String to decimal number python

Convert a string to a number (int, float) in Python

In Python, you can convert a string str to an integer int and a floating point number float with int() and float() .

Use str() to convert an integer or floating point number to a string.

If you want to change the format of strings or numbers, use the format() function or the format() method of str .

You can also convert a list of strings to a list of numbers.

Convert a string to int : int()

int() converts a string to an integer int .

print(int('100')) print(type(int('100'))) # 100 # 

A string containing . or , raises an error.

# print(int('1.23')) # ValueError: invalid literal for int() with base 10: '1.23' # print(int('10,000')) # ValueError: invalid literal for int() with base 10: '10,000' 

To convert a comma-separated string, you can remove the commas by replacing them with an empty string » using replace() .

print(int('10,000'.replace(',', ''))) # 10000 

For more information on replace() , see the following article.

Convert a string to float : float()

float() converts a string to a floating point number float .

print(float('1.23')) print(type(float('1.23'))) # 1.23 # 

A string without the integer part can also be converted.

A string representing an integer is also converted to a floating point number float .

print(float('100')) print(type(float('100'))) # 100.0 # 

Convert binary, octal, and hexadecimal strings to int

If you pass a base number as the second argument of int() , the string will be treated as binary, octal, or hexadecimal, depending on the base.

print(int('100', 2)) print(int('100', 8)) print(int('100', 16)) # 4 # 64 # 256 

If the base is omitted, the string will be treated as decimal, as shown in previous examples.

print(int('100', 10)) print(int('100')) # 100 # 100 

If the base is 0 , it is converted based on the string’s prefix ( 0b , 0o , 0x or 0B , 0O , 0X ).

print(int('0b100', 0)) print(int('0o100', 0)) print(int('0x100', 0)) # 4 # 64 # 256 

Prefixes and hexadecimal letters can be written in either upper or lower case.

print(int('FF', 16)) print(int('ff', 16)) # 255 # 255 print(int('0xFF', 0)) print(int('0XFF', 0)) print(int('0xff', 0)) print(int('0Xff', 0)) # 255 # 255 # 255 # 255 

For more information on the interconversion of binary, octal, and hexadecimal strings to int , see the following article.

Convert exponential notation strings to float

You can convert a string in exponential notation to float with float() .

print(float('1.23e-4')) print(type(float('1.23e-4'))) # 0.000123 # print(float('1.23e4')) print(type(float('1.23e4'))) # 12300.0 # 

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Convert String to Decimal in Python

1. Use the float() Function to Convert a String to Decimal in Python
2. Use Exception Handling Convert a String Containing a Comma to a String in Python
3. Use String Formatting Along With the float() Function to Convert a String to Decimal in Python
4. Use List Comprehension to Convert a List of Strings to Float in Python
5. Use numpy.float() Function to Convert a String to Decimal in Python
6. Use the astype() Method From the NumPy Library to Convert a String to Decimal in Python
7. Use the decimal Module to Convert a String to Decimal in Python

Strings in Python can take numeric values. Similar to other popular programming languages, Python supports Integer and Floating-point (or decimal) numbers and has separate data types assigned for them. Sometimes, there is a need for converting the numeric values taken in a string to an integer or a floating-point number.

This tutorial will introduce how to convert a string to a decimal in Python.

Use the float() Function to Convert a String to Decimal in Python

Python provides an in-built function called float() that is utilized to transform a string or an integer to a floating-point value.

Here, we will enter a string and perform the float() function on the given string.

The following code uses the float() function to convert a string to decimal in Python.

The above code provides the following output:

Use Exception Handling Convert a String Containing a Comma to a String in Python

When a comma separates the numbers in the string and the float() function is directly called on the string, then it gives a ValueError .

The following example code will help you understand it better.

The above code provides the following output:

Traceback (most recent call last):  File "", line 2, in ValueError: could not convert string to float: '1,5.54' 

We can take a quick detour from the original code and use exception handling in this code to avoid this.

• The try block contains the cluster of code to be tested for any errors.
• The except block is used to add exceptions and handle the errors of the code.
• The finally block contains the statements that need to be executed and is ignored by the try and except blocks.

The following code utilizes exception handling on the original code given above to convert a string to decimal in Python.

a = "1,5.54" try:  x = float(a) except ValueError:  print("Invalid Float number to be converted. ") 

The above code provides the following output:

Invalid Float number to be converted. 

Use String Formatting Along With the float() Function to Convert a String to Decimal in Python

In a given string, if we want to specify the number of decimal points that we want to have in the floating-point variable, then we can use string formatting along with the in-built float() function.

The following code uses string formatting to convert a string to decimal in Python.

a = "5.54231" x = float(a) x = " ".format(x) print(x) 

The above code provides the following output:

Use List Comprehension to Convert a List of Strings to Float in Python

List comprehension is a relatively shorter and very graceful way to create lists that are to be formed based on given values of an already existing list.

We can use list comprehension and convert all the values within the list to floating-point values using the float() method in the list comprehension.

The following code uses list comprehension to convert a list of strings to float in Python.

lst= [ '1.22', '5.54', '6.858'] x = [float(i) for i in lst] print(x) 

The above code provides the following output.

