Lazy scatterplot for Vector & Table

app/gui/view/graph-editor/src/builtin/visualization/java_script/scatterPlot.js

@@ -49,7 +49,9 @@ class ScatterPlot extends Visualization {
 
     constructor(data) {
         super(data)
-        this.setPreprocessor('process_to_json_text', 'Standard.Visualization.Scatter_Plot')
+        this.bounds = null
+        this.limit = 32
+        this.updatePreprocessor()
         this.dataPoints = []
         this.axis = {
             x: { scale: LINEAR_SCALE },
@@ -58,6 +60,14 @@ class ScatterPlot extends Visualization {
         this.points = { labels: VISIBLE_POINTS }
     }
 
+    updatePreprocessor() {
+        let fn = 'x -> process_to_json_text x limit=' + this.limit
+        if (this.bounds) {
+            fn += ' bounds=[' + this.bounds.join(',') + ']'
+        }
+        this.setPreprocessor(fn, 'Standard.Visualization.Scatter_Plot')
+    }
+
     /**
      * Presents a scatterplot visualization after receiving `data`.
      */
@@ -377,6 +387,9 @@ class ScatterPlot extends Visualization {
             let yMin = zoom.transformedScale.yScale.invert(extent[1][1])
             let yMax = zoom.transformedScale.yScale.invert(extent[0][1])
 
+            this.bounds = [xMin, yMin, xMax, yMax]
+            this.updatePreprocessor()
+
             zoom.transformedScale.xScale.domain([xMin, xMax])
             zoom.transformedScale.yScale.domain([yMin, yMax])
 
@@ -726,7 +739,7 @@ class ScatterPlot extends Visualization {
         addStyleToElem(
             'button',
             `
-            margin-left: 5px; 
+            margin-left: 5px;
             margin-bottom: 5px;
             display: inline-block;
             padding: 2px 10px;
@@ -806,6 +819,10 @@ class ScatterPlot extends Visualization {
             zoom.transformedScale.yScale.domain(domainY)
 
             self.zoomingHelper(zoom.transformedScale, boxWidth, scatter, points)
+
+            self.bounds = null
+            self.limit = 32
+            self.updatePreprocessor();
         }
 
         document.addEventListener('keydown', e => {

distribution/lib/Standard/Visualization/0.0.0-dev/src/Scatter_Plot.enso

@@ -3,6 +3,7 @@ from Standard.Base import all
 import Standard.Table.Data.Column
 import Standard.Table.Data.Table
 import Standard.Visualization.Helpers
+from Standard.Base.Data.Index_Sub_Range import Sample
 
 ## PRIVATE
 
@@ -132,10 +133,26 @@ Table.Table.axes self =
     if axes_obj.fields.size > 0 then axes_obj else Nothing
 
 ## PRIVATE
-Vector.Vector.point_data : Vector -> Object
-Vector.Vector.point_data self =
-        self.map_with_index <| i-> elem->
-            Json.from_pairs [[X.name,i],[Y.name,elem]]
+Vector.Vector.point_data : Vector -> [Int]|Nothing -> Int|Nothing-> Object
+Vector.Vector.point_data self bounds limit =
+    data = case bounds of
+        Nothing ->
+            self.map_with_index <| i-> elem->
+                Json.from_pairs [[X.name,i],[Y.name,elem]]
+        _ ->
+            minX = bounds.at 0
+            minY = bounds.at 1
+            maxX = bounds.at 2
+            maxY = bounds.at 3
+            pairs = self.map_with_index <| i-> elem->
+                if minX>i || i>maxX || minY>elem || elem>maxY then Nothing else
+                    Json.from_pairs [[X.name,i],[Y.name,elem]]
+            pairs.filter case _ of
+                Nothing -> False
+                _ -> True
+    case limit of
+        Nothing -> data
+        n -> data.take (Sample n)
 
 ## PRIVATE
 json_from_table : Table -> Json
@@ -146,8 +163,8 @@ json_from_table table =
 
 ## PRIVATE
 json_from_vector : Vector Any -> Json
-json_from_vector vec =
-    data = [data_field, vec.point_data]
+json_from_vector vec bounds=Nothing limit=Nothing =
+    data = [data_field, vec.point_data bounds limit]
     axes = [axis_field, Nothing]
     Json.from_pairs [data, axes]
 
@@ -160,11 +177,11 @@ json_from_vector vec =
    Arguments:
    - value: the value to be visualized.
 process_to_json_text : Any -> Text
-process_to_json_text value =
+process_to_json_text value bounds=Nothing limit=Nothing =
     json = case value of
         Column.Column _ -> json_from_table  value.to_table
         Table.Table _   -> json_from_table  value
-        Vector.Vector _ -> json_from_vector value
+        Vector.Vector _ -> json_from_vector value bounds=bounds limit=limit
         _               -> json_from_vector value.to_vector
 
     json.to_text

test/Visualization_Tests/src/Scatter_Plot_Spec.enso

@@ -10,8 +10,7 @@ import Standard.Test
 import project
 
 spec =
-    expect value axis_expected_text data_expected_text =
-        text = Scatter_Plot.process_to_json_text value
+    expect_text text axis_expected_text data_expected_text =
         json = Json.parse text
         json.fields.keys.should_equal ['axis','data']
 
@@ -20,6 +19,10 @@ spec =
         expected_result        = Json.from_pairs [expected_axis_labels, expected_data_pair]
         json.should_equal expected_result
 
+    expect value axis_expected_text data_expected_text =
+        text = Scatter_Plot.process_to_json_text value
+        expect_text text axis_expected_text data_expected_text
+
     index = Scatter_Plot.index_name
     axis label = Json.from_pairs [['label',label]]
     labels x y = Json.from_pairs [['x', axis x], ['y', axis y]] . to_text
@@ -96,6 +99,20 @@ spec =
             vector = [0,10,20]
             expect vector no_labels '[{"x":0,"y":0},{"x":1,"y":10},{"x":2,"y":20}]'
 
+        Test.specify "limit the number of elements" <|
+            vector = [0,10,20,30]
+            text = Scatter_Plot.process_to_json_text vector limit=2
+            json = Json.parse text
+            json.fields.keys.should_equal ['axis','data']
+            data = json.fields.get 'data'
+            data.unwrap.length . should_equal 2
+
+        Test.specify "filter the elements" <|
+            vector = [0,10,20,30]
+            bounds = [0,5,10,25]
+            text = Scatter_Plot.process_to_json_text vector bounds
+            expect_text text no_labels '[{"x":1,"y":10},{"x":2,"y":20}]'
+
         Test.specify "using indices for x if given a column" <|
             column = Column.from_vector 'some_col' [10,2,3]
             expect column (labels 'index' 'some_col') '[{"x":0,"y":10},{"x":1,"y":2},{"x":2,"y":3}]'