Splitting a row in a PySpark Dataframe into multiple rows

Question

I currently have a dataframe where one column is of type "a b c d e ...". Call this column col4

I would like to split a single row into multiple by splitting the elements of col4, preserving the value of all the other columns.

So, for example, given a df with single row:

|col1[0] | col2[0] | col3[0] | a b c |

I would like the output to be:

|col1[0] | col2[0] | col3[0] | a | 
|col1[0] | col2[0] | col3[0] | b |
|col1[0] | col2[0] | col3[0] | c |

Using the split and explode functions, I have tried the following:

d = COMBINED_DF.select(col1, col2, col3, explode(split(my_fun(col4), " ")))

However, this results in the following output:

|col1[0] | col2[0] | col3[0] | a b c |
|col1[0] | col2[0] | col3[0] | a b c |
|col1[0] | col2[0] | col3[0] | a b c |

which is not what I want.

Answer 1

Here's a reproducible example:

# Create dummy data
df = sc.parallelize([(1, 2, 3, 'a b c'),
                     (4, 5, 6, 'd e f'),
                     (7, 8, 9, 'g h i')]).toDF(['col1', 'col2', 'col3','col4'])


# Explode column
from pyspark.sql.functions import split, explode
df.withColumn('col4',explode(split('col4',' '))).show()
+----+----+----+----+
|col1|col2|col3|col4|
+----+----+----+----+
|   1|   2|   3|   a|
|   1|   2|   3|   b|
|   1|   2|   3|   c|
|   4|   5|   6|   d|
|   4|   5|   6|   e|
|   4|   5|   6|   f|
|   7|   8|   9|   g|
|   7|   8|   9|   h|
|   7|   8|   9|   i|
+----+----+----+----+