List items to int python

Convert List to Integer in Python

To convert the entire list into one integer in Python:

• Create a list having integer-type elements.
• Declare and initialize a variable with 0 ; it will be used to hold the final integer value.
• Use the for loop to iterate over the list items.
• In each iteration:
  • multiply the variable created in the second step with 10 and add the current list item.
  • Assign the value (produced in the previous step) to the variable created in step two.

  First, we created a list named my_list with three elements of integer type. Then, our job is to convert that from a list of integers to one integer value; for that, we defined and initialized the variable named number with 0 . Then, we used the for loop to go through all the list items.

  For every current_digit in the my_list , we multiplied the number with 10 and added current_digit . This will have the effect of shifting digits of the number variable to the left by one place and adding the upcoming digit to the right. For instance, we have a [5, 6, 7] list in the above example, which will have the following iterations:

  Once the loop is over, we will have 567 as one integer type value; to check its type, you can use the type() method as type(number) .

  Using List Comprehension

  To convert the entire list into one integer in Python:

  • Create a list having integer-type elements.
  • Use list comprehension to convert each list item from integer type value to string type value; for instance, from [5, 6, 7] to [‘5’, ‘6’, ‘7’] .
  • Use the join() method to join all the list items to make a single string value, such as from [‘5’, ‘6’, ‘7’] to ‘567’ .
  • Use the int() method for changing data type from string to integer.

  After creating a list named my_list having integer type elements, we used list comprehension to loop over all the list items and converted every item to a string by wrapping around with the str() method. The str() method converts the specified value to a string type value. At this point, we had my_list as [‘5’, ‘6’, ‘7’] , which we stored in the new_list variable.

  Next, we used the join() method to join all the elements of new_list to make it one string value and stored it in the string_value variable. Using the join() method, we transformed [‘5’, ‘6’, ‘7’] to ‘567’ .

  Now, we can use the int() method to dynamically cast string_value to an integer value which we saved in number . Finally, we used the print() method to print the value of the number variable; we can also print the type of number by printing as print(type(number)) .

  Further reading:

  Convert List to String in Python

  Convert List to Matrix in Python

  Using map() and join() Methods

  To convert the entire list into one integer in Python:

  • Create a list having integer-type elements.
  • Use the map() method to convert every list item’s type from integer to string.
  • Use the join() method to join all the list items to make it one string-type value.
  • Use the int() method to cast the type from string to integer dynamically.

  This code fence is similar to the previous example, but we used functions instead of list comprehension. Here, we used the map() method to transform [5, 6, 7] to [‘5’, ‘6’, ‘7’] and saved it in new_list variable. If you are curious how the map() function works, then let’s understand that below.

  We passed two arguments to map() ; the first was the function ( str ), and the second was the iterable ( my_list ). The map() method iterated over the my_list items where every list item was passed to the str function as an argument; for instance, the first list item 5 was sent to the str function as str(5) , which returned string type value as ‘5’ . By using the map() method, we transformed the [5, 6, 7] to [‘5’, ‘6’, ‘7’] , which we saved in the new_list variable.

  This new_list variable was then passed to the join() method to join all the list items and form one string type value as ‘567’ that we stored in string_value . Finally, we performed typecasting using the int() method. This int() method took string_value as a parameter and converted its type from string to integer that we saved in the number variable.

  Using the reduce() Method with lambda Expression

  To convert the entire list into one integer in Python:

  • Create a list having integer-type elements.
  • Use the reduce() method with the lambda function to convert the entire list to one integer.

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  Convert list to int Python | Example code

  Use the int() function to Convert the list to int in Python. This method with a list comprehension returns one integer value that combines all elements of the list.

  Example convert list to int Python

  Simple example code converting [1, 2, 3] into one integer in 123. Use list comprehension to construct a new list with str(int) applied to all elements.

  l = [1, 2, 3] s = [str(integer) for integer in l] a_string = "".join(s) res = int(a_string) print(res) print(type(res))

  

  How to convert all elements of a list to int in Python

  l = [1, 2, 3] res = [int(item) for item in l] print(l) print(type(l))

  Using the map function:

  str_list = ['1', '2', '3', '4'] int_list = list(map(int, str_list)) print(int_list) # Output: [1, 2, 3, 4] 

  Comment if you have any doubts or suggestions on this Python list to int program.

  Note: IDE: PyCharm 2021.3.3 (Community Edition)

  Windows 10

  Python 3.10.1

  All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.

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  How to Convert List of Strings to Ints in python : 4 Methods

  

  Do you want to Convert List of Strings to Ints in python? If yes then you have come to the right place. In this entire post, you will know the various methods to convert the list of strings to int in python.

  Methods to Convert List of Strings to Ints in python

  Before going to the methods let’s create a sample list of strings. The list contains all the numerical values, but of string type. Let’s create them.

  

  You can see in the above figure all the numerical values are in a single quote. It clearly represents that all these are strings.

  Method 1: Convert String Array to Int array using python map

  In this method, I will use the Python map() function to achieve the results. Just pass your string array and typecast the results to the list(). And you will get the list of int.

  Execute the following code.

