How to check if a unicode string contains only numeric characters in Python?

In Python, Unicode strings can contain numeric characters from various languages and scripts. To check if a Unicode string contains only numeric characters, we can use built-in string methods, regular expressions, or character iteration.

These methods ensure that characters like Arabic numerals, Chinese digits, or superscripts are also recognized as valid numeric characters.

Using isnumeric() Method

The isnumeric() method returns True if all characters in the string are numeric, including Unicode numeric characters like ², ?, ?, etc. If any character is non-numeric or the string is empty, it returns False.

Example: Unicode Numeric Characters

In the following example, the string contains Devanagari digits which are valid Unicode numeric characters, so the isnumeric() function returns True -

str1 = "?????"  # Hindi numerals (Devanagari)

print("The given string is")
print(str1)

print("Checking if the string contains only numeric characters")
print(str1.isnumeric())

The output is shown below -

The given string is
?????
Checking if the string contains only numeric characters
True

Example: Mixed Characters

In the following example, the string includes a Latin digit and a non-numeric letter. So, the isnumeric() function returns False -

str2 = "123a"

print("The given string is")
print(str2)

print("Checking if the string contains only numeric characters")
print(str2.isnumeric())

The output is -

The given string is
123a
Checking if the string contains only numeric characters
False

Using Regular Expressions

You can use the re.fullmatch() function to match the string against a Unicode digit pattern. The pattern \d+ matches only ASCII digits, but by using the Unicode flag, it can match other digit characters too.

Example: Using Unicode-aware Regex

In the following example, the string contains Tamil digits. Since we are using the re.fullmatch() function with the Unicode flag, it returns True -

import re

str3 = "???"  # Tamil numerals

print("The given string is")
print(str3)

print("Checking if the string contains only numeric characters")
print(bool(re.fullmatch(r"\d+", str3)))

The result is -

The given string is
???
Checking if the string contains only numeric characters
True

Using Character-wise Check with unicodedata

The unicodedata module helps to identify if each character in a string is a numeric character or not by checking its Unicode category.

Example: Checking Character by Character

In the following example, we check each character using the unicodedata.numeric() function. If all characters can be converted to a number, the result is True -

import unicodedata

def is_all_numeric(text):
   try:
      for char in text:
         unicodedata.numeric(char)
      return True
   except (TypeError, ValueError):
      return False

str4 = "???"  # Arabic numerals

print("The given string is")
print(str4)

print("Checking if the string contains only numeric characters")
print(is_all_numeric(str4))

Output is as follows -

The given string is
???
Checking if the string contains only numeric characters
True