Re: [NTG-context] Axis macro in MetaFun

11 Sep 2021

      On 9/11/2021 4:27 PM, kauśika cittūr via ntg-context wrote:
...
Dear All,
I am truly grateful for the new additions to MetaFun. It has greatly helped me
in producing neat drawings for my academic work. In this connection, I have a
few queries.
Currently I am using PGFPlots (with ConTeXt) to draw simple plots from CSV
data. I was wondering if there is any way to do the same in MetaFuns. That is,
is it possible to do something like the following in order to obtain a line
plot of the values in the 'data.csv' file? Also is it possible to have the
'labels' be the identical for all points in a given list?
\startMPcode
   draw lmt_axis [
       sx = 2mm, sy = 2mm,
       nx = 80, ny = 40,
       tx = 15, ty = 15,
list = {
             [
                   connect = true,
                   color = "darkblue",
                   close = true,
                   points = {data.csv},
                   labels = {"•"},
             ]
       },
   ] withpen pencircle scaled 0.5mm;
\stopMPcode
It depends on how one has data in the csv, You can patch mlib-scn.lmt 
(line 659)

     if type(v) == "table" then
         return injectpath(v,connector,close)
     elseif type(v) == "string" then
         local code = load("return " .. v)
         if code then
             return code()
         end
     else
         return injectpair(0,0)
     end

then a string represents a function:

\starttext

\startluacode
     io.savedata("temp.csv", "x,y\n10,10\n20,40\n30,30\n")

     local mycsvsplitter = utilities.parsers.rfc4180splitter()

     function MP.MyPoints(name)
         local data = io.loaddata(name)
         local list = mycsvsplitter(data)
         table.remove(list,1)
         for i=1,#list do
             list[i][1] = tonumber(list[i][1])
             list[i][2] = tonumber(list[i][2])
         end
         mp.inject.path(list)
     end

\stopluacode

\startMPcode
   draw lmt_axis [
       sx = 2mm, sy = 2mm,
       nx = 80, ny = 40,
       tx = 15, ty = 15,

       list = {
             [
                   connect = true,
                   color = "darkblue",
                   close = true,
                   points = "MP.MyPoints('temp.csv')",
                   labels = {"•"},
             ]
       },
   ] withpen pencircle scaled 0.5mm;
\stopMPcode

\stoptext

we can of course have some predefined and when we can agree on how these 
files loo, adding a "csv" is no big deal ... it's all about consistent 
interfacing

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