Convert list to number python

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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Convert list to number python

Last updated: Feb 20, 2023
Reading time · 5 min

# Table of Contents

# Convert a List of Floats to a List of Integers in Python

To convert a list of floats to a list of integers:

1. Use a list comprehension to iterate over the list.
2. Use the int() class to convert the current float to an integer.
3. The new list will only contain integer values.

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list_of_floats = [1.23, 3.45, 5.67] result = [int(item) for item in list_of_floats] print(result) # 👉️ [1, 3, 5] 

We used a list comprehension to iterate over the list of floats.

List comprehensions are used to perform some operation for every element, or select a subset of elements that meet a condition.

On each iteration, we pass the current float value to the int class to convert it to an integer.

The new list only contains integer values.

# Convert a List of Floats to a List of Integers using round()

You can also use the round() function to round each float to the nearest integer.

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list_of_floats = [1.23, 3.45, 5.67] result = [round(item) for item in list_of_floats] print(result) # 👉️ [1, 3, 6] 

Instead of converting to an integer by dropping the decimal, this example converts the floating-point numbers in the list by rounding them to the nearest integers.

The round function takes the following 2 parameters:

Name	Description
number	the number to round to ndigits precision after the decimal
ndigits	the number of digits after the decimal, the number should have after the operation (optional)

The round function returns the number rounded to ndigits precision after the decimal point.

If ndigits is omitted, the function returns the nearest integer.

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print(round(3.45)) # 👉️ 3 print(round(3.55)) # 👉️ 4 

# Convert a List of Floats to a List of Integers using math.ceil

If you need to round up, use the math.ceil() method.

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import math list_of_floats = [1.23, 3.45, 5.67] result = [math.ceil(item) for item in list_of_floats] print(result) # 👉️ [2, 4, 6] 

The math.ceil method returns the smallest integer greater than or equal to the provided number.

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print(math.ceil(3.01)) # 👉️ 4 print(math.ceil(3.99)) # 👉️ 4 

# Convert a List of Floats to a List of Integers using math.floor

If you need to round down, use the math.floor() method.

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import math list_of_floats = [1.23, 3.45, 5.67] result_4 = [math.floor(item) for item in list_of_floats] print(result_4) # 👉️ [1, 3, 5] 

The math.floor method returns the largest integer less than or equal to the provided number.

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print(math.floor(4.999)) # 👉️ 4 print(math.floor(4.001)) # 👉️ 4 

Alternatively, you can use the map() function.

# Convert a List of Floats to a List of Integers using map()

This is a three-step process:

1. Pass the round() function and the list to the map() function.
2. The map() function will pass each float to the round() function.
3. Use the list() class to convert the map object to a list.

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list_of_floats = [2.4, 3.5, 6.7, 8.1] new_list = list(map(round, list_of_floats)) # 👇️ [2, 4, 7, 8] print(new_list) 

The map() function takes a function and an iterable as arguments and calls the function with each item of the iterable.

The map() function calls the round() function will each floating-point number in the list and rounds each value.

The last step is to use the list() class to convert the map object to a list.

The list() class takes an iterable and returns a list object.

Which approach you pick is a matter of personal preference. I’d go with the list comprehension as I find it more direct and easier to read.

# Convert a List of Integers to a List of Floats in Python

To convert a list of integers to a list of floats:

1. Use a list comprehension to iterate over the list.
2. Use the float() class to convert each integer to a float.
3. The new list will only contain floating-point numbers.

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list_of_integers = [3, 5, 7, 9] new_list = [float(item) for item in list_of_integers] # 👇️ [3.0, 5.0, 7.0, 9.0] print(new_list) 

We used a list comprehension to iterate over the list of integers.

List comprehensions are used to perform some operation for every element, or select a subset of elements that meet a condition.

On each iteration, we pass the integer to the float() class to convert it to a floating-point number.

The new list will only contain float values.

Alternatively, you can use the map() function.

# Convert a List of Integers to a List of Floats using map()

This is a three-step process:

1. Pass the float() class and the list to the map() function.
2. The map() function will call the float() class with each item in the list.
3. Use the list() class to convert the map object to a list.

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list_of_integers = [3, 5, 7, 9] new_list = list(map(float, list_of_integers)) # 👇️ [3.0, 5.0, 7.0, 9.0] print(new_list) 

The map() function takes a function and an iterable as arguments and calls the function with each item of the iterable.

The float() class gets passed each integer in the list and converts each value to a floating-point number.

Lastly, we used the list() class to convert the map object to a list.

The list() class takes an iterable and returns a list object.

# Convert a List of Integers to a List of Floats using a for loop

You can also use a for loop to convert a list of integers to a list of floats.

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list_of_integers = [3, 5, 7, 9] new_list = [] for item in list_of_integers: new_list.append(float(item)) print(new_list) # 👉️ [3.0, 5.0, 7.0, 9.0] 

On each iteration of the for loop, we convert the current item to a floating-point number and append the result to a new list.

# Convert a List of Integers to a List of Floats using NumPy

This is a two-step process:

1. Pass the list and the float data type to the numpy.array() method.
2. Optionally convert the NumPy array to a list.

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import numpy as np list_of_integers = [3, 5, 7, 9] new_list = list( np.array(list_of_integers, dtype=np.float32) ) # 👇️ [3.0, 5.0, 7.0, 9.0] print(new_list) 

You can install NumPy by running the following command.

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pip install numpy # 👇️ or with pip3 pip3 install numpy 

The numpy.array method creates an array from the provided object.

We set the dtype argument to np.float32 to specify the desired data type for the elements in the array.

The last (optional) step is to use the list() class to convert the NumPy array to a list object.

The list() class takes an iterable and returns a list object.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

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