Counting in groups

In previous exercises, you pulled data from tables, then summarized the resulting data frames in pandas to create graphs. By using COUNT and GROUP BY in a SQL query, we can pull those summary figures from the database directly.

The hpd311calls table has a column, complaint_type, that categorizes call records by issue, such as heating or plumbing. In order to graph call volumes by issue, you'll write a SQL query that COUNTs records by complaint type.

pandas has been imported as pd, and the database engine for data.db has been created as engine.

Create a SQL query that gets the complaint_type column and counts of all records from hpd311calls, grouped by complaint_type.
Create a data frame with read_sql() of call counts by issue, calls_by_issue.
Run the last section of code to graph the number of calls for each housing issue.

Exercise

Counting in groups

Instructions