Float number to string python

Convert Float to String in Python

In this blog, we will learn how to convert float to string in Python with this comprehensive guide. Explore various methods such as str(), format(), f-strings, repr(), % operator, and the decimal module, along with examples and explanations.

Introduction:

In Python, data types such as integers, floating-point numbers, and strings are widely used in programming. Often, there is a need to convert one data type to another for various purposes, such as data manipulation, input/output handling, and data formatting. Converting a float to a string is a common operation in Python, and there are several methods available to achieve this task. In this blog, we will explore various methods to convert a float to a string in Python, with examples and explanations for each method.

Let’s start by discussing the different methods available to convert a float to a string in Python:

1. Using the str() Function:

The simplest and most straightforward way to convert a float to a string is by using the str() function, which is a built-in function in Python. The str() function takes a single argument, which is the float value that needs to be converted to a string. Here’s an example:

# Using the str() function float_num = 3.14 str_num = str(float_num) print(str_num) 

Output:

In the above example, the str() function is used to convert the float value 3.14 to a string. The resulting string ‘3.14’ is stored in the variable str_num . The print() function is then used to display the converted string value.

2. Using the format() Method:

Another way to convert a float to a string in Python is by using the format() method, which is a built-in method available for string objects. The format() method allows you to format a string by inserting values into placeholders. Here’s an example:

# Using the format() method float_num = 3.14 str_num = "<>".format(float_num) print(str_num) 

Output:

In the above example, the format() method is used to insert the float value 3.14 into the placeholder <> in the string. The resulting string ‘3.14’ is stored in the variable str_num , and the print() function is used to display the converted string value.

3. Using f-strings:

Introduced in Python 3.6, f-strings provide a concise and readable way to format strings with embedded expressions. You can use f-strings to directly convert a float to a string by including the float value inside the curly braces <> . Here’s an example:

# Using f-strings float_num = 3.14 str_num = f"" print(str_num) 

Output:

In the above example, the float value 3.14 is directly included inside the f-string, which is enclosed in the curly braces <> . The resulting string ‘3.14’ is stored in the variable str_num , and the print() function is used to display the converted string value.

4. Using the repr() Function:

The repr() function is another built-in function in Python that can be used to convert a float to a string. The repr() function returns a string that represents the printable version of an object. Here’s an example:

# Using the repr() function float_num = 3.14 str_num = repr(float_num) print(str_num) 

Output:

In the above example, the repr() function is used to convert the float value 3.14 to a string. The resulting string ‘3.14’ is stored in the variable str_num , and the print() function is used to display the converted string value.

5. Using the % Operator:

The % operator in Python is used for string formatting and can also be used to convert a float to a string. This method is similar to the one used in C’s printf function. Here’s an example:

# Using the % operator float_num = 3.14 str_num = "%s" % float_num print(str_num) 

Output:

In the above example, the %s is a placeholder that represents a string in the string format, and the % operator is used to replace the placeholder with the float value 3.14 . The resulting string ‘3.14’ is stored in the variable str_num , and the print() function is used to display the converted string value.

6. Using the decimal Module:

The decimal module in Python provides support for fast correctly rounded decimal floating-point arithmetic. This module can also be used to convert a float to a string with specific formatting options, such as precision and rounding. Here’s an example:

# Using the decimal module from decimal import Decimal float_num = 3.14 str_num = Decimal(float_num).to_eng_string() print(str_num) 

Output:

In the above example, the Decimal class from the decimal module is used to create a decimal object from the float value 3.14 , and the to_eng_string() method is used to convert the decimal object to a string representation. The resulting string ‘3.14’ is stored in the variable str_num , and the print() function is used to display the converted string value.

Conclusion:

In this blog, we explored various methods to convert a float to a string in Python. We covered methods such as using the str() function, the format() method, f-strings, the repr() function, the % operator, and the decimal module. Each method has its own advantages and can be used depending on the specific requirements of the task at hand. It is essential to choose the appropriate method based on factors such as ease of use, performance, and formatting options.

In conclusion, converting a float to a string in Python is a simple but crucial operation in many programming scenarios. By understanding the different methods available and their usage, you can effectively convert float values to string representations in your Python programs.

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Python Float to String

For concatenating the float with other strings, displaying the float as a string in the program’s output, or writing a file, the Python float is required to be converted to a string. Python provides various ways to convert a Python float to a string such as the “str()” function, “f-string” method, or “repr()” function, etc. In this Python guide, all of these methods are illustrated with appropriate examples

How to Convert Python Float to a String?

To convert a Python float to a string, the following approaches can be used:

Method 1: Convert Python Float to a String in Python by Applying the “str()” Function

Strings can be converted into any data type using the Python “str()” function. Here is the syntax:

• The “object” parameter is the object that needs to be converted into a string.
• The “encoding” parameter/attribute defines the encoding of the string. It defaults to ‘utf-8‘.
• The “errors” parameter specifies how errors should be handled while encoding the string. It defaults to ‘strict‘.

