[NTG-context] Extracting a column from an array in lua

Otared Kavian otared at gmail.com
Fri Sep 20 23:00:42 CEST 2019


Hi,

Probably this is a silly question… 
In lua, I have an array named  t which is determined in a piece of lua code, having (say) two columns and I want to extract for example the first column of t and call the new array tt.
In Matlab, Scilab and friends, this can done by saying tt = t[:,1].

Is this possible in lua?
For the moment I have something like this, but I think it is not a good approach:

\starttext
\startluacode
	t = {}  -- a silly example of a matrix...
	for i = 1, 3 do
		t[i] = {}
		t[i]["columnOne"] = 10*i + 1
		t[i]["columnTwo"] = 10*i + 2
	end
	tt = {}
	for i = 1,3 do -- is it possible to avoid this ?
		tt[i] = t[i]["columnOne"]
	end
\stopluacode

The first column of the array  \type{t} is: 
\ctxlua{context.print(tt," ; ")}
\stoptext

Many thanks for any help,
Best regards: OK


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