How to convert string to float python
How to convert string to float python
How To Convert String to Float in Python – Definitive Guide
You can convert string to float in Python using the float(str) method.
In this tutorial, you’ll learn how to convert python string to float using the float() method along with the exceptions to be handled and the number of decimal points to be retained.
If You’re in Hurry…
You can use the below code snippet to convert String to Float by using the float() method.
Output
To know more about the exceptions and the decimal points, read the tutorial.
If You Want to Understand Details, Read on…
Table of Contents
Python String to Float
You can convert String to float using the float() method.
To know the type of the variable in Python, you can use the type() method.
The below example type(str) displays the type of the st variable. Its class ‘str’ which means it’s a String variable.
Next, you’ll convert the st variable to float by using the float(st) method and the value is stored in the variable f. When you print the type of f, its class float which means it’s a float variable.
Output
Next, you’ll see the exception to be handled while using the float() method.
Exception
When using the float() method, it’ll throw the below exceptions.
Example
Output
To avoid this error, you need to catch the ValueError exception is shown in the next section.
Convert String to Float Exception
You need to enclose the float() method in try block. Then if there is an exception while converting a String to float, then the exception will be thrown.
In the below example, you’ll catch the ValueError exception and printing a proper message to the user.
Snippet
Output
This is how you can convert String to float with Exception handling.
Convert String to Float with 2 Decimal Points
In this section, you’ll convert String to Float with 2 decimal points.
Even if the String variable has more than two decimal points, you’ll convert it to float first using the float() method and then format the float number to have only 2 decimal points using the format() method.
Snippet
Output
This is how you can handle decimal points in the floating-point numbers.
Convert String With Comma to Float
You can convert a string number with a comma to float by replacing all the commas in the String.
By default, the float() method doesn’t handle String with Comma. Hence you need to replace the comma with an empty String and then pass it to the float() method as shown below.
Snippet
All the commas will be replaced to String and the resultant number will be converted to float as shown below.
Output
This is how you can convert String with a comma to a float number.
Convert String to Float With Default Value
In this section, you’ll learn how to convert String to float with the default value.
This means, when a String to float conversion fails, a default number should be returned to you.
Python doesn’t implicitly support a method to return a default value when the conversion fails. Hence, you’ll need to create a custom function to return a default value.
In the below example, it’ll return the default float value by using the float() method.
Since the input String contains a number with a comma, float conversion will fail. Then in the exception block, a default float value 0.0 is assigned to the variable and it’ll be returned to the calling function.
You’ll see the below output.
Output
This is how you can convert String to float with the default value.
Convert String to Float NaN
In this section, you’ll learn how to convert String to Float. If the conversion is failed due to invalid values, then you’ll assign the float NaN value.
NaN means Not a Number and it is used to denote the missing data.
NaN value is available in the NumPy package. You need to import the NumPy package using the below statement.
To assign NaN value to float in case of failed conversion, catch the ValueError that will be thrown when the String to Float conversion fails and assign the NaN value using np.nan as shown below.
Snippet
You’ll see the below output.
Output
This is how you can convert String to float Nan in case of invalid float numbers.
Convert String to Float Keep Precision
To convert String to float and keep precision as such, you can just use the float() method. It’ll convert the String object to a number and then display it as a float with the same precision.
Output
With Trailing Zeros
To preserve trailing zeros or add a required number of trailing zeros, you can use the format function. It’ll add the necessary number of zeros to make the number of the preferred length.
Snippet
Output
Conclusion
To summarize, you’ve learned how to convert String to float in Python.
Additionally, you’ve also learned how to
6 Ways to Convert String to Float in Python
When you take a user input in python programming while working with terminal or file operations like reading or writing a file, the input is a string object. Even though you ask for the floating-point value, the input method in python will fetch the user input as a string object. Hence, you have to explicitly convert the string into a floating-point value so that you can perform the necessary operations on it. Before understanding the methods to convert the string to float explicitly, let us first go through the strings and float data types in python.
What are strings in python?
A string is a series of characters inside the quotes. You can use single quotes or double quotes to display the string. Also, triple quotes are used to display the multi-line quotes.