Example
The below code converts the specified float to a string:

float_value = 45.45
print ( float_value )
print ( type ( float_value ) , ‘ \n ‘ )
output = str ( float_value )
print ( output )
print ( type ( output ) )

In this example code, the “str()” function takes the specified float value as its parameter and yields the string representation.

Output

The above snippet shows that the given string has been converted/transformed into a Python string.

Method 2: Convert Python Float to a String in Python by Applying the “f-string” Method

In Python version “3.6”, the “f-string” method was introduced for formatting strings in Python. The “f-strings” is a string literal that starts with an “f” or “F” and is followed by curly braces “<>”. The curly braces are used as placeholders for variables that will be replaced/updated by their values at runtime.

Example
In the following code, the “f-string” method is used to convert the specified float to a string:

float_value = 45.45
print ( float_value )
print ( type ( float_value ) , ‘ \n ‘ )
output = f »
print ( output )
print ( type ( output ) )

Based on the above code snippet, the “f-string” method converts the specified float to a string in accordance with the provided decimal value.

Output

The above snippet implies that the float has been converted into a Python string appropriately.

Method 3: Convert Python Float to a String in Python Using the “repr()” Function

The “repr()” function retrieves a string description/representation of an object that can be used to recreate the object.

In the above syntax, the “obj” parameter is the object whose printable representation has to be returned. The “repr()” function produces a printable representational string of the input object.

Example
Let’s understand it by the following example code:

float_value = 789.45654
print ( float_value )
print ( type ( float_value ) , ‘ \n ‘ )
output = repr ( float_value )
print ( output )
print ( type ( output ) )

The above code shows that the “repr()” function takes the float as a parameter and converts it into a Python string.

Output

Based on the above outcome, the given float value has been converted into a Python string.

Conclusion

To convert a Python float to the specified string, the “str()” function, the “f-string” method, or the “repr()” function is used in Python. The “str()” function is a simple and efficient way to convert a Python float to a string. The “f-string” method and “repr()” function can also convert/transform the Python float to a string. This post presented various methods using appropriate examples to convert a float to a string in Python.

About the author

Talha Saif Malik

Talha is a contributor at Linux Hint with a vision to bring value and do useful things for the world. He loves to read, write and speak about Linux, Data, Computers and Technology.

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Converting a float to a string without rounding it

I’m making a program that, for reasons not needed to be explained, requires a float to be converted into a string to be counted with len(). However, str(float(x)) results in x being rounded when converted to a string, which throws the entire thing off. Does anyone know of a fix for it? Here’s the code being used if you want to know:

-1: No examples the required output for different values of x . Without examples, we can only guess what the problem is.

4 Answers 4

Some form of rounding is often unavoidable when dealing with floating point numbers. This is because numbers that you can express exactly in base 10 cannot always be expressed exactly in base 2 (which your computer uses).

In this case, you’re seeing .1 converted to a string using repr :

I believe python chops off the last few digits when you use str() in order to work around this problem, but it’s a partial workaround that doesn’t substitute for understanding what’s going on.

I’m not sure exactly what problems «rounding» is causing you. Perhaps you would do better with string formatting as a way to more precisely control your output?

>>> '%.5f' % .1 '0.10000' >>> '%.5f' % .12345678 '0.12346' 

However I must say that this isn’t as reliable as you think.

Floats are entered/displayed as decimal numbers, but your computer (in fact, your standard C library) stores them as binary. You get some side effects from this transition:

>>> print len(repr(0.1)) 19 >>> print repr(0.1) 0.10000000000000001 

The explanation on why this happens is in this chapter of the python tutorial.

A solution would be to use a type that specifically tracks decimal numbers, like python’s decimal.Decimal :

>>> print len(str(decimal.Decimal('0.1'))) 3 

Good post concerning how to work with float results from division: stackoverflow.com/questions/2958684/python-division

Other answers already pointed out that the representation of floating numbers is a thorny issue, to say the least.

Since you don’t give enough context in your question, I cannot know if the decimal module can be useful for your needs:

Among other things you can explicitly specify the precision that you wish to obtain (from the docs):

>>> getcontext().prec = 6 >>> Decimal('3.0') Decimal('3.0') >>> Decimal('3.1415926535') Decimal('3.1415926535') >>> Decimal('3.1415926535') + Decimal('2.7182818285') Decimal('5.85987') >>> getcontext().rounding = ROUND_UP >>> Decimal('3.1415926535') + Decimal('2.7182818285') Decimal('5.85988') 

A simple example from my prompt (python 2.6):

>>> import decimal >>> a = decimal.Decimal('10.000000001') >>> a Decimal('10.000000001') >>> print a 10.000000001 >>> b = decimal.Decimal('10.00000000000000000000000000900000002') >>> print b 10.00000000000000000000000000900000002 >>> print str(b) 10.00000000000000000000000000900000002 >>> len(str(b/decimal.Decimal('3.0'))) 29 

Maybe this can help? decimal is in python stdlib since 2.4, with additions in python 2.6.

Hope this helps, Francesco

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