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I'm using J in my work, and I've got an array selection problem I don't
see the answer to. All my experiments are at work, but I'll try to
recreate something similar.
I've got a rank 3 array (report) that I've pulled in from an Excel
workbook. Each of the tables has some number of rows and a fixed number
of columns. I've matched the data to determine how many rows I want to
look at in each table; now I'd like to create a rank 2 or perhaps rank 3
table (depending upon the need) that selects all the valid data in
certain rows on certain items.
That is, if
]a=: i. 3 4 5
0 1 2 3 4
5 6 7 8 9
10 11 12 13 14
15 16 17 18 19
20 21 22 23 24
25 26 27 28 29
30 31 32 33 34
35 36 37 38 39
40 41 42 43 44
45 46 47 48 49
50 51 52 53 54
55 56 57 58 59
then I might want
2 7 12 0
22 27 0 0
42 47 52 57
I know the numbers of the first row to drop (3 2 5 in that example) and
the row I want (2 in that example); can you help me craft the argument
to { to generate that?
I'm content with zeros padding the remainder of the table, but I'll also
take a boxed result with just the right number of entries in each box.
Thanks,
Bill
- --
Bill Harris http://facilitatedsystems.com/weblog/
Facilitated Systems Everett, WA 98208 USA
http://facilitatedsystems.com/ phone: +1 425 337-5541
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