In this article, we are going to discuss how to view all defined variables in Python. Viewing all defined variables plays a major role while debugging the code.
Method 1: Using dir() function
dir() is a built-in function to store all the variables inside a program along with the built-in variable functions and methods. It creates a list of all declared and built-in variables. There are two different ways to view all defined variables using dir( ). They are discussed below.
When no user-defined variable starts with ‘__’ :
- Define some variables of various types that are not starting with ‘__’
- Call dir and store it in a variable. It stores all the variable names defined before in the form of a list and stores the variable names as a string.
- Iterate over the whole list where dir( ) is stored.
- Print the item if it doesn’t start with ‘__’
Example:
Python3
# Define some variables of various types# that are not starting with '__'var2 = "Welcome to neveropen"var3 = {"1": "a", "2": "b"}var4 = 25var5 = [1, 2, 3, 4, 5]var6 = (58, 59) # call dir and store it in a variable.# It stores all the variable names defined# before in the form of a list# and stores the variable names as a string.all_variables = dir() # Iterate over the whole list where dir( )# is stored.for name in all_variables: # Print the item if it doesn't start with '__' if not name.startswith('__'): myvalue = eval(name) print(name, "is", type(myvalue), "and is equal to ", myvalue) |
Output:
var2 is <class ‘str’> and is equal to Welcome to neveropen
var3 is <class ‘dict’> and is equal to {‘1’: ‘a’, ‘2’: ‘b’}
var4 is <class ‘int’> and is equal to 25
var5 is <class ‘list’> and is equal to [1, 2, 3, 4, 5]
var6 is <class ‘tuple’> and is equal to (58, 59)
Storing the built-in variables and ignoring them
- Create a new variable and store all built-in functions within it using dir( ).
- Define some variables of various types.
- Again call dir and store it in a list subtracting the built-in variables stored previously.
- Iterate over the whole list.
- Print the desired items
Example:
Python3
# Create a new variable and store all# built-in functions within it using dir( ).not_my_data = set(dir()) # Define some variables of various types.var2 = "Welcome to neveropen"var3 = {"1": "a", "2": "b"}var4 = 25var5 = [1, 2, 3, 4, 5]var6 = (58, 59) # Again call dir and store it in a list # subtracting the built-in variables stored# previously.my_data = set(dir()) - not_my_data # Iterate over the whole list is stored.for name in my_data: # Exclude the un-necessary variable named not_my_data if name != "not_my_data": val = eval(name) print(name, "is", type(val), "and is equal to ", val) |
Output:
var2 is <class ‘str’> and is equal to Welcome to neveropen
var3 is <class ‘dict’> and is equal to {‘1’: ‘a’, ‘2’: ‘b’}
var6 is <class ‘tuple’> and is equal to (58, 59)
var4 is <class ‘int’> and is equal to 25
var5 is <class ‘list’> and is equal to [1, 2, 3, 4, 5]
Method 2: To print local and global variables
Locals() is a built-in function that returns a list of all local variables in that particular scope. And globals() does the same with the global variables.
Approach
- Create a list of all global variables using globals( ) function, to store the built-in global variables.
- Declare some global variables
- Declare a function.
- Declare some local variables inside it.
- Store all the local variables in a list, using locals keyword.
- Iterate over the list and print the local variables.
- Store the global variables in a list using globals keyword and subtract the previously created list of built-in global variables from it.
- Print them.
- Call the function.
Example:
Python3
# Create a list of all global variables using# globals( ) function, To store the built-in# global variables.not_my_data = set(globals()) # Declare some global variablesfoo5 = "hii"foo6 = 7 # Declare a function.def func(): # Declare some local variables inside it. var2 = "Welcome to neveropen" var3 = {"1": "a", "2": "b"} var4 = 25 var5 = [1, 2, 3, 4, 5] var6 = (58, 59) # Store all the local variables in a list, # using locals keyword. locals_stored = set(locals()) # Iterate over the list and print the local # variables. print("Printing Local Variables") for name in locals_stored: val = eval(name) print(name, "is", type(val), "and is equal to ", val) # Store the global variables in a list using # globals keyword and subtract the previously # created list of built-in global variables from it. globals_stored = set(globals())-not_my_data # Print the global variables print("\nPrinting Global Variables") for name in globals_stored: # Excluding func and not_my_data as they are # also considered as a global variable if name != "not_my_data" and name != "func": val = eval(name) print(name, "is", type(val), "and is equal to ", val) # Call the function.func() |
Output:
Printing Local Variables
var2 is <class ‘str’> and is equal to Welcome to neveropen
var6 is <class ‘tuple’> and is equal to (58, 59)
var4 is <class ‘int’> and is equal to 25
var5 is <class ‘list’> and is equal to [1, 2, 3, 4, 5]
var3 is <class ‘dict’> and is equal to {‘1’: ‘a’, ‘2’: ‘b’}
Printing Global Variables
foo6 is <class ‘int’> and is equal to 7
foo5 is <class ‘str’> and is equal to hii
