Re: [NTG-context] bar graphs, m-graph, sarith

8 Jul 2013


      Thank you Alan. That was exactly the redirection needed.

John

On Jul 7, 2013, at 9:24 AM, Alan BRASLAU wrote:
...
Metapost now has double precision arithmetic, so one no longer needs to
use the string arithmetic macros. However, it may be necessary to use
scantokens as in
clearxy;
z = (scantokens v1, scantokens v2);
augment.p(x,0);
augment.p(x,y);
x := x + 0.4 ;
augment.p(x,y);
augment.p(x,0);
Alan
On Sat, 6 Jul 2013 22:01:06 -0400
John Kitzmiller  wrote:
...
When trying to make a bar graph with m-graph.mkiv and sarith, the
command Ssub (string subtract) seems to augment.p(v1 Sadd
"0.4",v2);Sadd instead. An mwe of a bar graph:
(data1 is a separate file containing
 01 02
 02 03)
\usemodule[m-graph]
\startMPpage[instance=graph]
input sarith;
draw begingraph(5cm,5cm);
gdata("data1", v,
         path p;
         augment.p(v1,0);
         augment.p(v1,v2)
         augment.p(v1 Sadd "0.4",v2);
         augment.p(v1 Sadd "0.4",0);
         gfill p--cycle withcolor .8white;
         gdraw p--cycle;
         );
endgraph;
\stopMPpage
...which gives bars of width 0.4 starting at abscissa 1 and 2 as
expected. To increase the width of the bars to 0.8 and have them
centered over 1 and 2, I expect to Ssub from the first two augments:
\usemodule[m-graph]
\startMPpage[instance=graph]
input sarith;
draw begingraph(5cm,5cm);
gdata("data1", v,
         path p;
         augment.p(v1 Ssub "0.4",0);
         augment.p(v1 Ssub "0.4",v2);
         augment.p(v1 Sadd "0.4",v2);
         augment.p(v1 Sadd "0.4",0);
         gfill p--cycle withcolor .8white;
         gdraw p--cycle;
         );
endgraph;
\stopMPpage
However, the Ssub adds instead and gives a line at 1.4 and 2.4.
Compiling the above with mpost or mptopdf gives the desired
result(s), but I am curious if this can be resolved so such bar
graphs could be made within ConTeXT/METAFUN.
Thanks! John