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Python.Engineering Wiki Remove Key From Javascript Object

Remove Key From Javascript Object

__del__ | __delete__ | __dict__ | dictionary contains | iat | JavaScript | mean | sin
Michael Zippo Michael Zippo 04.11.2021
Python’s

pop () method and remove del keyword keys from a dictionary. pop () takes as argument the name of the key you want to remove from the dictionary. The keyword is independent del and refers to a specific key.

Dictionaries are mutable objects. This means that it is possible to modify the dictionary of values. Therefore, you can delete dictionary keys at any time if they are no longer needed.

Suppose you have a Python dictionary that stores information about books sold in a bookstore. You may decide to remove a key that indicates whether the book was in the manager’s recommended list.

Python Remove the key from the dictionary

To remove a key from a Python dictionary, use the pop () method or word - key in "del" method . Both methods work the same in that they remove keys from a dictionary. The pop () method accepts a key name as an argument any "del" accepts a dictionary item after the word del.

In this guide, we discuss how to remove a key from a Python dictionary. We’ll see two examples so you can quickly start removing dictionary keys

Remove key from a Python dictionary:. Pop () Method

pop Python () removes an item from a dictionary.

This method can also be used to remove items from a list at a certain index value. For this guide, we will focus on removing an item from a dictionary. Read our tutorial on Python pop list () Guide for more information on how to remove an item from a list.

The syntax of this method:

The pop () method can accept two parameters:

  • the name of the key you want to remove (required ).
  • the value that should be returned if a key cannot be found ( optional).

by default, pop () returns the value associated with the key removed from a dictionary .

If you specify only one parameter, the interpreter can throw a Python KeyError . This happens if you try to delete an item in a dictionary that does not exist.

example pop ()

We are creating a program that tracks shoes that are in stock at a local shoe store. Let start by defining a Python array . This table contains a list of shoes that we can work with:

Our shoe list contains three dictionaries. Each dictionary contains four keys: id, name, brand and IN_STOCK. id is a unique identifier for a shoe. name is the name of a shoe. brand is the brand that produces a shoe. in_stock indicates whether a shoe is in stock.

The shoe store has decided to remove the key tag "in_stock" . They want to replace the key with a new value that tracks how many pairs of each shoe are available. To remove the "in_stock" key element from our dictionaries, we will use the pop () method:

the first embedded parameter - in function pop () it is the name of the key we want to remove. Our code returns the second value if the specified key does not exist. By default, the pop () returns the name of the removed key.

In each iteration of our loop, we check if the "in_stock" method the key was removed using a " Python if statement . If "remove_key" has a value other than None, it means our key has been removed.

After a worm deleted the "in_stock" element type our dictionaries, our code prints our new dictionary to the console. Run our code and see what happens:

remove "available" at all of our shoes. Our code shows us that our keys have been removed and prints our updated dictionary to the console

Remove key from a Python dictionary:. Del

The Python del declaration deletes an object. Because the key value pairs in the dictionaries are objects, you can remove them in using the "del" word - key button .

"del" word - key is used to delete an existing key. Throws a KeyError if a key is missing in a dictionary

Let’s examine the syntax of this keyword:.

we use the notation index to retrieve the item from the dictionary that we want to delete. "Key" represents the name of the key whose key value pair we want to remove from the dictionary.

Example

We are going to build a program that removes a key from an individual dictionary. This dictionary contains detailed information about a particular shoe:

The shoe store decided not to discount Jordan shoes. They want to remove the "discount" key from the dictionary. We can do this using the del keyword: print

This code removes the "reduction" key from our list and shows us the new dictionary:

The "reduction" key is no longer in our dictionary

Python pop () vs del

There are two differences between pop () and del.

First, the pop () method returns the value the key is removed from a dictionary, while del returns no value.

Second , the keyword returns a KeyError del if a key is not in a dictionary. on the other hand, the pop () method returns a KeyError only if you don’t specify a second parameter. The second parameter is the default to return if a key is not in a dictionary.

Conclusion

Both pop () method and the del keyword allow you to remove keys from a dictionary. em> is generally more useful because it is able to return a default value if a key is not deleted. This is useful because it helps prevent KeyErrors.

