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Adám
Adám
1:25 PM
 
 
5 hours later…
1234
1234
5:59 PM
Remove nth index column from a matrix
rm ← {(((⍵-1)∘↑⍤1)⍺ ), (⍵∘↓⍤1)⍺ }
m1
┌→────┐
↓1 2 3│
│4 5 6│
└~────┘
m1 rm 2
┌→──┐
↓1 3│
│4 6│
└~──┘
Any idea hw to shorten my rm function?
 
Adám
Adám
@1234 (Btw, press ctrl+k before posting for proper formatting)
 
1234
1234
sorry..I just forget..
 
Adám
Adám
@1234 rm←{⍺[;⍵~⍨⍳≢⍉⍺]}
Btw, this works for removing multiple columns too.
@1234 rm←{⍺/⍨⍵≠⍳≢⍉⍺} is shorter but only works for removing a single column. Amend to rm←{⍺/⍨~⍵∊⍨⍳≢⍉⍺} for removal of any number of columns.
 
1234
1234
6:19 PM
nice
 
1234
1234
6:30 PM
should APL have a primitive function to remove column or row from matrix, or higher rank array?
It seems to me it is very common operation.
 
Adám
Adám
It already has: / and ⌿
 
1234
1234
Oh
this is why I'm here.. I have no idea what I'm doing.. :)
 
Adám
Adám
The left argument is a mask indicating which columns or rows, respectively, to keep.
 
1234
1234
cool.
 

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