Converting list to *args when calling function
Question:
In Python, how do I convert a list to *args?
I need to know because the function
scikits.timeseries.lib.reportlib.Report.__init__(*args)
wants several time_series objects passed as *args, whereas I have a list of timeseries objects.
Answers:
You can use the * operator before an iterable to expand it within the function call. For example:
timeseries_list = [timeseries1 timeseries2 ...]
r = scikits.timeseries.lib.reportlib.Report(*timeseries_list)
(notice the * before timeseries_list)
From the python documentation:
If the syntax *expression appears in the function call, expression
must evaluate to an iterable. Elements from this iterable are treated
as if they were additional positional arguments; if there are
positional arguments x1, …, xN, and expression evaluates to a
sequence y1, …, yM, this is equivalent to a call with M+N positional
arguments x1, …, xN, y1, …, yM.
This is also covered in the python tutorial, in a section titled Unpacking argument lists, where it also shows how to do a similar thing with dictionaries for keyword arguments with the ** operator.
*args just means that the function takes a number of arguments, generally of the same type.
Check out this section in the Python tutorial for more info.
yes, using *arg passing args to a function will make python unpack the values in arg and pass it to the function.
so:
>>> def printer(*args):
print args
>>> printer(2,3,4)
(2, 3, 4)
>>> printer(*range(2, 5))
(2, 3, 4)
>>> printer(range(2, 5))
([2, 3, 4],)
>>>
In Python, how do I convert a list to *args?
I need to know because the function
scikits.timeseries.lib.reportlib.Report.__init__(*args)
wants several time_series objects passed as *args, whereas I have a list of timeseries objects.
You can use the * operator before an iterable to expand it within the function call. For example:
timeseries_list = [timeseries1 timeseries2 ...]
r = scikits.timeseries.lib.reportlib.Report(*timeseries_list)
(notice the * before timeseries_list)
From the python documentation:
If the syntax *expression appears in the function call, expression
must evaluate to an iterable. Elements from this iterable are treated
as if they were additional positional arguments; if there are
positional arguments x1, …, xN, and expression evaluates to a
sequence y1, …, yM, this is equivalent to a call with M+N positional
arguments x1, …, xN, y1, …, yM.
This is also covered in the python tutorial, in a section titled Unpacking argument lists, where it also shows how to do a similar thing with dictionaries for keyword arguments with the ** operator.
*args just means that the function takes a number of arguments, generally of the same type.
Check out this section in the Python tutorial for more info.
yes, using *arg passing args to a function will make python unpack the values in arg and pass it to the function.
so:
>>> def printer(*args):
print args
>>> printer(2,3,4)
(2, 3, 4)
>>> printer(*range(2, 5))
(2, 3, 4)
>>> printer(range(2, 5))
([2, 3, 4],)
>>>