Add numbers row by row

epimenidecretese has asked for the wisdom of the Perl Monks concerning the following question:

I'm trying to add numbers row by row but I can't figure out how to do it.

example:

__DATA__
1   2005-01-16
6   2005-01-28
1   2005-01-31
2   2005-02-01
2   2005-02-02
1   2005-02-05
[download]

I'd like to have an output like this:

1    2005-01-16
7    2005-01-28
8    2005-01-31
10   2005-02-01
12   2005-02-02
13   2005-02-05
[download]

any tipps?

One of Crete's own prophets has said it: 'Cretans are always liars, evil brutes, lazy gluttons'.
He has surely told the truth.

Comment on Add numbers row by row Select or Download Code

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Re: Add numbers row by row by toolic (Bishop) on Oct 25, 2013 at 14:05 UTC
`use warnings; use strict; my $tot = 0; while (<DATA>) { my ($num, $date) = split; $tot += $num; printf "%-5d %s\n", $tot, $date; } __DATA__ 1 2005-01-16 6 2005-01-28 1 2005-01-31 2 2005-02-01 2 2005-02-02 1 2005-02-05` [download]	[reply] [d/l]
Re^2: Add numbers row by row by epimenidecretese (Acolyte) on Oct 25, 2013 at 14:20 UTC
Thank you very much! Works great. Where could I learn something about this string? `printf "%-5d %s\n", $tot, $date;` [download] I don't really understand what's going on. One of Crete's own prophets has said it: 'Cretans are always liars, evil brutes, lazy gluttons'. He has surely told the truth.	[reply] [d/l]
Re^3: Add numbers row by row (perldoc) by toolic (Bishop) on Oct 25, 2013 at 14:26 UTC
You're welcome. Where could I learn something about this string? In a variety of places: The "Function Nodelet", which is on the right side near the bottom of the page of my browser here at the Monastery, has a link to the printf docs. I'm not sure if this nodelet is enabled by default. The official documentation is online: printf And it is also at your command prompt: `perldoc -f printf`	[reply] [d/l]
Re^3: Add numbers row by row by LanX (Saint) on Oct 25, 2013 at 14:25 UTC
> Where could I learn something about this string? You either type "`perldoc -f`printf" or sprintf into your console ... ... or you check the online docs at http://perldoc.perl.org (but beware of the Perl version) It's also searchable per "duckduckgo: perl printf" or "google: perl printf" or other search machines... Cheers Rolf ( addicted to the Perl Programming Language)	[reply] [d/l]
Re: Add numbers row by row by davido (Cardinal) on Oct 25, 2013 at 16:31 UTC
I don't think that toolic's approach could be improved upon, but that doesn't mean we shouldn't be able to have a little fun. ;) `use feature qw(state); tally(\*DATA); sub tally { my $fh = shift; state $acc = 0; return if ! defined( local $_ = <$fh> ); $acc += ( my( $n, $d ) = split )[0]; printf "%-5d %s\n", $acc, $d; tally($fh); } __DATA__ 1 2005-01-16 6 2005-01-28 1 2005-01-31 2 2005-02-01 2 2005-02-02 1 2005-02-05` [download] One possible "improvement" to this one: Tie $n to a class that increments upon STORE, and you can eliminate `state $acc`, just using $n as the accumulator. :) Dave	[reply] [d/l] [select]