/Et tu, R. E.?/
Using $. for this is using a sledgehammer to crack an egg.
Henry Rich
On 11/13/2020 3:00 PM, R.E. Boss wrote:
$.$.M
0 0 │ 1
0 1 │ 2
0 2 │ 3
0 3 │ 4
1 0 │ 5
1 1 │ 6
1 2 │ 7
1 3 │ 8
2 0 │ 9
2 1 │ 10
2 2 │ 11
2 3 │ 12
R.E. Boss
-----Original Message-----
From: Programming <[email protected]> On Behalf Of
thomas.bulka via Programming
Sent: vrijdag 13 november 2020 18:05
To: [email protected]
Subject: [Jprogramming] Getting indices of matrix elements
Hi everyone,
still learning J, I stumbled across a problem which should be easy to solve,
but somehow I have not been able to do so, yet. Say, I have defined a matrix M:
M =: 3 4 $ >: i. 12
I now want to get the row and column index of 6 in M, which is 1 2. If M was a
vector, I could easily get the index of 6 with the help of I.:
I. 6 = , M
Applying I. to M in its original shape, however, returns a boolean vector which
indicates in which rows 6 has been found (at least that is my interpretation).
Is it possible to apply I. to higher rank arrays in order to receive the
complete indices of the elements I'm looking for? Or should I approach that
problem in another way?
Thank you very much in advance for your help!
Kind regards,
Thomas
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