Print Page - Get a frame of lines from a table by filter

Title: Get a frame of lines from a table by filter
Post by: lyl on April 20, 2019, 05:41:53 PM

I have a table like this:

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(setq lst '(("header1" "header2" "header3") ( "11" "12" "13") ("21" "22" "23") ("31" "32" "33") ("41" "42" "43" )))

I want to get some continueous lines e.g. from the first line to the third line by this:

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(filter (and (>= $idx 1) (<= $idx 3)) lst)  ;; '(( "11" "12" "13") ("21" "22" "23") ("31" "32" "33") ) wanted.

But I find the function "filter" does not support "$idx".

So, is there a better way to achieve this?

Title: Re: Get a frame of lines from a table by filter
Post by: Lutz on April 21, 2019, 05:08:46 AM

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> (slice lst 1 3)
(("11" "12" "13") ("21" "22" "23") ("31" "32" "33"))
>

http://www.newlisp.org/downloads/newlisp_manual.html#slice

Or shorter:

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> (1 3 lst)
(("11" "12" "13") ("21" "22" "23") ("31" "32" "33"))

See here:

http://www.newlisp.org/downloads/newlisp_manual.html#implicit_rest_slice

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