Groups > comp.lang.forth > #20163

Re: Filtering

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From	mhx@iae.nl (Marcel Hendrix)
Subject	Re: Filtering
Newsgroups	comp.lang.forth
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Date	Sat, 2 Mar 2013 11:17:16 +0200
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"WJ" <w_a_x_man@yahoo.com> writes Re: Filtering

> Given a sequence of numbers, keep those that are odd and
> multiply them by 100.

> Factor:


> USE: sequences.extras

> { 1 1 2 3 5 8 13 21 } [ odd? ] [ 100 * ] filter-map
> { 100 100 300 500 1300 2100 }


8 integer array x{   1 1 2 3 5 8 13 21 x{ #=>  
: fm ( x -- ) dup cdim 0 ?do dup i } @ dup 1 and if 100 * . else drop endif loop drop ;

x{ fm 100 100 300 500 1300 2100  ok

Or:

: fm  BEGIN  bl word dup C@  
      WHILE  count evaluate  dup 1 and IF 100 * . ELSE drop ENDIF 
      REPEAT drop ;
      
FORTH> fm  1 1 2 3 5 8 13 21  100 100 300 500 1300 2100  ok
FORTH> hex fm  1 f 2e 333 331 21fe 64 5DC 13FEC 13F24  ok
FORTH> fm  %01 %1 #10 %11 %1001 %1000 #13 $15  100 100 300 900 1300 2100  ok

-marcel

Thread

Filtering "WJ" <w_a_x_man@yahoo.com> - 2013-03-02 07:48 +0000
  Re: Filtering mhx@iae.nl (Marcel Hendrix) - 2013-03-02 11:17 +0200
  Re: Filtering "Charles Childers" <crc@retroforth.org> - 2013-03-02 11:18 -0500
    Re: Filtering "A. K." <akk@nospam.org> - 2013-03-02 17:55 +0100
      Re: Filtering Marc Olschok <nobody@nowhere.invalid> - 2013-03-03 22:11 +0000

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