Explode multiple columns to rows in pyspark

I have the below spark dataframe.

Name     age     subject        parts
xxxx     21      Maths,Physics  I
yyyy     22      English,French I,II

I am trying to explode the above dataframe in both subject and parts like below.

Expected output:

Name     age     subject        parts
xxxx     21      Maths          I
xxxx     21      Physics        I
yyyy     22      English        I
yyyy     22      English        II
yyyy     22      French         I
yyyy     22      French         II

I tried using array.zip for subject and parts and then tried to explode using the temp column, but I am getting null values in the place where there is only one part.

Is there a way to achieve this in Pyspark.