Convert a list containing float numbers to string in Python

There may be situations where we want to convert a list containing float numbers to string while working in python. In this article, we will look at different ways to convert the list containing float numbers to a string which contains the elements of the list as space separated sub strings.

Important functions for the task to convert a list containing float numbers to string

To convert a list of floating point numbers to string, we will need several string methods which we will discuss first and then perform the operations.

str() function

The str() function converts an integer literal,a float literal or any other given  input to a string literal and returns the string literal of the input after conversion. This can be done as follows.

float_num=10.0
str_num=str(float_num)

join() method

join() method is invoked on a separator and an iterable object of strings is passed to the method as input. It joins each string in the iterable object with the separator and returns a new string. 

The syntax for join() method is as separator.join(iterable) where separator can be any character and iterable can be a list or tuple etc. This can be understood as follows.

str_list=["I","am","Python","String"]
print("List of strings is:")
print(str_list)
separator=" "
str_output=separator.join(str_list)
print("String output is:")
print(str_output)

Output:

List of strings is:
['I', 'am', 'Python', 'String']
String output is:
I am Python String

map() function

The map() function takes as input a function(functions are first class objects and can be passed as a parameter in python) and an iterable as argument and executes the function on each element of the iterable object and returns  the output map object which can be converted into any iterable.

The syntax for map() function is map(function,iterable). This can be understood as follows.

float_list=[10.0,11.2,11.7,12.1]
print("List of floating point numbers is:")
print(float_list)
str_list=list(map(str,float_list))
print("List of String numbers is:")
print(str_list)

Output:

List of floating point numbers is:
[10.0, 11.2, 11.7, 12.1]
List of String numbers is:
['10.0', '11.2', '11.7', '12.1']

Now we will see how to convert a list containing floating point numbers to string using the above functions.

Convert a list containing float numbers to string using for loop

We can convert the list of float numbers to string by declaring an empty string and then performing string concatenation to add the elements of the list to the string as follows.

float_list=[10.0,11.2,11.7,12.1]
print("List of floating point numbers is:")
print(float_list)
float_string=""
for num in float_list:
    float_string=float_string+str(num)+" "
    
print("Output String is:")
print(float_string.rstrip())

Output:

List of floating point numbers is:
[10.0, 11.2, 11.7, 12.1]
Output String is:
10.0 11.2 11.7 12.1

 In the above program, the output string contains an extra space at the end which has to be removed using rstrip() method.To avoid this additional operation, We can use the join() method instead of performing concatenation operation by adding the strings to create the output string as follows.

float_list=[10.0,11.2,11.7,12.1]
print("List of floating point numbers is:")
print(float_list)
float_string=""
for num in float_list:
    float_string=" ".join([float_string,str(num)])
print("Output String is:")
print(float_string.lstrip())

Output

List of floating point numbers is:
[10.0, 11.2, 11.7, 12.1]
Output String is:
10.0 11.2 11.7 12.1

In the above method, an extra space is added at left of the output string which has to be removed using lstrip() method. To avoid this,Instead of applying str() function on every element of the list, we can use map() function  to convert the list of float numbers to a list of strings and then perform the string concatenation using join() method to get the output string as follows.

float_list=[10.0,11.2,11.7,12.1]
print("List of floating point numbers is:")
print(float_list)
str_list=list(map(str,float_list))
print("List of String numbers is:")
print(str_list)
float_string=""
for num in float_list:
    float_string=" ".join(str_list)
    
print("Output String is:")
print(float_string)

Output:

List of floating point numbers is:
[10.0, 11.2, 11.7, 12.1]
List of String numbers is:
['10.0', '11.2', '11.7', '12.1']
Output String is:
10.0 11.2 11.7 12.1

Convert a list containing float numbers to string using list comprehension

Instead of for loop, we can use list comprehension to perform the conversion of a list of floating point numbers to string as follows. We can use the join() method with list comprehension as follows.

float_list=[10.0,11.2,11.7,12.1]
print("List of floating point numbers is:")
print(float_list)
str_list=[str(i) for i in float_list]
print("List of floating string numbers is:")
print(str_list)
float_string=" ".join(str_list)
print("Output String is:")
print(float_string)

Output:

List of floating point numbers is:
[10.0, 11.2, 11.7, 12.1]
List of floating string numbers is:
['10.0', '11.2', '11.7', '12.1']
Output String is:
10.0 11.2 11.7 12.1

Conclusion

In this article, we have seen how to convert a list containing floating point numbers into string using different string methods like str(), join() and for loop or list comprehension in python. Stay tuned for more informative articles.