Python is completely object oriented, and not "statically typed". You do not need to declare variables before using them, or declare their type. Every variable in Python is an object. Show
This tutorial will go over a few basic types of variables. NumbersPython supports two types of numbers - integers(whole numbers) and floating point numbers(decimals). (It also supports complex numbers, which will not be explained in this tutorial). To define an integer, use the following syntax:
To define a floating point number, you may use one of the following notations:
StringsStrings are defined either with a single quote or a double quotes.
The difference between the two is that using double quotes makes it easy to include apostrophes (whereas these would terminate the string if using single quotes)
There are additional variations on defining strings that make it easier to include things such as carriage returns, backslashes and Unicode characters. These are beyond the scope of this tutorial, but are covered in the Python documentation. Simple operators can be executed on numbers and strings:
Assignments can be done on more than one variable "simultaneously" on the same line like this
Mixing operators between numbers and strings is not supported:
ExerciseThe target of this exercise is to create a string, an integer, and a floating point number. The string should be named
Use variables to store values.
Use print to display values.
Variables must be created before they are used.
Variables can be used in calculations.
Use an index to get a single character from a string.
Use a slice to get a substring.
Use the built-in function len to find the length of a string.
Python is case-sensitive.
Use meaningful variable names.
What do you call a variable in Python?Officially, variable names in Python can be any length and can consist of uppercase and lowercase letters ( A-Z , a-z ), digits ( 0-9 ), and the underscore character ( _ ). An additional restriction is that, although a variable name can contain digits, the first character of a variable name cannot be a digit.
How do you run a variable in Python?If you want to execute Python statements, you can use exec(string). For example, >>> my_code = 'print "Hello World!"' >>> exec(my_code) Hello World!
How do you call variable names?To call a variable from a data set, you have two options:. You can call var1 by first specifying the name of the data set (e.g., mydata ): > mydata$var1 > mydata[,"var1"]. Alternatively, use the function attach() , which attaches the data set to the R search path. You can now refer to variables by name.. What is $_ in Python?According to Python doc, the special identifier _ is used in the interactive interpreter to store the result of the last evaluation. It is stored in the builtin module.
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