Python del multiple variables
Python is an object-oriented programming language; therefore memory management is not a concern. There is no need for manual intervention because it features a "Python memory manager" that handles memory allocation and management. However, some particular situations need looking back in recollection.
Let's examine the most fundamental building block of memory—variables in Python—and examine how memory functions when dealing with them.
What in Python Is a Variable?
In general, a variable is a name given to the portion of memory where values are stored. The word "variable" itself denotes that several values may apply to the same area. The question of whether it applies to all programming languages must be on your mind. You'll be surprised to learn that everything in Python is an object. Classes, lists, tuples, and variables are a few examples.
References to the real objects that contain the provided value are made using variables. We don't need to declare variables or their data types before utilizing them in Python because of this.
For instance:
# Declaring variable without data type
var1 = 5
print(var1)
# type of variable 1
print(type(var1))
# using variable without prior declaration
for i in range(2):
print(i)
A variable has been defined and utilized without the need for data type declarations or initialization, as you can see.
Output:
5
<class 'int'>
0
1
Take note of the class 'int' that type(var1) returns. This suggests that variable var1 is a member of the integers class.
Sounds Perplexing? Don't worry; we'll look at how Python handles memory management when a variable is declared.
How does Python manage its memory?
When using Python, there are two different kinds of memory:
Fixed memory
Adaptive memory
Dynamic memory allocation is used by Python, thus memory allocation happens while the application is executing. The dynamic memory allocation is carried out using the heap data structure.
Static memory is kept in the stack data structure in addition to the heap data structure. Python makes a distinction between static and dynamic memory, so keep that in mind.
Here, the function call stack is referred to as static memory. Recall the function call sequence that was saved in recursion using the stack. Unlike other programming languages, Python does not need explicit memory management.
Python features a Python manager that controls the application data in memory, necessitating little human involvement in memory management.
What happens when a variable is declared in Python?
In Python, variables can be references to both constants and values as well as objects. When a variable is defined in Python, it creates an object in the Private Heap Space that contains the value of the variable. As a reference to the stated item, the variable is generated in the stack memory.
Not easily understood? Let's examine a case in point. Consider the variable 'a,' which has the value 5 if you need to declare one. See what happens behind the scenes by taking a look at the picture below!
In Python, define a variable
As you can see, a variable or reference to the object that contains the value (5) is generated in stack memory, but the object itself is created in the private heap space. Consider creating a second variable, b, that has the same value as a. Can you currently forecast how the RAM will be distributed?
Given that the value is the same, Python's memory management system will establish a second reference, "b," to the same object (which contains 5) that is referred to by "a."
There will be two pointers to the same item as a consequence. Any modification to either reference will destroy the reference link to that object (storing 5) and, in some cases, the creation of a new object.
Variables in Python may be viewed as pointers to the objects, much like in C and C++.
Why are variables need to be deleted?
Memory management is one of the most crucial factors to take into account while working with Python or any other programming language. You might be wondering why memory management has become so important. Even the consequences are hidden from you.
Let me tell you that this is because you haven't used big data, which is powerful software that analyzes a lot of data. While dealing with enormous amounts of data, you'll observe how this memory management affects the overall efficacy and processing speed of your software.
Data structures were developed for this reason!
One of the most important considerations while coding in Python or other programming languages is memory management. Most likely, you're asking why memory management is so crucial. You're not even aware of how
While dealing with enormous amounts of data, you'll observe how this memory management impacts the overall efficacy and processing speed of your software.
So, how does Python's delete() function operate? As was previously mentioned, Python features a memory manager that is in charge of allocating or allocating the memory heap. The objects and other data structures utilized by the application are stored in Python's memory heap.
As a result, when a variable—a reference to an object—is no longer in use, the Python language recognizes this.
What happens when a variable is deleted?
As previously mentioned, Python contains a Python memory manager that is in charge of allocating or allocating the memory heap. The objects and other data structures utilized by the application are stored in Python's memory heap.
As a consequence, when a variable (a reference to an object) is no longer in use, Python memory management frees up space by eliminating any unnecessary objects. Getting rid of things that are no longer needed is what is meant by garbage pickup.
Garbage collector
The garbage collector for your Python application is a background process. The trash collector also begins as soon as you run the Python application in the background. Consequently, a waste collector doesn't have to be started or requested expressly. This routinely occurring procedure frees up memory space from things that the software is no longer using.
How will the garbage collector decide whether to destroy a variable (object)? Well, it's rather easy. Since everything in Python is an object, each object needs references. An item may have more than one reference, as previously mentioned. A variable's object is immediately generated in the Private Heap Space when you create it.
Let's go back to the preceding instance. since the object (storing 5) has two references, "a" and "b." Assume that variable a requires removal at this time. What do you think would occur in the memory?
How to delete a variable
Because the object contains a reference (the variable "b") pointing to it, it won't be removed by itself. However, the reference (variable 'a') has been deleted.
An object's reference count is kept in a database. In Python, this is referred to as reference counting.
In the aforementioned example, our object (containing 5) had two references, which were variables 'a' and 'b'. Consequently, our object (which stores 5) will have a reference count of 2. This object won't be discarded by the garbage collector until its Reference Count is zero. This indicates that the object (containing 5) won't be erased until both the variables ('a' and 'b') are removed.
However, this traditional method fails when dealing with reference cycles. Let's now examine how to get rid of these variables in Python.
How Can Python Variables Be Removed?
