Given a list of tuples, return a string by concatenation

Question

def display(xs):
    string1 = ''
    for i in range(len(xs)):
        string1+=str(xs[i])+'-'
    return string1

Given a list of tuples as xs = [(2,3),(4,4),(5,5),(6,6)].Return this list as a string, by adding them up with dashes '-'.

So I wan to return a string that looks something like '(2,3)-(4,4)-(5,5)-(6,6)'.

What my code does is it correctly adds the dashes but the errors I am getting is that is doesn't read in the first value and it also ends up with an extra dash at the end.

My code returns a string that looks like '(4,4)-(5,5)-(6,6)-' which is wrong. I have shown my code above and need help fixing this.

Possible duplicate of [Convert a list of characters into a string](http://stackoverflow.com/questions/4481724/convert-a-list-of-characters-into-a-string) — Colonel Beauvel, Apr 30 '16 at 19:01
When testing your code it does "read" the first tuple correctly. By the way, using `for i in range(len(xs))` and then `xs[i]` is redundant. Instead, simply do `for tup in xs`. — DeepSpace, Apr 30 '16 at 19:01

Ozgur Vatansever · Accepted Answer · 2016-04-30T19:07:37.620

You are on the right track. However, it'd be better to use .join() in this case to not append - to the last tuple in the list:

>>> def display(xs):
...    return "-".join(map(str, xs))

>>> display([(2,3),(4,4),(5,5),(6,6)])
'(2, 3)-(4, 4)-(5, 5)-(6, 6)'

If you don't want the whitespace between tuple items, you gotta format them yourself:

>>> def display(xs):
...     return "-".join("({},{})".format(*t) for t in xs)

>>> display([(2,3),(4,4),(5,5),(6,6)])
'(2,3)-(4,4)-(5,5)-(6,6)'

Here is the modified version of your function:

>>> def display(xs):
...     string1 = ""
...     for i in range(len(xs)):
...         string1 += str(xs[i])
...         if i != len(xs) - 1:
...             string1 += "-"
...     return string1

Given a list of tuples, return a string by concatenation

1 Answers1