Variables can be assigned to hold numerical values using syntax of the form
a = 5.2 * sqrt(64)
which may optionally be written in longhand as
let a = 5.2 * sqrt(64)
Variables can subsequently be used by name in mathematical expressions, for example:
print a / sqrt(64)
Having been defined, variables can later be undefined – set to have no value – using syntax of the form:
a =
Variables can also hold non-numeric data, such as strings, colors, dates, lists and dictionaries. The syntax for defining many of these data structures is similar to that used by python, for example:
myList = [8,2,1,7] myDict = {'john':27 , 'fred':14 , 'lisa':myList} myDate = time.fromCalendar(2012,7,1,14,30,0)
More information about Pyxplot’s data types can be found in Chapter 6.
A list of all of the variables which are currently defined can be obtained by typing show variables. Some constants are pre-defined by Pyxplot, and so a number of variables are listed even if none have been set by the user.