charts.lines: add scale

diff --git a/lines/lines-tests.factor b/lines/lines-tests.factor
index d548eab50634d1f496b544c65dcbaf6941aaeeef..24301d318766aa4f6cd64ac9a7e5e6adf11c7815 100644 (file)
--- a/lines/lines-tests.factor
+++ b/lines/lines-tests.factor
@@ -1,6 +1,6 @@
 ! Copyright (C) 2017 Alexander Ilin.
 
-USING: kernel sequences tools.test charts.lines
+USING: kernel math sequences tools.test charts.lines
 charts.lines.private ;
 IN: charts.lines.tests
 
@@ -231,6 +231,12 @@ IN: charts.lines.tests
     { 0 300 } flip-y-axis
 ] unit-test
 
+{
+    { 0 30 60 90 120 150 180 210 240 270 300 }
+} [
+    11 iota [ 10 + ] map [ 300 swap 20 10 scale ] map
+] unit-test
+
 { { } }
 [ { } { } clip-data ] unit-test
 

diff --git a/lines/lines.factor b/lines/lines.factor
index 4b885c142c703db59b6c622290098cdf73a5d230..79d9e8bfba73928881748deb462a2055308b0616 100644 (file)
--- a/lines/lines.factor
+++ b/lines/lines.factor
@@ -211,6 +211,9 @@ SYMBOL: elt
 : flip-y-axis ( chunks ymin,ymax -- chunks )
     first2 middle 2 * '[ [ first2 _ swap - 2array ] map ] map ;
 
+! value' = (value - min) / (max - min) * width
+: scale ( width value max min -- value' ) neg [ + ] curry bi@ / * ;
+
 PRIVATE>
 
 : draw-line ( seq -- )