How to convert string to float in python

Python Convert String to Float

How to convert a String to Float in Python? Converting a string to a float is a common operation, especially when working with numerical data stored in text files or received as input. In this article, we will look at various techniques for converting a string to a float in Python. The simple method is using the float() function, which is not always the solution. So let’s discuss it in detail.

Quick Examples of Converting String to float

If you are in a hurry, below quick examples will help you in understanding the different ways to convert a string to a float in Python. We will discuss them in detail with other important tips.

1. The Difference between String and Float in Python

In Python String and float are two different types of datatypes. Here are three points that can show the differences between strings and floats in Python:

• Type: A string is a sequence of characters, represented as a str object in Python. A float is a numerical value with a decimal point, represented as a float object in Python.
• Representation: A string is represented by enclosing a sequence of characters in single or double quotes, like this: ‘Hello, World!’ or «3.14159» . A float is represented by a numerical value with a decimal point, like this: 3.14159 .
• Usage: Strings are typically used to represent text data, such as names, addresses, or messages. Floats are typically used to represent numerical data, such as measurements or calculations.

2. Convert String to Float using float() Function

The float() function is a built-in function in Python that converts a string or a number to a float type. It is a simple and widely used method for converting a string or a number to a float.

The float() function is flexible and can handle a variety of string formats. As long as they contain a valid float representation. For example, you can use the float() function to convert strings with leading or trailing spaces. It can also convert strings that contain a leading or trailing plus or minus sign.

3. Convert String Representing Binary to Float

The float() function is of course more powerful but it can only convert strings to floats in base 10. So if you want to binary float representing in string format. You need to use another approach.

These are the steps that you can follow to Convert string representing binary decimal values to float.

1. Split the string into the integer part and the fractional part using the split() method.
2. Use the int() function to convert the integer part of the binary string to an integer in base 2.
3. Iterate over the fractional part of the string and convert each binary digit to a float.

4. Convert String Non Base 10 Values to Float

Just like in the above example, we can convert any string representing any base to float. We can follow the same formula we applied to the binary values in the above example.

Check the following example we have converted a string that represented a base 16 value to float.

 1 else "" # Convert integer part to float for i, c in enumerate(integer_part): value = value * base + int(c, base) # Convert fractional part to float fraction = 0.0 for i, c in enumerate(fraction_part): fraction += int(c, base) / (base ** (i + 1)) # Add integer and fractional parts value += fraction # Return value with correct sign return value * sign # Convert string to base 16 float string = "FF.7" base = 16 float_value = parse_float(string, base) print(float_value) # Output: # 255.4375 

5. Convert String to Float using Decimal Module

The decimal module in Python can be useful if you need to perform precise calculations with decimal values. It supports arbitrary-precision decimal arithmetic. It can avoid the round-off errors that can occur when using the built-in float type.

")) # Convert decimal value to float float_value = float(decimal_value) print(float_value) # Output: # 123.457 

6. Using Regular Expression to Convert String to Float

A regular expression is used to find and extract specific patterns of characters from a string. We can use a regular expression to match and extract the float value from a string in Python. We can use the re module and the search() function to find a float value in the string. Once we find the float value we can use the float() function to do the conversion.

7. Use float.fromhex() to Convert Hexadecimal Format to a Float

In previous examples, we have seen how the conversion from string to float that are not in base 10. Yet we have another function that can help us do the conversion on base 16.

To use the float.fromhex() method, you simply pass the string in hexadecimal format as an argument. This method is useful for converting hexadecimal floating-point literals.

8. Handle Exceptions when Converting String to Float

The built-in float() function can raise a ValueError exception if it is passed a string that cannot be converted to a float. We can enclose the conversion code in a try block and use an except block to catch the ValueError exception.

9. Tips to Convert String to Float in Python

There are several ways to do this conversion, and it is important to choose the method that best meets your needs. We have discussed a few of them. Here are a few points that you should keep in mind while doing the conversion from string to float.

