Python Variables in GRC

This tutorial describes how Python data types are used in GRC and how the variables are displayed.

The previous tutorial, Your First Flowgraph, shows how to build your first simple flowgraph. The next tutorial, Variables in Flowgraphs, describes how to use and modify variables in a more sophisticated flowgraph.

Introduction to Basic Python Data Types

GNU Radio Companion (GRC) uses Python data types to represent variables. The simplest data type are numbers. Numbers in Python can be floating point or integers:

floatNumber = 3.14
integerNumber = 2

Integers can be converted to floating point by casting using float(), and floating point numbers can be converted to integers using int():

floatNumber = float(2)
integerNumber = int(3.14)

Python uses both single quotes ' and double quotes " to contain strings:

singleQuoteString = 'string1'

doubleQuoteString = "string2"

• reference filter section that uses tuples to hold filter weights
• lists
• arrays

Using Python Types in GRC

• python data types accepted in variables

How GRC Displays Variable Values

• 32,000 -> 32k
• 0.25 -> 250m

The next tutorial, Variables in Flowgraphs, describes how to use and modify variables in a more sophisticated flowgraph.