Calculate the average number of groups (residues) for protein chains.
from pyspark.sql import SparkSession
from mmtfPyspark.io import mmtfReader
from mmtfPyspark.filters import ContainsLProteinChain
from mmtfPyspark.mappers import StructureToPolymerChains
spark = SparkSession.builder.appName("Solution-2").getOrCreate()
path = "../resources/mmtf_reduced_sample/"
pdb = mmtfReader.read_sequence_file(path)
prot_chains = ... your code here ...
total_groups = ... your code here ...
... your code here ...
197.10918825374506
spark.stop()