Test If String Contains Element from List in Python

In this article, we will learn how to check if a string contains an element from a list in python.

Methods Used

• Using Nested For Loops

• Using List Comprehension

• Using any() function

• Using the find() function

Example

Assume we have taken an input string and input list. We will now check whether the input string contains at least any one input list element.

Input

inputString = "tutorialspoint is a best learning platform for coding"
inputList = ['hello', 'tutorialspoint', 'python']

Output

YES, the string contains elements from the input list

In the above example, the input string contains 'tutorialspoint' so yes is the answer.

Method 1: Using Nested For Loops

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task -.

• Create a variable to store the input string.

• Create another variable to store the input list.

• Use the split() function(splits a string into a list. We can define the separator; the default separator is any whitespace) to split the input string into a list of words.

• Initialize a temporary flag(temp_flag) variable with 0.

• Use the for loop to traverse through the above-split words list.

• Use another nested for loop to traverse through the input list

• Use if conditional statement to check whether both elements are equal.

• Set the temp_flag with 1 if the condition is true.

• Use the break statement to break the loop if the temp_flag becomes 1.

• Use the if conditional statement to check whether the value of temp_flag is 1.

• Print the result

Example

The following program checks whether the string contains any input list element using for nested for loops -

# input string
inputString = "tutorialspoint is a best learning platform for coding"

# input list
inputList = ['hello', 'tutorialspoint', 'python']

# printing the input string
print("Input string:", inputString)

# printing input list
print("Input List:", inputList)

# splitting the input string into a list of words
wordsList = inputString.split(" ")

# temporary flag variable
temp_flag = 0

# traversing through the above-split words list
for p in wordsList:
   
   # traversing through the input list
   for q in inputList:
      
      # checking whether both the elements are equal
      if p == q:
         
         # Set the value of temp_flag by 1 if the condition is true
            temp_flag = 1
         
         # breaking from the loop if the temp_flag becomes 1
            break

# checking whether the value of temp_flag is 1
if temp_flag == 1:

   # printing "YES" if the condition is true
      print("YES, the string contains elements from the input list")
else:
   
   # else print "NO"
      print("NO, the string does not contain elements from the input list")

Output

On execution, the above program will generate the following output -

Input string: tutorialspoint is a best learning platform for coding
Input List: ['hello', 'tutorialspoint', 'python']
YES, the string contains elements from the input list

Method 2: Using List Comprehension

List Comprehension

When you wish to build a new list based on the values of an existing list, list comprehension provides a shorter/concise syntax.

bool() function ? returns the boolean value of a given object

Example

The following program checks whether the input string contains any input list element using list comprehension -

# input string
inputString = "tutorialspoint is a best learning platform for coding"

# input list
inputList = ['hello', 'tutorialspoint', 'python']

# printing the input string
print("Input string:", inputString)

# printing input list
print("Input List:", inputList)
print()

# checking whether the input string contains the list element

# using list comprehension
output = [i for i in inputList if(i in inputString)]

# printing the resulting output as boolean
print("Checking whether input string contains the list element:", bool(output))

Output

Input string: tutorialspoint is a best learning platform for coding
Input List: ['hello', 'tutorialspoint', 'python']
Checking whether input string contains the list element: True

Method 3: Using any() function

The any() function returns True if any of the items in an iterable are true, else returns False.

Syntax

any(iterable)

Example

The following program checks whether the input string contains any input list element using any() function -

# input string
inputString = "tutorialspoint is a best learning platform for coding"

# input list
inputList = ['bat', 'cat', 'dog']

# printing the input string
print("Input string:", inputString)

# printing input list
print("Input List:", inputList)
print()

# checking whether the input string contains the list element

# using any() function
output = any(k in inputString for k in inputList)
print("Checking whether input string contains the list element:", bool(output))

Output

Input string: tutorialspoint is a best learning platform for coding
Input List: ['bat', 'cat', 'dog']

Checking whether input string contains the list element: False

Method 4: Using the find() function

In this method, we are using the find() method to see if the word is present in the list; it returns -1 otherwise.

find() method

Finds the first occurrence of the given value. It returns -1 if the value is not found.

Syntax

string.find(value, start, end)

Example

The following program checks whether the input string contains any input list element using the find() function -

# input string
inputString = "tutorialspoint is a best learning platform for coding"

# input list
inputList = ['bat', 'cat', 'dog']

# printing the input string
print("Input string:", inputString)

# printing input list
print("Input List:", inputList)
print()

# Assuming the result as False initially
reslt = False

# intilializig a variable with 0
count = 0

# travsering through the input list
for item in inputList:
   
   # checking whether the current list item is found in the string
   if(inputString.find(item) != -1):
      
      # incrementing the count value by 1 if the condition is true
      count += 1
      
# checking whether the count value is greater than or equal to 1
if(count >= 1):
   
   # assign result as True if the condition is true
   reslt = True
print("Checking whether input string contains the list element:", bool(reslt))

Output

Input string: tutorialspoint is a best learning platform for coding
Input List: ['bat', 'cat', 'dog']

Checking whether input string contains the list element: False

Conclusion

In this article, we learned how to use four different methods to determine whether a string contains an element from a list. Additionally, we learned how to display the result as a boolean rather than using conditional statements.