Use numpy.float() Function to Convert a String to Decimal in Python

The term NumPy is an acronym for Numerical Python. This library makes the use of arrays possible in Python. It also provides functions that help in manipulating these arrays.

The numpy.float() function works similarly to the in-built float() function in Python, with the only difference being that the numpy.float() function is made to work with arrays. It always generates an array of floating-point values.

The following code uses the numpy.float() function to convert a string to decimal in Python.

import numpy as np lst= [ '1.22', '5.54', '6.858'] print(list(np.float_(lst))) 

The above code provides the following output:

Use the astype() Method From the NumPy Library to Convert a String to Decimal in Python

The NumPy library contains an in-built astype() method that assists in converting the data type of the given NumPy array.

The following code uses the astype() method from the NumPy library to convert a string to decimal in Python.

import numpy as np a = np.array(["1.22", "5.54", "6.858"]) x = a.astype(float) print(x) 

The above code provides the following output:

Use the decimal Module to Convert a String to Decimal in Python

The decimal module supplies functions that perform faster operations than the stock floating-point functions.

The decimal.Decimal() function, which is a constructor, takes input as a numeric value and carries out the process to convert it to a decimal type, which is ideal for storing and representing the numeric values meanwhile strictly preserving the precision of the number.

The following code uses the decimal module to convert a string to decimal in Python.

from decimal import Decimal a = '5.54262' x = Decimal(a) print(x) 

The above code provides the following output:

Vaibhhav is an IT professional who has a strong-hold in Python programming and various projects under his belt. He has an eagerness to discover new things and is a quick learner.

Related Article — Python String

Related Article — Python Float

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Python Conversion Guide: How to Convert a String to a Decimal Number in Python

Learn various methods to convert a string to a decimal number in Python. This conversion guide covers decimal module, int() function, float() function, built-in functions, and locale-aware methods.

Python is a popular programming language used for various applications, including data analysis, web development, and artificial intelligence. One of the common tasks in Python is to convert a string to a decimal number. In this blog post, we will discuss various methods to convert a string to a decimal number in Python.

Using the decimal module

The decimal module in python provides support for decimal floating-point arithmetic. The Decimal() function can be used to convert a string to a decimal number after replacing any commas with decimal points. The precision of decimal numbers can be controlled using the Decimal() function and formatting.

from decimal import Decimalstring_number = "3,14159265359" decimal_number = Decimal(string_number.replace(",", ".")) print(decimal_number) 

Using the int() function

The int() function can be used to convert any base to a decimal number. The int() function supports conversion of any number to any base. Python can also convert between binary and octal numbers using built-in functions.

string_number = "1010" decimal_number = int(string_number, 2) print(decimal_number) 

BINARY TO DECIMAL

Using the float() function

The float() function can be used to convert a string or integer to a floating-point value. The float() function returns a floating-point number but may have precision issues with certain decimal numbers.

string_number = "3.14159265359" float_number = float(string_number) print(float_number) 

Using built-in functions for conversions

Python has built-in functions to convert between binary, hexadecimal, and decimal numbers. The bin() function can be used to convert from a decimal value to its corresponding binary value. The hex() function can be used to convert a decimal number to its corresponding hexadecimal form.

decimal_number = 10 binary_number = bin(decimal_number) hexadecimal_number = hex(decimal_number) print(binary_number) print(hexadecimal_number) 

Using locale-aware methods

Locale-aware methods can be used to convert decimal marks in numbers. The locale module can be used to perform locale-aware string formatting.

import localestring_number = "3,14159265359" locale.setlocale(locale.LC_ALL, "en_US.UTF-8") decimal_number = locale.atof(string_number) print(decimal_number) 

Other useful code examples for converting string to decimal number in Python

x = 13.949999999999999999 g = float("".format(x))

In python, decimal to int python code example

print "%.4f" % 3.3333333333 3.3333 print "%.4f" % 6.6666666666 6.6667

Conclusion

Converting a string to a decimal number is a common task in Python. the decimal module in python provides support for decimal floating-point arithmetic. Python also has built-in functions to convert between binary, hexadecimal, and decimal numbers. The int() function can be used to convert any base to a decimal number. The float() function can be used to convert a string or integer to a floating-point value. Locale-aware methods can be used to convert decimal marks in numbers.

Frequently Asked Questions — FAQs

What is a decimal number in Python?

Decimal numbers in Python are floating-point numbers that provide precise decimal arithmetic. They can be used for financial calculations and other applications requiring accuracy.

Why do I need to convert a string to a decimal number in Python?

Strings are commonly used to represent numbers in Python, but they cannot be used for arithmetic operations. Converting a string to a decimal number allows you to perform mathematical operations and calculations.

What is the decimal module in Python?

The decimal module in Python provides support for decimal floating-point arithmetic. It allows for precise decimal calculations and rounding.

How do I use the int() function to convert a string to a decimal number in Python?

The int() function can be used to convert any base to a decimal number. To convert a string to a decimal number, use int(string, base).

How do I use the float() function to convert a string to a decimal number in Python?

The float() function can be used to convert a string or integer to a floating-point value. To convert a string to a decimal number, use float(string).

What are locale-aware methods in Python?

Locale-aware methods are used to perform string formatting and conversions that are sensitive to the user’s locale settings. They can be used to handle decimal marks in numbers and other localized formatting.

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