We've already spoken about Python's memory allocation and de-allocation processes. There are some situations when you need to force memory cleaning, even though Python contains a garbage collector and memory manager to manage memory space automatically.
while designing memory-intensive software or working with large amounts of data, for instance. There aren't many methods for deleting variables in Python. Here are a few of the popular techniques:
1) Employing the term del
The most popular and straightforward way to remove variables in Python is to use the 'del' command. The items are deleted via the del keyword. Because everything in Python is an object, you can also remove lists, tuples, and dictionaries by using the 'del' command. Its syntax is straightforward.
# Example -> Deleting a variable in Python using the 'del' keyword
# declaring variable
a = 25
print("variable: ", a)
# deleting the variable
del a
# calling out the variable again
print("variable: ", a)
How will you know whether the variable has been removed must be on your mind. After removing the variable, try calling it once more.
Output:
variable: 25
Traceback (most recent call last):
File ".\temp.py", line 10, in
print("variable: ", a)
name 'a' not defined: NameError
Note that the variable "a" was called after being removed and a NameError exception was thrown. This demonstrates that the del keyword was used to remove the variable "a."
When deleting variables in Python with the del keyword, you must be certain that you won't need to access the variable again at any point in the future. Errors may result from the needless deletion of variables (or objects).
You won't be able to access these variables once they have been deleted from the program.
2) Python: Multiple Variables Can Be Removed
Using Python's del keyword, you may also remove many variables at once. It resembles initializing several variables in a line, each separated by a comma.
Defined in the syntax del variableName1, variableName2, and variableName3.
Example:
# Example -> Deleting multiple variables in Python
# Declaring multiple variables
a, b, c = 5, 10, 15
print("variables: a: ", a, " b: ", b, " c: ", c)
# deleting multiple variables
del a, b, c
# calling out the variable again
print("variables: a: ", a, " b: ", b, " c: ", c)
Deleting multiple variables is similar to deleting a variable in Python.
Output:
Variables: a: 5 b: 10 c: 15
Traceback (most recent call last):
File ".\temp.py", line 10, in
print ("variables: a: ", a, " b: ", b, " c: ", c)
NameError: name 'a' is not defined
Keep in mind that the NameError message only mentioned the variable "a." Line-by-line interpretation is used since Python is an interpreted language. Variable 'a' is the first undeclared variable to be found, hence the execution process stops at the first error. Therefore, just the variable "a" is highlighted by the NameError warning.
3) Using globals() and dir()
Additionally, you may instantly erase "All variables" in your application. I refer to "All Variables" as the user-defined variables in your program's local or global scope.
As you are aware, the dir() function retrieves all of an object's properties and methods. Even if no object is named, it nevertheless provides a list of all the variables and built-in methods used in your application.
For instance:
# Declaring multiple variables
a, b, c = 5, 10, 15
print("variables: a: ", a, " b: ", b, " c: ", c)
#inititalizing d with dir()
d = dir()
#printing the directory
print(d)
You'll notice that print(d) prints out the list of all the variables and methods in the given program.
Output:
Variables: a: 5 b: 10 c: 15
['__annotations__', '__builtins__', '__cached__', '__doc__',
'__file__', '__loader__', '__name__', '__package__', '__spec__',
'a', 'b', 'c']
'a', 'b', and 'c' are our user-defined variables, and they are listed last double underscores (__) are used as a prefix and suffixes to separate built-in variables from user-defined variables.
In addition, the global() function produces a dictionary that contains a list of all the program's global variables and symbols, together with a list of their values. For instance –
# Declaring multiple variables
a, b, c = 5, 10, 15
print("variables: a: ", a, " b: ", b, " c: ", c)
# inititalizing g with globals()
g = globals()
print(g)
You'll notice the difference between the dir() and globals() methods with the following output:
variables: a: 5 b: 10 c: 15
{'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x00000254F32FEB08>, '__spec__': None,
'__annotations__': {}, '__builtins__': , '__file__': '.\\temp.py', '__cached__': None,
'a': 5, 'b': 10, 'c': 15, 'g': {...}}
Note that the values of the declared variables are written after the dictionary.
Let's start by getting rid of these user-defined variables. To distinguish between user-defined and built-in variables, you must determine whether the variable name contains any double underscores ('__').
Example: print "variables: a: ", a, " b: ", b, " c: ", c" print("variables: ", a, " c: ", c") to delete all variables in Python.
Initializing d with dir() will result in the storage of a list of all the variables used in the program.
#You must look for user-defined variables in the obj in the d directory.
If obj. starts with ('__') is not used, check for built-in variables and functions.
#deleting the aforementioned object since the del global() user-defined method[obj]
# re-calling the variables
print("variables: a:,","b:,","c:,"a:,"b:,"c:")
Note the syntax used to remove variables. First, by searching for ('__') in the prefix, we must establish if the variable (object) is user-defined or not. The object must be taken out of the globals (if it is user-defined). Because it is a dictionary, we may provide the object to globals() for deletion.
Output:
Variables: a: 5 b: 10 c: 15
Traceback (most recent call last):
File ".\temp.py", line 17, in
print("variables: a: ", a, " b: ", b, " c: ", c)
NameError: name 'a' is not defined
And Voila!! There are no longer any user-defined variables. At once!
When it comes to a program or piece of software's computational effectiveness, memory management is a crucial component.
Even though Python has its own memory manager and garbage collector, we may still start one or remove variables to free up memory. In Python, you can get rid of objects by using the 'del' keyword. Variables, lists, tuples, sets, dictionaries, and much everything else in Python are all considered objects. Try using the aforementioned techniques to eliminate the other items. Each time, the outcome will take you by surprise.