I need to grab the first column of a list, and it's just really confusing. I've tried using hyperblocks, because I'm pretty sure it worked before, but I can't get it to work. Please help me figure it out (and maybe add an easy way to get a column of a list to the item () of block).
edit: if anyone comes across this with the same question, I just found this in the manual
I'm now realizing that that does work. I don't know why I didn't think of that, but I also want to use hyperblocks, because when dealing with large lists, they are faster.
Thanks. I would not expect it to find it there, maybe because there is another __ of__ block in the blue category, and I must have thought there's only one such block.
reasonably fast (where 3 is the column number, and of course you can put a list in that input to specify more than one column. That's more straightforward than the example in the manual that uses an empty list as the first input to ITEM.
That's a nice tutorial. I have a quibble about language: You say (LIST 1 2 3) makes a list with three rows, but "rows" really makes sense only for lists of lists. It's equally plausible to say that that's a list of one row with three items! I would just not use "row" at all in talking about one-dimensional list; use "item" instead.
Of course I wish you started with the functional blocks instead of starting with the imperative ones... And I would include an explanation about how HOFs use an empty input slot to represent each item.
COLUMNS is fast and simple, and restricted to 2D arrays. TRANSPOSE does the full APL transpose that works for any number of dimensions, so that the shape of the result is the reverse of the shape of the input.