testfld (0{j_index)} table NB. put new contents into
This line doesn't do jack. m} creates a new table, modified
as requested. But you don't do anything with the new table, so it
is quietly discarded. You meant
table =. testfld (<j_index,0)} table
where
<row,col
or
<row;col
is how you index an individual cell.
The loop could be replaced by
table =. (<"0 i. #table) (<a:;0)} table
Interesting exercise: why did your erroneous verb produce the result it did?
Henry Rich
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Hahn, Harvey
> Sent: Wednesday, July 30, 2008 4:06 PM
> To: Programming forum
> Subject: [Jprogramming] Amending within a For loop
>
> I have read and re-read the "Amend" and "For" dictionary
> entries as well as the "For" entries in the Rich and Stokes
> online books, and I have tried a couple of experimental
> variations with no luck. Here's a simplified example of the
> problem I'm having:
>
> test=: 3 : 0
> table=. 4 3 $
> 'aaa';'aa';'a';'bbb';'bb';'b';'ccc';'cc';'c';'ddd';'dd';'d'
> numrows=. 0{$table
> for_j. (i. numrows) do.
> testfld=. < j_index NB. create arbitrary new field contents
> testfld (0{j_index)} table NB. put new contents into
> first cell in row
> end.
> )
>
> test''
> +---+--+-+
> |aaa|aa|a|
> +---+--+-+
> |bbb|bb|b|
> +---+--+-+
> |ccc|cc|c|
> +---+--+-+
> |3 |3 |3│
> +---+--+-+
>
> Why do I get the above table instead of the intended table below?
>
> +-+--+-+
> |0|aa|a|
> +-+--+-+
> |1|bb|b|
> +-+--+-+
> |2|cc|c|
> +-+--+-+
> |3|dd|d│
> +-+--+-+
>
> What am I missing about the "Amend" and/or "For" commands?
> Thanks in advance for your guidance!
>
> Harvey
>
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