How To Input a List in Python?

Sometimes while coding in Python, you will need to take a list as an input. While this might sound simple at first, it is often regarded as a complex task to accomplish for a beginner. This article will tell you how to input a list in Python.

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Following pointers will be covered in this article,

• Input a List in Python
• Accept a list of number as an input in Python
• Accept a List of Strings from the User
• Examples

So let us get started then,

Input a List in Python

As you might already know, in order to accept an input from the user in Python, we can make use of the input() function. When used, it enables the programmer to accept either a string, integer or even a character as an input from the user. But when it comes to accepting a list as an input, the approach we follow is slightly different.

This how to input a List in Python article, will address main areas of concern

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Accept a list of number as an input in Python

Take a look at the example program below, which accepts a list of numbers as an input in Python.

input_string = input("Enter a list element separated by space ")
list  = input_string.split()
print("Calculating sum of element of input list")
sum = 0
for num in list:
    sum += int (num)
print("Sum = ",sum)

When the above program is run, the output will look something like this.

Output

Enter a list element separated by space 2 4 6 9

Calculating sum of element of input list

Sum =  20

Analysis

Now let us breakdown the program and see how the workings behind it.

1. As you already know, whenever we use the input() function in Python, it converts the user input into a string. Therefore in the above program, we accepted a list element from a user in the form of a string which is separated by spaces.
2. One thing to note here, is that you have the ability to accept a string separated by the operator comma (,) as well. But in this situation you need to make use of the split() function in order to pass the argument as well as the separator in the Python program.
3. If you look closely, you will find that we have made use of the function input_string.split() to split the input string separated by spaces from the user and converted them into individual elements to be added into a list.
4. We have also made use of the For loop and converted every element into an integer to calculate its sum.

Moving on to the next topic of this article let us see  how to input a list in python that holds strings,

Accept a List of Strings from the User

Similar to the above program, we have the ability to create a program in Python to accept a list of strings from the user. Take a look at the example below to understand this better.

input_string = input("Enter family members separated by comma ")
family_list  = input_string.split(",")
print("Printing all family member names")
for name in family_list:
    print(name)

When the above program is run, the output will look something like this.

Enter family members separated by comma: Julius,Mark,John

Printing all family member names

Juluis

Mark

John

Analysis

Let us breakdown the above program into pointers and understand it better.

1. Similar to the earlier example, we accepted an input list from the user in the form of a string separated by commas.
2. We have made use of the input_string.split(“,”) function to split the string separated by commas and convert it into a list of string to be used in the program.
3. We used a for loop and printed out all family names in order, as you can see in the output shared above.

Moving on let us see how this concept fares from programming perspective,

Examples

Let us take a look at a couple of other examples to understand how to input a list in Python.

Example 1

# creating an empty list
lst = []
# number of elemetns as input
n = int(input("Enter number of elements : "))
# iterating till the range
for i in range(0, n):
            ele = int(input())
            lst.append(ele) # adding the element
print(lst)

Output

Let us take a look at the next example,

Example 2

# try block to handle the exception 
try:
	my_list = [] 	
	while True: 
		my_list.append(int(input())) 		
# if input is not-integer, just print the list 
except: 
	print(my_list)

Output

Example 3

# number of elements
n = int(input("Enter number of elements : "))
# Below line read inputs from user using map() function
a = list(map(int,input("nEnter the numbers : ").strip().split()))[:n]
print("nList is - ", a)

This would be the final example of this article,

Example 4

lst = [ ]
n = int(input("Enter number of elements : "))
for i in range(0, n):
ele = [input(), int(input())]
lst.append(ele)
print(lst)

Output

This is it guys this brings us to the end of this article on  How To Input A List In Python?

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