Re: help with yaml.dump

Hi,

> I'm using yaml with Python and I need to create a yaml file with
> alphabet letters and a corresponding coding.
> 
> I'd like to have an output like this:
> 
> a: 00000
> b: 00001
> ...
> 
> and so on.
> 
> I wrote this:
> 
> for i in alfabeto:
> 	yaml.dump({i : gmpy.digits(interi,2).zfill(5)}, stream)
> 
> but what I get is:
> 
> {a: '10110'}
> {b: '10110'}
> {c: '10110'}
> ...
> 
> Why does it print the parenthesis { } and apexes ' ' ?

Both

a: '10110'

and

{a: '10110'}

are valid YAML representations of the dictionary, and PyYAML is free to 
choose any of them.  However you have a limited control over the output 
style.  You could write

 >>> print yaml.dump({'a': '10100'}, default_flow_style=False)
a: '10100'

Note that you'll still get quotes around 10110.  That's because the 
object '10110' is a string, but looks like a number.  If you load the 
document

a: 10110

using PyYAML, you'll get the dictionary

{'a': 10110}

which is not equal to the original dictionary {'a': '10110'}.  Quotes 
around the value indicate that the scalar is a string and allows PyYAML 
to produce the same value it has serialized.

Regarding your original problem: perhaps you could simple write

for i in alfabeto:
     print "%s: %s" % (i, gmpy.digits(interi,2).zfill(5))

If you want to use PyYAML for this task, you'd better dump the whole 
dictionary:

print yaml.dump(dict([(i, gmpy.digits(interi,2).zfill(5))
                       for i in alfabeto]), stream)


Thanks,
Kirill

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