  

  Output

  Method 2: Convert List of strings to ints using list comprehension in python

  The second method to convert string to int is using the list comprehension in python. Inside the list comprehension, there will be a loop that converts a string to int.

  Execute the following code.

  

  Method 3: Convert List of strings to ints using a new list

  You can also convert list of strings to ints by using the new or fresh list. After that, you have to append all the converted strings to that list. And if you print the new list, you will get all the values as int.

  You can see in the above code in each iteration of the loop, the value is typecasting to int and appending to the int_list.

  

  Output

  Method 4: Convert strings to ints in python using NumPy array

  In this method, I will use the NumPy python module for conversion. First I will convert the strings list to NumPy array. And then change the type of the array to int using the astype(“int”). Lastly, convert it again to the list.

  Execute the following lines of code.

  

  Output

  Conclusion

  These are the methods to Convert List of Strings to Ints in python. All methods are great and it depends on your usage. Hope We have solved your queries you are searching for. Even if you have any queries then you can contact us for more information. We are always ready to help you.

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  Python Convert List of Strings to Ints

  

  Python allows to work with various types of data such as “int”, “float”, etc., and the conversion of one data type into others i.e., “Typecasting” is a common task in Python. For instance, you may need to convert a list of strings to ints when there is a need to perform arithmetic operations on them or use them as indices.

  This blog write-up will explore the ways to convert a strings list to ints in Python utilizing several examples.

  How to Convert/Transform List of Strings to Integers in Python?

  The below methods are utilized in Python to convert/transform a list of strings into an integers list:

  Method 1: Convert List of Strings to Integers Utilizing the “for” Loop

  The “for” loop can be utilized with the “int()” function to convert the string list into an integers list.

  Example

  Overview of the below code:

  list_of_strings = [ ’45’ , ’55’ , ’70’ ]
  for i in range ( 0 , len ( list_of_strings ) ) :
  list_of_strings [ i ] = int ( list_of_strings [ i ] )
  print ( list_of_strings )

  • The list of strings is initialized.
  • The “for” loop iterates over the “range()” function starting from “0” and stops at the end of the strings list.
  • Inside the “for” loop, each “string” value is converted into an “int” using the “int()” function.

  Output

  

  The input list of strings has been converted into a list of integers appropriately.

  Method 2: Convert List of Strings to Integers Using “List Comprehension”

  “List Comprehension” is a special way to create/construct a new list from the existing/current element of the list.

  Syntax

  Example

  This code example shows the conversion of a strings list into a list of integers:

  list_of_strings = [ ’45’ , ’55’ , ’70’ ]
  print ( ‘Given List of Strings: ‘ , list_of_strings )
  print ( ‘ \n List of Ints: ‘ , [ int ( i ) for i in list_of_strings ] )

  According to the above code, in the applied “List Comprehension” approach, the “for” loop iterates through the list of strings, and the “int()” function converts each element of the string list into integers.

  Output

  

  As seen, an integer list has been generated from the string input list.

  Method 3: Convert List of Strings to Integers Using the “eval()” Function

  In Python, the “eval()” function evaluates arbitrary Python expressions based on string or compiled code inputs. This function can be utilized with the “for” loop to convert the strings list to an integers list.

  Syntax

  In the above syntax, the “expression” parameter specifies the expression that needs to be evaluated, and the optional parameters “globals” and “locals” specify the global and local variables for the evaluation context, respectively.

  Example

  The below code block transforms a list of strings to an integers list:

  list_of_strings = [ ’45’ , ’55’ , ‘-99′ , ’70’ ]
  print ( ‘Given List of Strings: ‘ , list_of_strings )
  print ( ‘ \n List of Ints: ‘ , [ eval ( i ) for i in list_of_strings ] )

  • A list of strings is initialized.
  • The “eval()” function converts the element value of the strings list into integers by iterating through the list using the “for” loop.

  Output

  

  As seen, an integer list has been generated from the string input list.

  Method 4: Convert List of Strings to Integers Utilizing the “map()” Function

  The “map()” function processes and transforms all the items in an iterable without utilizing a traditional “for” loop, this practice is commonly referred to as “Mapping”. This function executes a specified function for each item in an iterable.

  Syntax

  In the above syntax, the “function” parameter specifies the function that is going to be applied to each item of the given iterable. The “iterable” parameter is iterable that we want to process.

  Example

  The following code transforms the strings list into an integers list:

  list_of_strings = [ ’45’ , ’55’ , ‘-99′ , ’70’ ]
  print ( ‘Given List of Strings: ‘ , list_of_strings )
  print ( ‘ \n List of Ints: ‘ , list ( map ( int , list_of_strings ) ) )

  In the above code lines, the “map()” function takes “int” as a first argument and applies this function to all the elements of the given list of strings. The “list()” function converts the map object into an integer list using the “list()” function.

  Output

  

  Conclusion

  To convert a list of strings to integers, various methods such as the “for” loop, “List Comprehension”, “eval()”, or the “map()” function is used in Python. These methods effectively convert string lists into lists of integers. This write-up delivered various approaches to convert/transform a list of strings to ints in Python using relevant examples.

  About the author

  Haroon Javed

  Hi, I’m Haroon. I am an electronics engineer and a technical content writer. I am a tech geek who loves to help people to the best of my knowledge.

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