Python Business Intelligence Cookbook

Generating a frequency table of two variables

Creating a frequency table for a single column is good; creating a frequency table for two is even better. That's what we'll do in this recipe.

Getting ready

As with the previous recipes where we retrieve data from MongoDB, you need to have MongoDB running and to have imported the accidents dataset.

How to do it…

1. To generate a frequency table for two variables, begin by import the required libraries as follows:

   import pandas as pd
   import numpy as np
   from pymongo import MongoClient

2. Next, connect to MongoDB and run a query specifying the five fields to be retrieved from the MongoDB data:

   client = MongoClient('localhost', 27017) db = client.pythonbicookbook collection = db.accidents fields = {'Date':1, 'Police_Force':1, ...