As you know, that computer does not deal with characters but instead, it works only with binary numbers. Therefore, the characters you input in the system are converted into a binary format using the encoding techniques like Unicode and ASCII. In python, the string is a sequence of Unicode characters which include every character and symbol in all languages. Square brackets are used to access the string elements along with the index position of the string character. The indexing of character in a string starts from ‘0’, and therefore, the string’s first character always has the index equal to zero.
For Example
Output
What is Float in python?
For Example
Output
Convert String to Float in Python
Below are 6 common and simple methods used to convert a string to float in python
1) Using float() function
You can use the float() function to convert any data type into a floating-point number. This method only accepts one parameter. If you do not pass any argument, then the method returns 0.0. If the input string contains an argument outside the range of floating-point value, OverflowError will be generated.
For Example
Output
If the input string contains anything other than a floating-point representation of a number, the output will be ValueError. Let us understand this in detail below.
2) Convert a Number String with commas into a floating-point object
Consider that the input string is ’1,0.123′. As you can see, the string contains numbers, but it also has a comma in it. Therefore, converting this kind of string into a floating-point value is very tricky. If you directly call the float() method, then the output will raise an error.
For Example
Output
You have to remove all the commas from the string before calling the float() function to solve this issue. Take a look at the example below to understand better.
For Example
Output
3) Convert string to float list in python
In this method, firstly, you need to initialize the string, and later, you can use the float() and split() method to convert a string into the floating-point list, as shown below in the example.
For Example
Output
4) Convert a list of strings to float in python
The list of strings is the python list containing all elements as strings in it. To convert this list of strings into floating-point values, you have to use for loop to iterate through each item of the list. Later, you can use the float() method to convert each item into float value and then append it to the list again. Check out the below example for reference:
For Example
Output
5) Convert String to Float using Numpy
Numpy is one of the libraries for python programming, which supports large, multi-dimensional arrays and matrices to perform high-level mathematical operations. If you want to convert a string into float using NumPy, the first step will be to import the NumPy library using “import NumPy as np.” Later, you can use the “astype” method, an in-build method used to convert the string to a floating-point value in python.
For Example
Output
6) Convert String to Float with Specified Decimal Points
It is often necessary to bring the precision for the number of zeros after the decimal in floating-point values. In such cases, you can use the float() method to convert a string into float value and then use the format() method to specify the number of decimal points in the float value. The syntax of the format method is as given below:
“<:.Nf>”.format(float value)
Here, N displays the number of decimal points you wish to put. If the floating-point value generated has fewer decimal points than the suggested, then zeros are added at the end to round it. Take a look at the example below for a better understanding.
Example
Output
Conclusion
While programming, there are many situations where you have to convert one data type into another to perform the necessary operations. This article refers to the python string and float values in detail and the explicit methods used to convert strings into floating-point values. As the input method in python accepts the string object for user input, it is necessary to learn and understand these methods to convert the string into float data type to perform different operations on user data.
Convert string to float in Python + Various Examples
In this python tutorial, you will learn about how to convert string to float in python and, also we will check:
How to convert string to float python
Let’s see how to convert string to float in python.
In this example, we will use built-in float() function to convert string to float in python.
Example:
You can refer to the below screenshot to see the output for how to convert string to float python.
The above code we can use to convert string to float in python.
How to convert string to float list in python
Here, you will see how to convert string to float list in python.
Firstly, we need to initialize the string and then we will use float() and split() methods to perform the task. In the below example we have converted the string to a float list.
Example:
You can refer to the below screenshot to see the output for how to convert string to float list in a python.
This is how to convert string to float list in python.
How to convert comma separated string to float python
Here, we will see how to convert comma separated string to float python.
In this example, we have a string ‘345,567,891.809’, which contains the number and also we have some extra commas. Here, we will use .replace(‘,’, ”) to remove all comma from string before passing it to float function.
Example:
You can refer to the below screenshot to see the output for how to convert comma separated string to float python.
Here, we know, how to convert comma separated string to float python.
How to convert input string to float in python
Now, we will see how to convert input string to float in python.
To convert the input string to float in python we will first take input from the user, and the float() method is used to convert.
