How to make string from list python

How do I convert a list into a string with spaces in Python?

How can I convert a list into a space-separated string in Python?

For example, I want to convert this list:

6 Answers 6

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You need to join with a space, not an empty string.

I’ll throw this in as an alternative just for the heck of it, even though it’s pretty much useless when compared to » «.join(my_list) for strings. For non-strings (such as an array of ints) this may be better:

For Non String list we can do like this as well

So in order to achieve a desired output, we should first know how the function works.

The syntax for join() method as described in the python documentation is as follows:

Things to be noted:

Now, to add white spaces, we just need to replace the string_name with a » » or a ‘ ‘ both of them will work and place the iterable that we want to concatenate.

So, our function will look something like this:

We need to add this:

here, the number will be a user input.

4 Ways to Convert List to String in Python

While working with python data types, there are situations when you want to convert the data collected from one type to another. There are 4 methods by which we can convert a list to a string in python with fewer lines of code. These methods of converting a list into a string include iteration, comprehension, join(), and map() method. But before understanding all these conversion methods in detail, let us understand what are lists and strings.

What is a List?

The list is one of the most important data types in the python language. A python list is an ordered and changeable collection of data objects. In Python language, the list is written as commas separated values inside the square bracket. It can also contain duplicate elements along with the negative indexing elements. The important advantage of the list is that the elements inside the list are not compulsory to be of the same data type. List undergo the operations like slicing, concentrating, etc., just like the string operations. Also, you can create a nested list, i.e., a list containing another list.

Example

Output:

What is a String?

A string is defined as a sequence of characters where a character is a simple symbol. For example, in the English Language, we have 26 characters available. The computer system does not understand characters therefore, it deals with binary numbers. Even though we can see characters on our monitor screens, internally it is stored and manipulated internally as a combination of 0’s and 1’s. In the Python programming language, a string is a sequence of Unicode characters. It s an immutable sequence data type wrapped inside single or double-quotes. That means that once you define a string, you cannot change it.

You can also assign a multi-line string to a variable using triple quotes. Many string manipulation methods are available for string data types like join(), split(), concatenation, etc. However, this method does not modify the original strings but creates a copy and modifies them accordingly.

Example

Output

Convert List to String in Python

As mentioned earlier, there are 4 methods to convert a list to string in python. Let us study them one by one in detail, along with the example and corresponding output.

1) Iterating through the List

This method will iterate every index of the input list one by one and add it to the empty string.

Example

Output:

2) Using join() method

Every element of the list will be traversed and added to the empty string. Join() method is used to concatenate all these elements and form the final output. This method will fail to work if the list contains integer elements, and therefore the output will be TypeError Exception.

Example

Output:

3) Using List Comprehension

As mentioned earlier, the join() method will fail to work if you have integer elements in your input list. But to overcome this failure, you can use the List comprehension along with join() method. List comprehension will help you to create a list of elements from the existing input list. And later uses a for loop to traverse the elements by element-wise patterns. After the traversal of elements by list comprehension, you can use the join() method to concatenate the traversed elements of the list into an empty string.

Example

Output:

4) Using map() function

map() function accepts the iterable objects such as tuples, lists, or strings. Hence, it is used to map the elements of the iterable objects with the function provided.

Example

Output:

Conclusion

List and string have their own importance as a data type in python. This article referred to python lists and strings in detail, along with different techniques and methods to convert list data types into strings. It is highly recommended to learn and understand all these methods in detail as they are very effective and efficient for converting the list to string using fewer lines of code.

Convert list to string in python using join() / reduce() / map()

In this article we will discuss different ways to convert list to string.

Convert list to string in python using join() in python

In python string class provides a function join() i.e.

join() function accepts an iterable sequence like list or tuple etc as an argument and then joins all items in this iterable sequence to create a string. In the end it returns the concatenated string.

Let’s use this join() function to convert list to string in python.

We have created a function that accepts a list and a delimiter as arguments returns a string by joining all the elements in that list,

It uses the given delimiter as separator while joining items in list. If delimiter is not provided then by default it uses a white space as delimiter. Now let’s use this function to convert a list to string,

Convert list of strings to string with space as delimiter in python

Suppose we have a list of strings,

Convert list to string by join all the strings items in the list to create a concatenated string,

As we didn’t passed any delimiter, so by default a white space character was used as separator.

Convert list to string with comma as delimiter in python

In this example, while calling the function convert_list_to_string(), we passed a comma ‘,’ as delimiter / separator, therefore it joined all the items in list using comma as separator.

