Python | Maketrans () and translate () Functions

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maketrans ()

The maketrans () function is used to build a transition table, i.e. specifies a list of characters to be replaced in the entire string, or characters to be removed from the string

Syntax: maketrans (str1, str2, str3)

Parameters:
str1: Specifies the list of characters that need to be replaced.
str2: Specifies the list of characters with which the characters need to be replaced.
str3: Specifies the list of characters that needs to be deleted.

Returns: Returns the translation table which specifies the conversions that can be used by translate ()

Translate with maketrans ()

For translating characters in a string, translate () is used to perform translations. This function uses the translation transform specified with maketrans ().

Syntax: translate (table, delstr)

Parameters:
table: Translate mapping specified to perform translations.
delstr: The delete string can be specified as optional argument is not mentioned in table.

Returns: Returns the argument string after performing the translations using the translation table.

Code no. 1: code for translation using translate () and maketrans ().

# Python3 demo code
# translations using
# maketrans () and translate ()


# uk Set for character translation

str1 = " wy "


# specify to replace with

str2 = "gf"


# remove characters

str3 = "u"


# target string

trg = "weeksyourweeks"


# using maketrans () for
# build translation
# table

tab le = trg.maketrans (str1, str2, str3)


# Print original line

print ( "The string before translating is:" , end = "")

print (trg)


# using translate () to translate.

print ( "The string after translating is: " , end = " ")

print (trg.translate (table))

Output:

 The string before translating is: weeksyourweeks The string after translating is: pythonengineering 

Translate without layouttrans ()

Translation can also be achieved by specifying the translation dictionary and passing as an object that acts as a display. In this case, there is no need for maketrans () to perform translations.

Code # 2: code for translation without layouttrans ().

# Python3 demo code
# no translations
# maketrans ( )


# display specification
# using ASCII

table = { 119 : 103 , 121 : 102 , 117 : None }


# target string

trg = "weeksyourweeks"


# Print original line

print ( "The string before translating is:" , end = " ")

print (trg)


# using translate () to translate.

print ( "The string after translating is:" , end = " ")

print (trg.translate (table))

Output:

 The string before translating is: weeksyourweeks The string after translating is: pythonengineering 

Application:
In many cases, errors can occur during coding or development, these functions provide simple and a quick way to replace and fix them and can potentially save you a lot of time.

👻 Read also: what is the best laptop for engineering students?

Python | Maketrans () and translate () Functions __del__: Questions

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

Python | Maketrans () and translate () Functions __del__: Questions

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:

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))

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]

We hope this article has helped you to resolve the problem. Apart from Python | Maketrans () and translate () Functions, check other __del__-related topics.

Want to excel in Python? See our review of the best Python online courses 2022. If you are interested in Data Science, check also how to learn programming in R.

By the way, this material is also available in other languages:



Ken Robinson

Moscow | 2022-12-08

I was preparing for my coding interview, thanks for clarifying this - Python | Maketrans () and translate () Functions in Python is not the simplest one. Checked yesterday, it works!

Boris Zelotti

Moscow | 2022-12-08

I was preparing for my coding interview, thanks for clarifying this - Python | Maketrans () and translate () Functions in Python is not the simplest one. I am just not quite sure it is the best method

Anna Gonzalez

London | 2022-12-08

I was preparing for my coding interview, thanks for clarifying this - Python | Maketrans () and translate () Functions in Python is not the simplest one. Will use it in my bachelor thesis

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