Example:
You can refer to the below screenshot to see the output for how to convert the input string to float in python.
The above Python code, we can use to convert input string to float in python.
Convert list of string to float python
Let’s see how to convert list of string to float python.
In this example, we will convert a list of strings to float and we will use a for-loop to iterate throughout the list. Also, we will append the converted item to a new list.
Example:
You can refer to the below screenshot to see the output for how to convert list of string to float python.
This is how to convert list of string to float python.
How to convert string array to float array in python
Now, we will see how to convert string array to float array in python
Firstly, we need to import numpy as np. The asarray() is numpy function that converts the string array to a float array of a specified type in python.
Example:
You can refer to the below screenshot to see the output for how to convert string array to float array in python
The above python code, we can use to convert string array to float array in python.
How to convert string to float in python using numpy
Here, we will see how to convert string to float in python using numpy.
Firstly, we need to import numpy as np. The astype is a built-in class function of numpy which is used to convert string to float in python using numpy.
Example:
You can refer to the below screenshot to see the output for how to convert string to float in python using numpy.
The above python code we can use to convert string to float in python using numpy.
How to convert a string with commas to a float in python
Now, we will see how to convert a string with commas to a float in python
In this example, we have a string ‘20,188.23’, which contains the number and also we have single commas. Here, we will use .replace(‘,’, ”) to remove the comma from string before passing it to float function.
You can refer to the below screenshot to see the output for how to convert a string with commas to a float in python.
This is how to convert a string with commas to a float in python.
How to convert string with decimal to float in python
Let us see how to convert string with decimal to float in python.
Firstly, we need to import from decimal import * and then we will use the Decimal() module. To get the output we will use print(val).
Example:
You can refer to the below screenshot to see the output for how to convert string with decimal to float in python.
The above code is used to convert string with decimal to float in python.
How to convert string with letters to float in python
Now, we will see how to convert string with letters to float in python.
To convert string with letters to float in python we will use split the string at £ and then we have to convert the second substring to a float.
Example:
You can refer to the below screenshot to see the output for how to convert string with letters to float in python.
This is the python code to convert string with letters to float in python.
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Python String to float, float to String
In this article, we will be dealing with the conversion of Python String to float and vice-versa. In the daily programming practices, many times we come across scenarios wherein we feel the need to convert the type of data we are dealing with.
Python String to float
Python provides us with the built-in float() method to convert the data type of input from String to float.
Syntax:
Example:
Output:
Python NumPy String to float
NumPy module has got astype() method to convert the type of data.
The astype() method converts the type of the input data to the data type specified in the parameter.
Syntax:
Example:
Output:
Pandas String to float
Pandas module also uses astype() function to convert the data type of a particular field of the data set to the specified type.
Syntax:
Input csv file:
Example:
Output:
Python float to String
Python String has built-in str() method to convert the input data of any type to the String form.
Syntax:
Example:
Output:
Python NumPy float to String
List Comprehension can be used to convert Python NumPy float array to an array of String elements.
Syntax:
Example:
In the above snippet of code, “%.2f” will give me precision up to two decimals in the output array.
Output:
Conclusion
In this article, we have understood the conversion of data from String to float form and vice-versa with Python Data structures.
Python Convert String to float
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We can convert a string to float in Python using the float() function. This is a built-in function used to convert an object to a floating point number. Internally, the float() function calls specified object __float__() function.
Python Convert String to float
Let’s look at a simple example to convert a string to float in Python.
Why do we need to convert a string to float?
If we are getting float value from user input through the terminal or reading it from a file, then they are string objects. We have to explicitly convert them to float so that we can perform necessary operations on it, such as addition, multiplication, etc.
Ideally, we should use try-except block to catch exceptions in case of invalid input from user. If you are not familiar with string formatting using f prefix, please read f-strings in Python.
Python Convert float to String
We can convert float to a string easily using str() function. This might be required sometimes where we want to concatenate float values. Let’s look at a simple example.
If we don’t convert float to string in the above program, the join() function will throw an exception. Also, we won’t be able to use + operator to concatenate as it will add the floating point numbers.
You can checkout complete python script and more Python examples from our GitHub Repository.
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