[Tut] Easiest Way to Convert List of Hex Strings to List of Integers

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Easiest Way to Convert List of Hex Strings to List of Integers

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Question: Given a Python list of hexadecimal strings such as

Code:

['ff', 'ef', '0f', '0a', '93']

. How to convert it to a list of integers in Python such as

Code:

[255, 239, 15, 10, 147]

?

Easiest Answer



The easiest way to convert a list of hex strings to a list of integers in Python is the list comprehension statement

Code:

[int(x, 16) for x in my_list]

that applies the built-in function

Code:

int()

to convert each hex string to an integer using the hexadecimal base

Code:

16

, and repeats this for each hex string

Code:

x

in the original list.

Here’s a minimal example:

Code:

my_list = ['ff', 'ef', '0f', '0a', '93'] my_ints = [int(x, 16) for x in my_list] print(my_ints) # [255, 239, 15, 10, 147]

The list comprehension statement applies the expression

Code:

int(x, 16)

to each element

Code:

x

in the list

Code:

my_list

and puts the result of this expression in the newly-created list.

The

Code:

int(x, 16)

expression converts a hex string to an integer using the hexadecimal base argument

Code:

16

. A semantically identical way to write this would be

Code:

int(x, base=16)

.

In fact, there are many more ways to convert a hex string to an integer—each of them could be used in the expression part of the list comprehension statement.

However, I’ll show you one completely different approach to solving this problem without listing each and every combination of possible solutions.

For Loop with List Append

You can create an empty list and add one hex integer at a time in the loop body after converting it from the hex string

Code:

x

using the

Code:

eval('0x' + x)

function call. This first creates a hexadecimal string with

Code:

'0x'

prefix using string concatenation and then lets Python evaluate the string as if it was real code and not a string.

Here’s an example:

Code:

my_list = ['ff', 'ef', '0f', '0a', '93'] my_ints = [] for x in my_list: my_ints.append(eval('0x' + x)) print(my_ints) # [255, 239, 15, 10, 147]

You use the fact that Python automatically converts a hex value of the form

Code:

0xff

to an integer

Code:

255

:

Code:

>>> 0xff 255 >>> 0xfe 254 >>> 0x0f 15

You may want to check out my in-depth guide on this important function for our solution:

Recommended Tutorial: Python

Code:

eval()