How to subtract 2 string columns in a Pyspark dataframe

Question

Below is the scenario: Consider a Pyspark dataframe having 2 columns like below:

{ fullname: facebook, lastname: book }

I want a new column firstname by subracting fullname and lastname like below

{ firstname:face, lastname:book }

Answer 1

df  = spark.createDataFrame(
  [
('facebook','book')
  ], ['fullname','lastname'])

df.withColumn('firstname', F.expr("regexp_replace(fullname,lastname,'')")).show()

+--------+--------+---------+
|fullname|lastname|firstname|
+--------+--------+---------+
|facebook|    book|     face|
+--------+--------+---------+