Convert String to Float in Python

We are quite familiar with the data types available in Python and what kind of different operations we can perform on them.

We know that,

Strings are a sequence of characters that are denoted using inverted commas ”. They are immutable which means they cannot be changed once declared.

And float values are nothing but the decimal values.

We can check the types using the program given below-

Output:

<class 'float'>
<class 'str'>

In this tutorial, we will discuss the different scenarios of converting a string to float in Python.

1. Using float function
2. Converting a string with commas
3. Converting to a float list
4. Converting a list of strings to float
5. Converting using NumPy
6. Converting in specified decimal points

Using Float Function

Let us look at the first case where we will use the float function,

The following program illustrates the same-

Output:

The float value is 2.71

Explanation:

Let’s understand what we have done in the above program-

1. The first step is to declare the string value that we would like to convert.
2. After this, we will make use of a float() in which we’ll then pass the variable that holds the string value.
3. On executing the program, we can observe that it displays the required value.

Converting a String with Commas

Let us look at the second case where we will convert a string with commas,

The following program illustrates the same-

Output:

The float value is 2.71

Explanation:

Let’s understand what we have done in the above program-

1. The first step is to declare the string value that we would like to convert, this time a comma is present before the decimal point.
2. After this, we will make use replace() inside float() in which we’ll specify both, the value we would like to replace and with what it would be replaced.
3. On executing the program, we can observe that it displays the required value.

Converting to a Float List

Let us look at the third case where we will convert the string to a float list,

The following program illustrates the same-

Output:

The list having float values: [ 1.21, 2.34, 3.42, 9.22, 5.43]

Explanation:

Let’s understand what we have done in the above program-

1. The first step is to declare the string value that we would like to convert, this time there is a list of different decimal values separated with a comma.
2. After this, we will make use of list comprehension that will take each value and convert it into the required type.
3. On executing the program, we can observe that it displays the required value.

Converting List of Strings to Float

Let us look at the fourth case where we will convert list of strings to float,

The following program illustrates the same-

Output:

The list having float values: [ 1.21,2.34,3.42,9.22,5.43] 

Let’s understand what we have done in the above program-

1. The first step is to declare the list that contains all the string values as it’s elements
2. After this, we have declared an empty list and used for loop that takes each element, converts it into float value, and appends it into res.
3. On executing the program, we can observe that it displays the required value.

Converting Using NumPy

Let us look at the fifth case where we will convert the string using numpy,

The following program illustrates the same-

Output:

The list having float values: [1.21 2.34 3.42 9.22 5.43 ]

Explanation:

Let’s understand what we have done in the above program-

1. The first step is to import the numpy library as np.
2. After this, we have declared the array that has all the string values.
3. Once this is done, the next step is to use astype() and specify float in it since this is the functionality/feature we wish to apply on all the elements.
4. On executing the program, we can observe that it displays the required value.

Converting in Specified Decimal Points

Finally, in the last program we will see how we can convert a string to specified decimal points,

The following program illustrates the same-

Output:

2.89

Explanation:

Let’s understand what we have done in the above program-

1. The first step is to declare the string value that we would like to convert.
2. After this, we will make use of a float() and pass the variable x.
3. Since we want our output in two decimal places, we will mention this in the next statement.
4. On executing the program, we can observe that it displays the required value.

Conclusion

So, in this tutorial, we understood the different scenarios and learned approaches to convert a string to float in Python.