1. The built-in float() function is the easiest and most straightforward way to convert a string to a float in Python.
2. If you need to perform precise decimal calculations, use the decimal module to convert a string to a float.
3. Use a regular expression to extract a float value from a string.
4. Use the float.fromhex() method to convert a hexadecimal string to a float.
5. Use the try and except statements to handle exceptions

Summary and Conclusion

You should now have everything you need to effectively convert string to float in your Python programs. If you have any questions, please don’t hesitate to leave a comment. I would be happy to help!

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How to Convert String to Float in Python?

When working with terminal or file operations in Python programming, such as reading or writing a file, the user input is a string object. Although you requested a floating-point value, Python’s input function returns the user input as a string object. As a result, you must explicitly convert the string to a floating-point value in order to do the required operations. Changing data types in Python is a common practice, and Python includes functions to make this easier.

Convert String to Float Value in Python

In Python, the default values that are fed by the user as the input are in string format, and many times we have to deal with the floating point, so we would have to explicitly convert the string values to float values. This can be done using several ways, such as by using the float function.

The conversion to float value can also be done using the NumPy, and the conversion can also be some specified format such as fixed decimal point conversion or converting the strings with a comma to floating-point values. Here we would see how we can convert the list of strings to float values. Several different methods which we would be learning several ways along with different examples to convert the string to float such as:-

1. Using float() function
2. Convert string having comma to a floating-point value
3. Convert the list of strings to float
4. Conversion to float value using the Numpy
5. Conversion to specified decimal point from string

Using float() Function

float() function is the most common way to convert the string to the float value. The float function takes the parameter y , which is a string, and would then convert the string to a float value and return its float value. While using the float function, we should keep in mind that the parameter y should have only the decimal value or the integer values, which can be converted to float value by the float function.

The value 0.0 is returned in the case when there is no argument provided to the function. Overflow error is given when the argument that is given as input cannot be contained by the floating-point data type.

Convert a Number String with Commas into a Floating-point Object

If we have the string which contains a comma such as 1,2.56 , we can not directly convert the string to float using the float() function as there the condition was that the parameter should only be in integer or decimal form, so we would have to firstly remove the comma and then use the flat function to convert the string value which contains the comma or decimal point to float value.

For removing the comma from the string, we would be replacing the comma with «» which would remove the comma from the string.

Convert String to Float List in Python

If the string contains multiple float values, then we would have to, one by one, iterate over the value s in the string separated by a comma and then convert them to float values.

For example the string value be s=34.25, 36.24, 15.26, 47.51, 97.51 the the float list would contain the values [34.25, 36.24, 15.26, 47.51, 97.51]

Convert a List of Strings to Float in Python

For converting the list of strings to a floating value list, we would have to iterate the string list and take the values one by one and then convert the string values to the floating values and then append all the float values to the floating value list.

For example the string list contains the value s=[‘34.25’, ‘36.24’, ‘15.26’, ‘15.48’, ‘15.30’] and the resulting float values would be [34.25, 36.24, 15.26, 15.48, 15.30]

Convert String to Float Using Numpy

Numpy is a python library that allows users to execute high-level mathematical operations on massive, multi-dimensional arrays and matrices. The first step in using NumPy to convert a string to a float is to import the NumPy library, which would be used to convert the string to the float values. Later, you can convert the string to a floating-point value in Python using the astype method, which is an in-built technique.

Convert String to Float with Specified Decimal Points

For converting the string to specified string to some specified decimal points, we would first be converting the values to the float values and then converting the float values to some specified decimal values. We would be using the format() function, which has the syntax .format(float value) where Nf is the number of values that must be present after the decimal in the floating value.

Conclusion

• Many times while writing python programs, we have to deal with the float values, and generally, when we take the input from the user, the default datatype is a string, and then we have to convert it to float type.
• For converting the string to float type, we have discussed several methods above, such as:*
  • String to float
  • List of strings to float
  • String with a comma to float
  • Float having specified decimal format

  For all above types of conversion, we have used the simple basic approach:

  • Convert the string values into the form of an integer and a decimal.
  • In case the string is a list, we would have to iterate over the string and deal with each value separately.
  • For converting string value to float, we have used the float() function to convert the string value to the float value.
  • For converting float values to the specified decimal format, we can use the format() function.

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