How to replace all non-NaN entries of a dataframe with 1 and all NaN with 0
Use: df.fillna(0)
to fill NaN with 0.
I have a dataframe with 71 columns and 30597 rows. I want to replace all non-nan entries with 1 and the nan values with 0.
Initially I tried for-loop on each value of the dataframe which was taking too much time.
Then I used data_new=data.subtract(data) which was meant to subtract all the values of the dataframe to itself so that I can make all the non-null values 0. 
But an error occurred as the dataframe had multiple string entries.