Convert list to string with custom delimiter in python

We can also use any custom delimiter while converting a list to string. For example,

In this example, while calling the function convert_list_to_string(), we passed a comma ‘—‘ as delimiter / separator, therefore it joined all the items in list using ‘—-‘ as separator.

Convert list of integers to string in python using join() in python

Suppose we have a list of integers,

We want to convert this list of ints to a string by joining all the integers in list in string representation with given delimiter as separator between items. Final string should be like,

We can do using join() function, but we need to first convert list of ints to a list of strings and then we can join all the items in that list to create a string with separator. For example,

We joined all the elements by using a white space as delimiter.

Convert list of different type items to string using join() in python

We want to convert this list to a string by joining all the items in list in string representation with given delimiter as separator between items. Final string should be like,

We can do using join() function, but we need to first convert list of different type of elements to a list of strings. For that we need to call str() on each item of the list to convert it to string. Then we can join all the items in the new list of strings to create a string.

We joined all the elements by using a white space as delimiter.

Convert list to string using reduce() in python

functools module in python provides a function reduce(), which accepts a iterable sequence as argument and a function as argument. This function generates a single value from all the items in given iterable sequence. For generating the value it will, pass the first two values to given function argument and then keeps on calling the same function with result and the next argument. When it consumes all the items in sequence then the final result value will be returned.

Let’s use this to convert list to string,

Here we passed two arguments to the reduce() function,

It joined all the elements in the list to create a string, using logic provided by lambda function.

Convert list of integers to string using reduce() in python

Here we passed two arguments to the reduce() function,

It joined all the integers in the list to create a string, using logic provided by lambda function.

Convert list to string using map() in python

map() function in python accepts 2 arguments i.e. a function and an iterable sequence. Then calls the given function on each element in the sequence and returns an Iterator to iterate over the result objects.

We can use that to convert list to string i.e.

Here we passed two arguments to the map() function,

We joined all the string values returned by Iterator using join() to generate a concatenated string.

The complete example is as follows,

Output:

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How would you make a comma-separated string from a list of strings?

15 Answers 15

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This won’t work if the list contains integers

And if the list contains non-string types (such as integers, floats, bools, None) then do:

Why the map / lambda magic? Doesn’t this work?

In case if there are numbers in the list, you could use list comprehension:

or a generator expression:

«,».join(l) will not work for all cases. I’d suggest using the csv module with StringIO

Using generator expressions has the benefit of also producing an iterator but saves importing itertools. Furthermore, list comprehensions are generally preferred to map, thus, I’d expect generator expressions to be preferred to imap.

Here is a alternative solution in Python 3.0 which allows non-string list items:

the alternative solution

NOTE: The space after comma is intentional.

Don’t you just want:

Obviously it gets more complicated if you need to quote/escape commas etc in the values. In that case I would suggest looking at the csv module in the standard library:

@jmanning2k using a list comprehension has the downside of creating a new temporary list. The better solution would be using itertools.imap which returns an iterator

Here is an example with list

If you want to do the shortcut way 🙂 :

But if you want to show off with logic 🙂 :

Unless I’m missing something, ‘,’.join(foo) should do what you’re asking for.

(edit: and as jmanning2k points out,

I would say the csv library is the only sensible option here, as it was built to cope with all csv use cases such as commas in a string, etc.

It is also possible to use writer.writerows(iterable) to output multiple rows to csv.

This example is compatible with Python 3, as the other answer here used StringIO which is Python 2.

How can I convert each item in the list to string, for the purpose of joining them? [duplicate]

I need to join a list of items. Many of the items in the list are integer values returned from a function; i.e.,

How should I convert the returned result to a string in order to join it with the list?

Do I need to do the following for every integer value:

Is there a more Pythonic way to solve casting problems?

9 Answers 9

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Calling str(. ) is the Pythonic way to convert something to a string.

There’s nothing wrong with passing integers to str. One reason you might not do this is that myList is really supposed to be a list of integers e.g. it would be reasonable to sum the values in the list. In that case, do not pass your ints to str before appending them to myList. If you end up not converting to strings before appending, you can construct one big string by doing something like

The map function in python can be used. It takes two arguments. The first argument is the function which has to be used for each element of the list. The second argument is the iterable.

After converting the list into a string you can use the simple join function to combine the list into a single string

above method is the easiest and most general way to convert list into string. another short method is-

There are three ways of doing this.

let say you have a list of integers