The combination
($,)
has special code. If you remove one of the verbs from the hook, you
lose the special code.
You can use $, to do Raul's job of discarding leading axes of 1:
$ flattensingles =: (($,)~ (}.~ 1&(i.&0@:=))@$) i. 1 1 2 3
2 3
Henry Rich
On 9/4/2012 2:55 PM, Peter B. Kessler wrote:
Henry Rich wrote:
''$, ''
|length error
This one doesn't work when applied to an empty. Sometimes that's
desirable. The others work on empties.
Note that
'' ($,) A
has the same result as
'' $ , A
but the former version is backed by special code & doesn't actually do
the enfile.
Henry Rich
Does it make sense then to encapsulate this knowledge in a "firstOf" verb
firstOfHook =: '' & ($ ,) NB. Does this enfile?
B + firstOfHook A NB. Plus of B and the flatten of A.
7 9 11
? How strictly does one have to adhere to the '' ($,) A surface
syntax to avoid the enfile?
Or (because I find Hooks hard to read) as an At (or, in this case, I
could use Atop (@))
firstOfAt =: (('' & $) @: ,) NB. Does this enfile?
B + firstOfAt A NB. Plus of B and the flatten of A.
7 9 11
Either of those gives me a monad that might be useful in its own right
firstOfAt A NB. Names make things easier to read.
4
in case I was having trouble disentangling the monad on A from the dyad
with B in the original problem.
... peter
On 9/3/2012 4:00 AM, Linda Alvord wrote:
Thanks to all!
Kip Murray showed me that I am dealing with a noun that is a table
and not an atom! His solution ,A turns a list into an atom.
]A=:1 1$4
4
]C=:''
]B=:3 5 7
]B=:3 5 7
3 5 7
Two alternatives helped:
B+A
|length error
| B +A
B+{.@,A NB. Bill Lam
7 8 9
B+''$,AN NB. Henry Rich
7 8 9
B+{.,A
7 8 9
I add the third because I try to avoid @ and I create the problem
most often by using {
All work if the noun is empty.
C+{.@,A
C+''$,A
C+{.,A
So this thread really should be called: Table to Atom - First time
around.
Linda
-----Original Message-----
From: programming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Henry
Rich
Sent: Monday, September 03, 2012 1:16 AM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Scalar to Vector - Yet again
The easiest way to make a scalar of an arbitrary noun is
''($,)A
which will work on anything except an empty A.
Henry Rich
On 9/2/2012 10:52 PM, Roger Hui wrote:
You are (probably) trying to undo years of conditioning in APL, which
has the misguided "singleton extension": In APL,
2 3 4 + (?n⍴1)⍴5
worked. Singleton extension is undesirable because it complicates the
rules for the rank operator.
It feels wrong to have to do things like this every time I want to
use the result of a previous computation called A .
Alternatively, it feels wrong that A is non-scalar as computed.
On Sun, Sep 2, 2012 at 6:48 PM, Linda Alvord
<lindaalv...@verizon.net>wrote:
I finally think I know what I don't know. I want to turn "table" A
into a scalar (which it happens to look like).
A
4
$A
1 1
B=:3 5 7
A+B
|length error
| A +B
(,A)+B
|length error
| (,A) +B
(,3$A)+B
7 9 11
(,($B)$A)+B
7 9 11
It feels wrong to have to do things like this every time I want to
use the result of a previous computation called A .
Linda
-----Original Message-----
From: programming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Linda
Alvord
Sent: Saturday, September 01, 2012 7:26 PM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Scalar to Vector - Yet again
I wasn't thinking. A isn't a scalar. I even knew it had shape 1 1 .
A
4
$A
1 1
$3 2
2
2$A
4
4
3 2 + ,2$A
7 6
This works! Thanks.
Linda
-----Original Message-----
From: programming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] On Behalf Of km
Sent: Saturday, September 01, 2012 6:10 PM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Scalar to Vector - Yet again
,4 is a vector
Sent from my iPad
On Sep 1, 2012, at 4:56 PM, "Linda Alvord" <lindaalv...@verizon.net>
wrote:
I vow to remember how to do this, and several months later I forget
and can't find it
anywhere. Is there some way to get to the example from the
vocabulary
page?
Maybe I can remember that.
A=:1 1$4
3 2 + A
|length error
| 3 2 +A
Thanks.
Linda
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