Python: string join multiple attributes from object

Question

i have an orm based object list. i now want to concatenate some attributes delimited by the "|" (pipe) and then concatenate all objects by using "\n".

i tried:

class A(object):
    def __init__(self, name, age):
        self.name = name
        self.age = age

obj_list = [A("James", 42), A("Amy", "23")]
"\n".join("|".join(o.name, o.age for o in obj_list))

File "<console>", line 1
SyntaxError: Generator expression must be parenthesized if not sole Argument

what exactly must be parenthesized?

Any hints?

Tank you.

Here is a way just using joins: '\n'.join(['|'.join([o.name, str(o.age)]) for o in obj_list]) — Patrick Haugh
– Patrick Haugh, Commented Apr 6, 2017 at 11:39

Felix · Accepted Answer · 2017-04-06 11:45:42Z

8

I think this is what you wanted to achieve:

obj_list = [A("James", 42), A("Amy", "23")]
"\n".join("|".join((o.name, o.age)) for o in obj_list)

Result:

James|42
Amy|23

Note: if your object contains non-string attributes, you have to convert those to strings, e.g. "|".join(o.name, str(o.age)).

edited Apr 6, 2017 at 11:45

answered Apr 6, 2017 at 11:33

Felix

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6 Comments

sfr Over a year ago

Thank you. That is - for me - the second best way :) can i use a join and a inner join, so i only have to add arguments if i want to increase them or do i have to add curly braces every time too?

Felix Over a year ago

what do you mean by second best way?

Patrick Haugh Over a year ago

join is one of the times when it makes more sense to use a list comprehension in a function call. When you give it a generator expression, it has to iterate through the expression and build a list anyways. More

sfr Over a year ago

Felix, when i use your code from above i get this result TypeError: join() takes exactly one argument (2 given)

sfr Over a year ago

got that right now too :) Thank you very much! --> SOLVED

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