Python - List of float to string conversion

When working with lists of floats in Python, we may often need to convert the elements of the list from float to string format. For example, if we have a list of floating-point numbers like [1.23, 4.56, 7.89], converting them to strings allows us to perform string-specific operations or output them neatly. Let's explore different methods to perform this conversion.

Using map()

map() function provides a very efficient way to convert all elements of a list. It applies the str() function to each element of the list.

a = [1.23, 4.56, 7.89]
# Convert using map
b = list(map(str, a))
print(b)

['1.23', '4.56', '7.89']

Explanation:

• map() applies the str() function to each element of the list a.
• The result is then converted back into a list using list().
• This method is concise and efficient for large lists.

Let's explore some more ways and see how we can convert list of float to string in Python.

List Comprehension

List comprehension is a Pythonic way to iterate over the list and convert each element to a string.

a = [1.23, 4.56, 7.89]
# Convert using list comprehension
b = [str(i) for i in a]
print(b)

['1.23', '4.56', '7.89']

Explanation:

• List comprehension iterates through the list a and applies str(i) to each element.
• The result is a new list b where all float elements are converted to strings.
• This method is easy to understand and is preferred when you want more control over the conversion process.

Using for Loop

Using a for loop provides a more explicit way of converting elements in a list. This method is less concise but is useful when we want more customization.

a = [1.23, 4.56, 7.89]
# Convert using for loop
b = []
for i in a:
    b.append(str(i))
print(b)

['1.23', '4.56', '7.89']

Explanation:

• A for loop iterates through each element of the list a.
• The str(i) is applied inside the loop, and the results are appended to the new list b.

Using join() with map()

If we need to convert the list of floats to a single string where each element is separated by a specific delimiter, we can use map() along with str.join().

a = [1.23, 4.56, 7.89]
# Convert and join elements as a string
b = ', '.join(map(str, a))
print(b)

1.23, 4.56, 7.89

Explanation:

• map(str, a) converts each element of the list to a string.
• join() concatenates the string elements of the list, separating them by the delimiter , (comma and space).
• This method is useful when you want to output the list as a single formatted string.

Using numpy

If the list is a numpy array, we can use numpy.vectorize() to perform the conversion efficiently.

import numpy as np
a = np.array([1.23, 4.56, 7.89])
# Convert using numpy.vectorize
b = np.vectorize(str)(a)
print(b)

['1.23' '4.56' '7.89']

Explanation:

• numpy.vectorize() applies str() to each element in the numpy array.
• This method is efficient when working with numpy arrays, and the result is a numpy array of strings.
• This approach is mainly useful for those already working within the numpy ecosystem.