Question

Not sure how to form corectly, but the problem is related to a shapefile(python library) function of writing a new row, which requires to write variables..
From my data I’m creating a list, which I thought I can cast to tuple and will solve my problem, but nah.. I doesn’t go so easy…

The function is asking this:
w.record(a, b, c, d....) or w.record('a', 256, 25.2444, 'd'....)
My data is in a list, but the list length is not known my default, it depends form the input data and the right length is important!

I could also write w.record(list[0], list[1]...list[len(list)-1]), but then I have to create this automatically and not sure how could I do that.

Btw, I use an old python: 2.5… (not my choise)

Answer 1

There are 4 kinds of argument in a function declaration: –

• Positional Argument
• Default Argument (or, keyword argument – in the form: – a = 5)
• Non-Keyword Argument
• Keyword Argument (or, dictionary type keyword argument)

A typical function declaration goes like this: –

func(positional_args, keyword_args,
                     *tuple_grp_nonkw_args, **dict_grp_kw_args)

You need non-keyword argument, which take extra argument and store them as tuple:

w.record(*yourvalues)

Similarly keyword argument, takes dictionary as input. They are denoted with **kwarg.

• All the keyword arguments after the non-keyword arguments go into **kwarg
• And all the keyword arguments before the non-keyword arguments are default arguments

For E.G: –

// nkwarg takes a list
// kwarg takes a dictionary
def foo(arg, defaultarg = 5, *nkwarg, **kwarg):
    print arg
    print defaultarg
    print nkwarg
    print kwarg


foo("hello", ["how", "are", "you"], a = 3, b = 4)

OUTPUT: –

hello
5
(['how', 'are', 'you'],)
{'a': 3, 'b': 4}