Added pyspark chaining examples

Author: pybokeh

PyData/bookmarks.txt

@@ -11,6 +11,7 @@ https://hakibenita.com/postgresql-unknown-features
 # PySpark
 https://jacobcelestine.com/knowledge_repo/colab_and_pyspark/
 https://sparkbyexamples.com/
+chaining: https://mungingdata.com/pyspark/chaining-dataframe-transformations/
 https://phoenixnap.com/kb/install-spark-on-ubuntu
 https://www.how2shout.com/linux/installing-apache-spark-on-ubuntu-20-04-or-18-04/
 installing: https://computingforgeeks.com/how-to-install-apache-spark-on-ubuntu-debian/