String array to number python

Convert String Array to Int Array in Python

This tutorial will demonstrate how to convert string array to int array in Python.

Using the for loop with int() function

To convert string array to int array in Python:

• Use the for loop to loop through the array.
• Use the int() function to convert each element to an integer in every iteration.

In the above example, we iterated over a list and converted each element individually to an integer using the int() function. Each element was appended to an empty list using the append() function.

We can perform the above operation more efficiently by using the list comprehension technique. This method is used to create a list using a for loop in a single line of code.

Using for loop with eval() function

Use the eval() function to convert string array to int array in Python

The eval() function accepts a Python string and evaluates it as a Python expression. We can use it in place of the int() function in the previous method.

Further reading:

Convert String to Char Array in Python

Convert byte array to String in Python

Using the map() with list() function

To convert string array to in array in Python:

• Use the map() function to apply the int() function to all elements of the array.
• Use the list() function to convert the map type object to a list.

The map() function can be used to apply the int() function to all the elements of the array. In Python 3, the map() function returns a map type object which can be converted to a list. In Python 2, this function directly returns a list.

Conclusion

To conclude, we discussed several methods to convert string array to int array in Python.

In the first method, we used a for loop to iterate over the array and convert each element to an integer using the int() function. This can be achieved efficiently using the list comprehension technique.

In the second method, we replaced the int() function with the eval() function. In the final method, we discussed the use of the map() function to apply the int() function to every element of the array.

That’s all about how to convert String array to int array in Python.

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How to Convert List of Strings to Ints in python : 4 Methods

Do you want to Convert List of Strings to Ints in python? If yes then you have come to the right place. In this entire post, you will know the various methods to convert the list of strings to int in python.

Methods to Convert List of Strings to Ints in python

Before going to the methods let’s create a sample list of strings. The list contains all the numerical values, but of string type. Let’s create them.

You can see in the above figure all the numerical values are in a single quote. It clearly represents that all these are strings.

Method 1: Convert String Array to Int array using python map

In this method, I will use the Python map() function to achieve the results. Just pass your string array and typecast the results to the list(). And you will get the list of int.

Execute the following code.

Output

Method 2: Convert List of strings to ints using list comprehension in python

The second method to convert string to int is using the list comprehension in python. Inside the list comprehension, there will be a loop that converts a string to int.

Execute the following code.

Method 3: Convert List of strings to ints using a new list

You can also convert list of strings to ints by using the new or fresh list. After that, you have to append all the converted strings to that list. And if you print the new list, you will get all the values as int.

You can see in the above code in each iteration of the loop, the value is typecasting to int and appending to the int_list.

Output

Method 4: Convert strings to ints in python using NumPy array

In this method, I will use the NumPy python module for conversion. First I will convert the strings list to NumPy array. And then change the type of the array to int using the astype(“int”). Lastly, convert it again to the list.

Execute the following lines of code.

Output

Conclusion

These are the methods to Convert List of Strings to Ints in python. All methods are great and it depends on your usage. Hope We have solved your queries you are searching for. Even if you have any queries then you can contact us for more information. We are always ready to help you.

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Python Convert String to Int – How to Cast a String in Python

Dionysia Lemonaki

When you’re programming, you’ll often need to switch between data types.

The ability to convert one data type to another gives you great flexibility when working with information.

There are different built-in ways to convert, or cast, types in the Python programming language.

In this article, you’ll learn how to convert a string to an integer.

Data types in Python

Python supports a variety of data types.

Data types are used for specifying, representing, and categorizing the different kinds of data that exist and are used in computer programs.

Also, different operations are available with different types of data – one operation available in one data type is often not available in another.

One example of a data type is strings.

Strings are sequences of characters that are used for conveying textual information.

They are enclosed in single or double quotation marks, like so:

fave_phrase = "Hello world!" #Hello world! is a string,enclosed in double quotation marks 

Ints, or integers, are whole numbers.

They are used to represent numerical data, and you can do any mathematical operation (such as addition, subtraction, multiplication, and division) when working with integers.

Integers are not enclosed in single or double quotation marks.

fave_number = 7 #7 is an int #"7" would not be an int but a string, despite it being a number. #This is because of the quotation marks surrounding it 

Data type conversion

Sometimes when you’re storing data, or when you receive input from a user in one type, you’ll need to manipulate and perform different kinds of operations on that data.

Since each data type can be manipulated in different ways, this often means that you’ll need to convert it.

Converting one data type to another is also called type casting or type conversion. Many languages offer built-in cast operators to do just that – to explicitly convert one type to another.

How to convert a string to an integer in Python

To convert, or cast, a string to an integer in Python, you use the int() built-in function.

The function takes in as a parameter the initial string you want to convert, and returns the integer equivalent of the value you passed.

The general syntax looks something like this: int(«str») .

Let’s take the following example, where there is the string version of a number:

#string version of the number 7 print("7") #check the data type with type() method print(type("7")) #output #7 #

To convert the string version of the number to the integer equivalent, you use the int() function, like so:

#convert string to int data type print(int("7")) #check the data type with type() method print(type(int("7"))) #output #7 #

A practical example of converting a string to an int

Say you want to calculate the age of a user. You do this by receiving input from them. That input will always be in string format.

So, even if they type in a number, that number will be of .

If you want to then perform mathematical operations on that input, such as subtracting that input from another number, you will get an error because you can’t carry out mathematical operations on strings.

Check out the example below to see this in action:

current_year = 2021 #ask user to input their year of birth user_birth_year_input = input("What year were you born? ") #subtract the year the user filled in from the current year user_age = current_year - user_birth_year_input print(user_age) #output #What year were you born? 1993 #Traceback (most recent call last): # File "demo.py", line 9, in # user_age = current_year - user_birth_year_input #TypeError: unsupported operand type(s) for -: 'int' and 'str' 

The error mentions that subtraction can’t be performed between an int and a string.

You can check the data type of the input by using the type() method:

current_year = 2021 #ask user to input their year of birth user_birth_year_input = input("What year were you born? ") print(type(user_birth_year_input)) #output #What year were you born? 1993 #

The way around this and to avoid errors is to convert the user input to an integer and store it inside a new variable:

current_year = 2021 #ask user to input their year of birth user_birth_year_input = input("What year were you born? ") #convert the raw user input to an int using the int() function and store in new variable user_birth_year = int(user_birth_year_input) #subtract the converted user input from the current year user_age = current_year - user_birth_year print(user_age) #output #What year were you born? 1993 #28 

Conclusion

And there you have it — you now know how to convert strings to integers in Python!

If you want to learn more about the Python programming language, freeCodeCamp has a Python Certification to get you started.

You’ll start with the fundamentals and progress to more advance topics like data structures and relational databases. In the end, you’ll build five projects to practice what you learned.

Thanks for reading and happy coding!

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