On 12/28/2017 6:36 PM, Jorge Manuel wrote:

When I need to draw datapoints from a external data file I’m using lua, like this:

\starttext

\startluacode

Elemento = {} x = {} y ={} z= {} carga = {} i=1 context("\\startMPcode”)

context("numeric u; u := 1.5cm;") for line in io.lines("molecule.xyz http://molecule.xyz") do    local a, b, c, d, e = string.match(line, '(%a+)%s*%s*(%S+)%s*%s*(%S+)%s*%s*(%S+)%s*%s*(%S+)')    Elemento[i]= a    x[i]= tonumber(b)    y[i]= tonumber(c)    z[i]= tonumber(d)    carga[i]= tonumber(e)

   context("label(\"%s\", (%0.6f u, %0.6f u));", a, x[i],y[i])

   i=i+1 end

context("\\stopMPcode”)

\stopluacode

\stoptext

*Is there a way to pass directly the external data to MetaPost without using Lua?*

I know that I can use a similar function to gdata from graph.mp. I try to reuse this piece of code, but not works.

\startMPcode

vardef Grdln_@#(expr f) =   save n_, s_; string s_;   s_ = readfrom f;   string @#[];   if s_<>EOF:     @#1 := loptok s_;     n_ = if @#1="%": 0 else: 1 fi;     forever:       @#[incr n_] := loptok s_;       exitif @#[n_]="  ";     endfor     @#1<>"  "   else: false   fi enddef;

Grdln_$("molecule.xyz http://molecule.xyz");

\stopMPcode mp file handling is rather crippled so this is where lua is better

\starttext \startluacode MP.mycode = { } local elements = { } function MP.mycode.loadelements(filename) elements = { } for line in io.lines(filename) do elements[#elements+1] = { string.match(line, '(%S+)%s*(%S+)%s*(%S+)%s*(%S+)%s*(%S+)') } end end function MP.mycode.nofelements() mp.print(#elements) end function MP.mycode.getlabel(i) mp.quoted(elements[i][1]) end function MP.mycode.getoffset(i) mp.pair(elements[i][2],elements[i][3]) end \stopluacode \startMPcode lua.MP.mycode.loadelements("molecule.xyz") ; for i=1 upto lua.MP.mycode.nofelements() : label (lua.MP.mycode.getlabel(i),50 * lua.MP.mycode.getoffset(i)) ; endfor ; \stopMPcode \startMPcode def my_loadelements(expr name) = lua.MP.mycode.loadelements(name) ; enddef ; vardef my_nofelements = lua.MP.mycode.nofelements() enddef ; vardef my_label(expr i) = lua.MP.mycode.getlabel(i) enddef ; vardef my_offset(expr i) = lua.MP.mycode.getoffset(i) enddef ; my_loadelements("molecule.xyz") ; for i=1 upto my_nofelements : label (my_label(i),50 * my_offset(i)) ; endfor ; \stopMPcode \stoptext If you use that kind of code a lot you can hide the lua calls in macros which makes it look like metapost does it all. Hans ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -----------------------------------------------------------------