REQ: Small Perl to Python conversion needed
Howdie Python folks! I am very new to Python ( 3rd day now ) and it has
already earned its place as my fav. language to work in. I hope to
continue, and I really would appreciate some good resources if anybody
would care to contribute.
My current head-scratcher concerns something I can do in Perl which I
would like to have duplicated for Python. I have noticed that it is not
possible to increment an unset value in Python, so I would like to know
how to duplicate the following bit of code using Python dictionaries.
#!/usr/bin/perl
# Parse comma delimited lines and create a final frequency hash
# Real example would read a file line by line
my %dict = {};
my @lines = ( 1,2,3,4,5, 2,3,4,5, 3,4,5, 4,5, 5 );
foreach(@lines) { map( $dict{ $_ }++, split( , ) ); }
foreach( sort byKeys keys %dict ) {
print Key: $_\tFrequency: , * x $dict{ $_ }, \n
if $dict{ $_ } =~ /\d+/g;
}
sub byKeys { $dict{$b} = $dict{$a} }
__DATA__
Results:
Key: 5 Frequency: *
Key: 4 Frequency:
Key: 3 Frequency: ***
Key: 2 Frequency: **
Key: 1 Frequency: *
--
Koncept
The snake that cannot shed its skin perishes. So do the spirits who are
prevented from changing their opinions; they cease to be a spirit. -Nietzsche
--
http://mail.python.org/mailman/listinfo/python-list
Re: REQ: Small Perl to Python conversion needed
Koncept wrote:
#!/usr/bin/perl
# Parse comma delimited lines and create a final frequency hash
# Real example would read a file line by line
my %dict = {};
my @lines = ( 1,2,3,4,5, 2,3,4,5, 3,4,5, 4,5, 5 );
foreach(@lines) { map( $dict{ $_ }++, split( , ) ); }
foreach( sort byKeys keys %dict ) {
print Key: $_\tFrequency: , * x $dict{ $_ }, \n
if $dict{ $_ } =~ /\d+/g;
}
sub byKeys { $dict{$b} = $dict{$a} }
__DATA__
Results:
Key: 5 Frequency: *
Key: 4 Frequency:
Key: 3 Frequency: ***
Key: 2 Frequency: **
Key: 1 Frequency: *
I don't speak Perl, but based on your output, I'd probably do something
like:
py lines = [1,2,3,4,5, 2,3,4,5, 3,4,5, 4,5, 5]
py counts = {}
py for items in lines:
...for item in items.split(','):
...counts[item] = counts.get(item, 0) + 1
...
py for key in sorted(counts, key=counts.__getitem__, reverse=True):
... print 'Key: %s Frequency: %s' % (key, '*'*counts[key])
...
Key: 5 Frequency: *
Key: 4 Frequency:
Key: 3 Frequency: ***
Key: 2 Frequency: **
Key: 1 Frequency: *
I'm probably missing a few subtleties, but hopefully this will get you
started.
STeVe
--
http://mail.python.org/mailman/listinfo/python-list
Re: REQ: Small Perl to Python conversion needed
Koncept wrote:
Howdie Python folks! I am very new to Python ( 3rd day now ) and it has
already earned its place as my fav. language to work in. I hope to
continue, and I really would appreciate some good resources if anybody
would care to contribute.
My current head-scratcher concerns something I can do in Perl which I
would like to have duplicated for Python. I have noticed that it is not
possible to increment an unset value in Python, so I would like to know
how to duplicate the following bit of code using Python dictionaries.
[expletives deleted]
freq_dict = {}
...
if thing in freq_dict:
freq_dict[thing] += 1
else:
freq_dict[thing] = 1
or, less plainly,
freq_dict[thing] = freq_dict.get(thing, 0) + 1
--
http://mail.python.org/mailman/listinfo/python-list
Re: REQ: Small Perl to Python conversion needed
Hi All-- John Machin wrote: how to duplicate the following bit of code using Python dictionaries. [expletives deleted] +1 QOTW Metta, Ivan -- Ivan Van Laningham God N Locomotive Works http://www.andi-holmes.com/ http://www.foretec.com/python/workshops/1998-11/proceedings.html Army Signal Corps: Cu Chi, Class of '70 Author: Teach Yourself Python in 24 Hours -- http://mail.python.org/mailman/listinfo/python-list
Re: REQ: Small Perl to Python conversion needed
John Machin wrote:
freq_dict = {}
...
if thing in freq_dict:
freq_dict[thing] += 1
else:
freq_dict[thing] = 1
or, less plainly,
freq_dict[thing] = freq_dict.get(thing, 0) + 1
or
try:
freq_dict[thing] += 1
except KeyError:
freq_dict[thing] = 1
STeVe
--
http://mail.python.org/mailman/listinfo/python-list
Re: REQ: Small Perl to Python conversion needed
In article [EMAIL PROTECTED], Steven Bethard
[EMAIL PROTECTED] wrote:
I don't speak Perl, but based on your output, I'd probably do something
like:
py lines = [1,2,3,4,5, 2,3,4,5, 3,4,5, 4,5, 5]
py counts = {}
py for items in lines:
...for item in items.split(','):
...counts[item] = counts.get(item, 0) + 1
...
py for key in sorted(counts, key=counts.__getitem__, reverse=True):
... print 'Key: %s Frequency: %s' % (key, '*'*counts[key])
...
Key: 5 Frequency: *
Key: 4 Frequency:
Key: 3 Frequency: ***
Key: 2 Frequency: **
Key: 1 Frequency: *
I'm probably missing a few subtleties, but hopefully this will get you
started.
STeVe
Thanks Steven. This helped a lot. Exactly what I was looking for
--
Koncept
The snake that cannot shed its skin perishes. So do the spirits who are
prevented from changing their opinions; they cease to be a spirit. -Nietzsche
--
http://mail.python.org/mailman/listinfo/python-list
