge DataFrame with instance of type <class 'pandas.core.series.Series'>

Do you know what could be a way to merge these two dataframes?

Answer 1

Check this thread . Literally, I see this question asked every few days. Official docs are rather covering this as well. RTFM bro.

Answer 2

I think I managed to find a solution.

In my dataframe df there was a possibly empty string (when opening df as a .csv file, one cell contained only [] ). Now I am assigning to that cell a value of zero and the merge function seems to work properly.