The Most Pythonic Way to Convert a List of Tuples to a String

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Convert List of Tuples to String

The most Pythonic way to convert a list of tuples to a string is to use the built-in method str(...). If you want to customize the delimiter string, the most Pythonic way is to concatenate the join() method and the map() function '\n'.join(map(str, lst)) to convert all tuples to strings and gluing those together with the new-line delimiter '\n'.

The Most Pythonic Way to Convert a List of Tuples to a String

Exercise: Run the interactive code snippet. Which method do you like most?

Method 1: Default String Conversion

Say, you’ve got a list of tuples, and you want to convert it to a string (e.g., see this SO post). The easiest way to accomplish this is to use the default string conversion method str(...).

>>> lst = [(1,1), (2,1), (4,2)]
>>> str(lst)
'[(1, 1), (2, 1), (4, 2)]'

The result is a nicely formatted string representation of your list of tuples.

Method 2: Join() and Map()

However, if you want to customize the delimiter string, you can use the join() method in combination with the map() function:

lst = [(1,1), (2,1), (4,2)]

print('--'.join(map(str, lst)))
# (1, 1)--(2, 1)--(4, 2)

The map() function transforms each tuple into a string value, and the join() method transforms the collection of strings to a single string—using the given delimiter '--'. If you forget to transform each tuple into a string with the map() function, you’ll get a TypeError because the join() method expects a collection of strings.

Method 3: Flatten List of Tuples

If you want to flatten the list and integrate all tuple elements into a single large collection of elements, you can use a simple list comprehension statement [str(x) for t in lst for x in t].

lst = [(1,1), (2,1), (4,2)]

print('\n'.join([str(x) for t in lst for x in t]))

If you want to redefine how to print each tuple—for example, separating all tuple values by a single whitespace character—use the following method based on a combination of the join() method and the map() function with a custom lambda function lambda x: str(x[0]) + ' ' + str(x[1]) to be applied to each list element.

lst = [(1,1), (2,1), (4,2)]

print('\n'.join(map(lambda x: str(x[0]) + ' ' + str(x[1]), lst)))
1 1
2 1
4 2

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