Beefy Boxes and Bandwidth Generously Provided by pair Networks
Keep It Simple, Stupid

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

The use of a hash in this application is positively dangerous unless the elements of the  @change array (which become the keys of the hash) can be guaranteed to be unique. E.g.:

>perl -wMstrict -le "my @change = (1.15, -0.1, 5.4, 1.03, 1.15, -0.241); my @numberofshares = (9999, 400, 200, 300, 500, 240); my %hash; @hash{@change} = @numberofshares; printf qq{%d keys in hash (oops...) \n}, scalar keys %hash; my $sum = 0; while (my($k, $v) = each %hash) { $sum += $v * $k; } print qq{sum == $sum (?)}; " 5 keys in hash (oops...) sum == 1866.16 (?)

Update: The algorithm can be expressed more concisely with some list-processing functions:

>perl -wMstrict -le "use List::Util qw(sum); use List::MoreUtils qw(pairwise); use vars qw($a $b); my @change = (1.15, -0.1, 5.4, 1.03, -0.241); my @numberofshares = ( 100, 400, 200, 300, 240); my $sum = sum pairwise { $a * $b } @change, @numberofshares; print qq{sum == $sum}; " sum == 1406.16

I think it could be expressed yet more concisely in Perl 6, but my 6-fu is not that great. Would it be something like:
    my $sum +=<<*<< @change, @numberofshares;

In reply to Re: simultaneously adding and multiplying numbers in a hash/ array by AnomalousMonk
in thread simultaneously adding and multiplying numbers in a hash/ array by derpp

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?

What's my password?
Create A New User
Domain Nodelet?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others taking refuge in the Monastery: (2)
As of 2022-08-08 17:26 GMT
Find Nodes?
    Voting Booth?

    No recent polls found