Does matrix-map-cols do what you want? It's the last function on page
Also, welcome to Racket!
On Mon, Oct 17, 2016 at 7:00 PM, Pierre-Henry Frohring <
> First time here, and just a few hours into Racket...
> It is not going to be rocket science ;-).
> I am using Emacs and org-mode to map each heading of an org file to a
> html file.
> Result: one org file → one static website.
> The org file contains data that is exported to a tsv file:
> A code block in the org file is evaluated:
> And produces a stacked-chart from the tsv data:
> The tsv data is parsed into a kind of matrix `M` where each cell `M[i][j]`
> is a
> ex: `M[i]` is the column "day" i.e. contains dates
> `M[i]` is the column "description" i.e. contains strings
> In order to use operations over "day" column (adding dates, ...) it is
> needed to
> parse that column with something like: `iso8601->date` but not the
> So, it is needed to apply a vector of functions `vF = [f_0,f_1,...]` to `M
> [col_0,col_1,...]` such that: `(matrix-apply vF M) = M'` where:
> M' = [f_0(col_0),f_1(col_1),...,f_n(col_n)]
> Well, this function `matrix-apply` does not seem to exist and my attempt at
> implementing it feels clunky to say the least (ex: fs is not a vector):
> (define (matrix-apply fs m)
> (cond [(= (length fs) (matrix-num-cols m))
> (map (λ (f_col)
> (λ (mat) (matrix-map (car f_col) mat))
> (cdr f_col)))
> (matrix-cols m2))))]
> [#t (error fs)]))
> (define m2 (matrix [[1 2 3 4]
> [1 2 3 4]]))
> (matrix-apply (list sqr sqr sqr sqr) m2)
> => (array #[#[1 4 9 16] #[1 4 9 16]])
> Am I missing the elephant in the corridor? Is an implementation floating
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