Want to learn more about coding in Python? Re publishes on how to learn Python . This guide contains a list of the best online courses and learning resources you can use to build your Python knowledge.

Remove Key From Javascript Object __del__: Questions

__del__

How can I make a time delay in Python?

5 answers

I would like to know how to put a time delay in a Python script.

2973

Answer #1

import time
time.sleep(5)   # Delays for 5 seconds. You can also use a float value.

Here is another example where something is run approximately once a minute:

import time
while True:
    print("This prints once a minute.")
    time.sleep(60) # Delay for 1 minute (60 seconds).

2973

Answer #2

You can use the sleep() function in the time module. It can take a float argument for sub-second resolution.

from time import sleep
sleep(0.1) # Time in seconds

__del__

How to delete a file or folder in Python?

5 answers

How do I delete a file or folder in Python?

2639

Answer #1

Path objects from the Python 3.4+ pathlib module also expose these instance methods:

Remove Key From Javascript Object __delete__: Questions

2639

Answer #2

Path objects from the Python 3.4+ pathlib module also expose these instance methods:

2639

Answer #3

Python syntax to delete a file

import os
os.remove("/tmp/<file_name>.txt")

Or

import os
os.unlink("/tmp/<file_name>.txt")

Or

pathlib Library for Python version >= 3.4

file_to_rem = pathlib.Path("/tmp/<file_name>.txt")
file_to_rem.unlink()

Path.unlink(missing_ok=False)

Unlink method used to remove the file or the symbolik link.

If missing_ok is false (the default), FileNotFoundError is raised if the path does not exist.
If missing_ok is true, FileNotFoundError exceptions will be ignored (same behavior as the POSIX rm -f command).
Changed in version 3.8: The missing_ok parameter was added.

Best practice

  1. First, check whether the file or folder exists or not then only delete that file. This can be achieved in two ways :
    a. os.path.isfile("/path/to/file")
    b. Use exception handling.

EXAMPLE for os.path.isfile

#!/usr/bin/python
import os
myfile="/tmp/foo.txt"

## If file exists, delete it ##
if os.path.isfile(myfile):
    os.remove(myfile)
else:    ## Show an error ##
    print("Error: %s file not found" % myfile)

Exception Handling

#!/usr/bin/python
import os

## Get input ##
myfile= raw_input("Enter file name to delete: ")

## Try to delete the file ##
try:
    os.remove(myfile)
except OSError as e:  ## if failed, report it back to the user ##
    print ("Error: %s - %s." % (e.filename, e.strerror))

RESPECTIVE OUTPUT

Enter file name to delete : demo.txt
Error: demo.txt - No such file or directory.

Enter file name to delete : rrr.txt
Error: rrr.txt - Operation not permitted.

Enter file name to delete : foo.txt

Python syntax to delete a folder

shutil.rmtree()

Example for shutil.rmtree()

#!/usr/bin/python
import os
import sys
import shutil

# Get directory name
mydir= raw_input("Enter directory name: ")

## Try to remove tree; if failed show an error using try...except on screen
try:
    shutil.rmtree(mydir)
except OSError as e:
    print ("Error: %s - %s." % (e.filename, e.strerror))

__delete__

Is there a simple way to delete a list element by value?

5 answers

I want to remove a value from a list if it exists in the list (which it may not).

a = [1, 2, 3, 4]
b = a.index(6)

del a[b]
print(a)

The above case (in which it does not exist) shows the following error:

Traceback (most recent call last):
  File "D:zjm_codea.py", line 6, in <module>
    b = a.index(6)
ValueError: list.index(x): x not in list

So I have to do this:

a = [1, 2, 3, 4]

try:
    b = a.index(6)
    del a[b]
except:
    pass

print(a)

But is there not a simpler way to do this?

1055

Answer #1

To remove an element"s first occurrence in a list, simply use list.remove:

>>> a = ["a", "b", "c", "d"]
>>> a.remove("b")
>>> print(a)
["a", "c", "d"]

Mind that it does not remove all occurrences of your element. Use a list comprehension for that.

>>> a = [10, 20, 30, 40, 20, 30, 40, 20, 70, 20]
>>> a = [x for x in a if x != 20]
>>> print(a)
[10, 30, 40, 30, 40, 70]

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