Introduction

python name error name sys is not defined is an error that can occur when you are trying to use the ipython interpreter. This error means that the python interpreter cannot find the sys module, which is a built-in python module. There are a few ways to fix this problem.

What is Python?

Python is an interpreted, high-level, general-purpose programming language. Created by Guido van Rossum and first released in 1991, Python has a design philosophy emphasising code readability, notably using significant whitespace. It provides constructs that enable clear programming on both small and large scales. In July 2018, Van Rossum stepped down as the leader in the language community after 30 years.

What is iPython?

iPython is a powerful interactive shell that features easy editing and recording of your work, as well as dynamic generation of plots and other graphics. You can use iPython for data analysis, scientific computing, and even simple scripting.

What is a name error?

In Python, a NameError is raised when a local or global variable (or object) is referenced before it has been assigned a value.

In other words, you’re trying to use a variable before it has been created. This can happen in a number of ways:

-You might have misspelled the name of the variable. For example:

print(x) # raises NameError: name 'x' is not defined

-You might be trying to access a global variable from within a function. In Python 3, all variables defined inside a function are local by default. For example:
“`python
def my_func():
print(x) # raises NameError: name ‘x’ is not defined

x = 5 # x is global

my_func() # works fine now!

 -You might be trying to access a local variable from outside the function. For example:

python
def my_func():
x = 5 # x is local

my_func()

print(x) # raises NameError! x only exists inside my_func()!
“`

What is sys?

sys is a module in Python that provides access to system-specific parameters and functions. It is a standard library module, which means that it is always available to your Python programs without having to install it.

How to fix a name error.

A nameerror can occur when you try to run a Python program that doesn’t have all the necessary modules installed. To fix this, you’ll need to install the missing module.

The best way to do this is to use a virtual environment (virtualenv). This will allow you to create a separate environment for your Python programs, which will include all the necessary modules.

To install virtualenv, run the following command:

pip install virtualenv

Once virtualenv is installed, you can create a new environment by running the following command:

virtualenv ENVNAME

Replace ENVNAME with the name of your new environment. This will create a new directory called ENVNAME that contains your new environment.

To activate your new environment, run the following command:

source ENVNAME/bin/activate