Python Business Intelligence Cookbook

Generating a frequency table for a single column by date

A frequency table is another way of summarizing data; it shows the number of times a value occurs. In this recipe, we will create a frequency table of casualties by date.

Getting ready

To use this recipe, you need to have MongoDB running, and to have the accidents data imported.

How to do it…

1. To generate a frequency table for a single column by date, begin by importing the Python libraries that we need:

   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, ...