hofer wrote:
Let's take following perl code snippet:
%myhash=( one => 1 , two => 2 , three => 3 );
($v1,$v2,$v3) = @myhash{qw(one two two)}; # <-- line of interest
print "$v1\n$v2\n$v2\n";
How do I translate the second line in a similiar compact way to
python?
Below is what I tried. I'm just interested in something more compact.
Python does not try to be as compact as Perl. Pythoneers generally
consider that a feature. Anyway, the second Python version is
asymtotically as compact as the Perl code, differing only by a small
constant number of bytes while the code size grows.
mydict={ 'one' : 1 , 'two' : 2 , 'three' : 3 }
# first idea, but still a little too much to type
[v1,v2,v3] = [ mydict[k] for k in ['one','two','two']]
The initial brackets add nothing. "v1,v2,v3 =" does the same.
# for long lists lazier typing,but more computational intensive
# as split will probably be performed at runtime and not compilation
time
You have spent and will spend more time posting and reading than the
equivalent extra computation time this will take with any normal
exchange rate and computation usage.
[v1,v2,v3] = [ mydict[k] for k in 'one two two'.split()]
This is a standard idiom for such things. If it bothers you, type "'one
two two'.split()" into an interactive window and 'in a blink' get
['one', 'two', 'two'], which you can cut and paste into a program.
print "%s\n%s\n%s" %(v1,v2,v3)
However, more that about 3 numbered variables in a Python program
suggest the possibility of a better design, such as leaving the values
in a list vee and accessing them by indexing.
Terry Jan Reedy
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