Exercise

Working with OrderedDictionaries

Recently in Python 3.6, dictionaries were made to maintain the order in which the keys were inserted; however, in all versions prior to that you need to use an OrderedDict to maintain insertion order.

Let's create a dictionary of all the stop times by route and rider, then use it to find the ridership throughout the day.

Instructions

100 XP

Import OrderedDict from collections.
Create an OrderedDict called ridership_date.
Iterate over the list entries, unpacking it into date and riders.
If a key does not exist in ridership_date for the date, set it equal to 0 (if only you could use defaultdict here!)
Add riders to the date key of ridership_date.
Print the first 31 records. Remember to convert the items into a list.