How to convert List to String | String to List – Python Program

1. What are Lists
2. What are Strings
3. Convert List to Strings
4. Convert List of integers to a single integer
5. Convert String to Lists
6. Convert String to list of characters
7. Convert List of characters into string

What are Lists?

If you are familiar with the C programming language, then you might have heard about arrays. Lists are pretty much like arrays except that they can contain any data type, unlike arrays. A list is a collection of objects that are ordered. Also, each element in the list is indexed according to a definite sequence and the indexing of a list is done with 0 being the first index.

The list is a ‘Collection Datatype’ that can contain integers, strings, or other lists too. Lists are mutable, hence, they can be changed even after their creation. Also, note that lists can contain duplicate entries, unlike sets. Python lists can be created in the following way:

EmptyList=[] #EmptyList
listOfnumbers=[1,3,56,78] #List of numbers
listOfObjects=[1,"anything",["lists","in","lists"],2.5] # List containing different data types
print(EmptyList)
print(listOfnumbers)
print(listOfObjects)

Output:

Try Yourself. Let’s Play with Some Lists. Click Here

What are ‘Strings’?

So, what exactly are strings? Strings are one of the data types in Python and can be defined as a sequence of characters. There is a built-in class ‘str’ for handling a Python string. Creating strings is as simple as assigning a value to a variable. For example −

first_name='''Ted '''
middle_name="Evelen "#commonly used method
last_name='Mosby'#commonly used method
print(first_name,middle_name,last_name)

Output: 

Try it yourself. Let’s make some Names

As can be seen in the example above, there are three ways in which we can create a string. Although double quotes and single quotes are more often used as compared to the triple quotes, what if the string itself contains a single quote or double-quotes. Let us find out in the example below.

string_1="Hello "Python" "

string_1='Hello "Python"'
print(string_1)

string_2='Let's go to the park'

string_2="Let's go to the park"
print(string_2)

string_3='''Let's go the "PARK"'''
print(string_3)

In the above example, we learned how to avoid such errors, now moving on to the question “how to convert a list to a string?”

Convert List to String

Several methods can be used to convert a list to a string.

Method 1

By using the in-built method of python .join()

Name=["Ted","Evelen","Mosby"]
print(" ".join(Name))#used a space to separate list elements here.
Students=["Barney","Robin","Lily"]
print("\n".join(Students))

Output:

Try some Conversions Yourself

NOTE: If the list contains any non-string element, the above method does not work unless we use map() function to convert all elements to a string first. Let’s see an example:

test_list=["I","have",2,"numbers","and",8,"words","in","this","list"]
print(" ".join(map(str,test_list)))

Output:

Click here and practice 

Method 2

Using the str() method 

Numbers=[1,56,87,22.3,76]
print(str(Numbers))
#Now manipulate the str() to get string of just Numbers
print(str(Numbers)[1:-1])
#or we can use strip function to get jsy Numbers
print(str(Numbers).strip('[]'))

Output:

Try out yourself. Click here 

Method 3

Using List comprehension method

test_list=["I","have",2,"numbers","and",8,"words","in","this","list"]
listToStr = ' '.join([str(element) for element in test_list ]) 
print(listToStr) 

Output:

Click Here and Run it yourself

Convert a list of integers into a single integer

Given a list of integers like [1,2,3], Can we convert it into a single integer, 123? Sure we can.

Let’s find out some methods to do so

Method 1

Using the join() method of Python

We can use join() method along with the inbuilt method int() in Python. Let us see some examples to understand better.

list_1 = [1, 2, 3]
numbers_str = [str(i) for i in list_1] #Using list comprehension 
print(numbers_str) 
#Now that the elements have been converted to strings we can use the join method
number= int("".join(numbers_str)) #convert final string to integer
print(number) 

Output:

Try out some examples yourself. Click here

Method 2

The second method is much more naive and is best suited when we want to just display the number instead of storing it in a variable as shown in method 1. Let us see how to do this:

list_1 = [12, 15, 17] 
# iterating each element 
def toNumber(anyList):
    for i in anyList: 
        print(i, end="")
    print("")#This print statement by default prints a new line
toNumber(list_1)
toNumber([1,8,4,99])
#Note that the number is not stored anywhere.

Output:

Click Here and Practice with the above code

Convert String to List

We can use the in-built function split() to convert a string to list. Let us see some examples:

string_1="Let us convert string to list"
print(string_1.split(" "))# Here we specified " " as delimiter
#Based on the specified delimiter the list string will be sepatrated
string_2="Let*us*convert*string to*list"
print(string_2.split())#By default delimiter is space " "
print(string_2.split("*"))#Here we specified * as the  delimiter

Output:

Try out the code yourself

In the last line of output, it can be seen that the element ‘string to’ is not separated. The reason being that the delimiter specified is asterisk ‘*’ not space “ ”.

Convert String to List of characters

As discussed above, String is a sequence of characters. We can convert it to the list of characters using list() built-in function. When converting a string to a list of characters, whitespaces are also treated as characters. Also, if there are leading and trailing whitespaces, they are a part of the list elements too.

Let us see some examples:

string_1=' Great! *^& '
print(list(string_1))
print(list(string_1.strip()))

Output:

Try the code above. Click here to practice

The strip function is used to leave out all leading and trailing whitespaces but the spaces in the middle are not left out.

Convert a list of characters into a string

Converting a list of characters into a string is quite similar to converting a list of integers into a number which is already shown above. So let us see how it is done

To convert a list of characters like [g,r,e,a,t] into a single string ‘great’,we use the join() method as shown below

chars=['g','r','e','a','t']
string1=''.join(chars)
print(string1)

Output:

Click here to run it yourself

This brings us to the end of this article where we have learned how we can convert list to strings and much more. If you wish to learn more about Python and the concepts of Machine Learning, upskill with Great Learning’s PG Program in Machine Learning.

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