How to send dictionary as parameter to python function

Question

Below code does not work, data is a dictionary & I was wondering how to pass it to function

def my_function(x={}):
for i , j in x:
    print (i)
    print (j)

data = {'a':1, 'b': 2, 'c': 3}
my_function(**data)

Have you tried simply passing the dictionary as an argument? my_function(data) — mkrieger1
– mkrieger1, Commented Apr 6, 2018 at 8:17
its not a good practice to have default argument value mutable! — Karnikamit
– Karnikamit, Commented Apr 6, 2018 at 8:20
@AmitKarnik it's not that it's not "good practice", but that it doesn't work as most peoples would expect docs.python-guide.org/en/latest/writing/gotchas/… — bruno desthuilliers
– bruno desthuilliers, Commented Apr 6, 2018 at 8:39

jpp · Accepted Answer · 2018-04-06 08:43:12Z

2

The below code should work for you:

def my_function(x={}):
    for i, j in x.iteritems():
        print (i)
        print (j)

data = {'a':1, 'b': 2, 'c': 3}
my_function(data)

Explanation

Ensure your indentation is correct.
To iterate a dictionary, use dict.iteritems (in Python 2.x) or dict.items (in Python 3).
If you are iterating the dictionary in this way, there is no reason to use an unpacking ** operator.
Understand the pitfalls of using Mutable Default Arguments.

answered Apr 6, 2018 at 8:13

jpp

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2 Comments

Just beware of the mutable default argument gotcha if your real function mutates it's argument (docs.python-guide.org/en/latest/writing/gotchas/…)

@brunodesthuilliers, good point - in this specific usage not an issue, but I'll add that link.