Precision error in gradient

[gnefedev]

I plot tiles and lets plot interpret one of existed values as NaN

Code:

var plt = letsPlot(
    mapOf(
        "x" to listOf(
            "first",
            "first",
            "second",
            "third",
            "third"
        ),
        "y" to listOf(
            "18",
            "21",
            "21",
            "18",
            "21",
        ),
        "z" to listOf(
            3.5264934876244764E-7,
            0.0974772170888232,
            0.1116666955828674,
            2.58687631451427E-5,
            0.07896070396295593
        )
    )
)
plt += geomTile(
    width = tileFillWidth,
    height = tileFillHeight
) {
    this.x = "x"
    this.y = "y"
    this.fill = "z"
}
plt += scaleFillGradientN(
    colors = listOf(
        "#DFFADC", "#C9F5D3", "#B3F2CF",
        "#9AEBCD", "#80DCCC", "#6DC8D2",
        "#61B7DB", "#5C97DB", "#5A7CD6",
        "#6060C7", "#674BB3", "#693799",
        "#6A277B", "#671D60", "#611347",
    ),
    naValue = Color.BLACK.toHexColor()
)
println(ObjectMapper().writeValueAsString(plt.toSpec()))

writeFile(Paths.get("tmp/reproduce.svg"), plt)

Specification as Json

{ "mapping": {}, "data": { "x": [ "first", "first", "second", "third", "third" ], "y": [ "18", "21", "21", "18", "21" ], "z": [ 3.5264934876244764E-7, 0.0974772170888232, 0.1116666955828674, 2.58687631451427E-5, 0.07896070396295593 ] }, "kind": "plot", "scales": [ { "aesthetic": "fill", "scale_mapper_kind": "color_gradientn", "na_value": "#000000", "colors": [ "#DFFADC", "#C9F5D3", "#B3F2CF", "#9AEBCD", "#80DCCC", "#6DC8D2", "#61B7DB", "#5C97DB", "#5A7CD6", "#6060C7", "#674BB3", "#693799", "#6A277B", "#671D60", "#611347" ] } ], "layers": [ { "mapping": { "x": "x", "y": "y", "fill": "z" }, "stat": "identity", "width": 0.95, "position": "identity", "geom": "tile", "height": 0.95 } ] }

I expected no black tiles.

I found the source of this behaviour: because of double precision error upper end of the range is not the same as the max value of data. This code divide double by int and multiply it again, in general, it will not be the same as an original.

[gnefedev]

I found one more case with the same problem.

var plt = letsPlot(
    mapOf(
        "x" to listOf(
            "first",
            "first",
            "second",
            "third",
            "third"
        ),
        "y" to listOf(
            "18",
            "21",
            "21",
            "18",
            "21",
        ),
        "z" to listOf(
            3.5264934876244764E-7,
            0.0974772170888232,
            0.1116666955828674,
            2.58687631451427E-5,
            0.5
        )
    )
)
plt += geomTile(
    width = tileFillWidth,
    height = tileFillHeight
) {
    this.x = "x"
    this.y = "y"
    this.fill = "z"
}
plt += scaleFillGradientN(
    colors = listOf(
        "#DFFADC", "#C9F5D3", "#B3F2CF",
        "#9AEBCD", "#80DCCC", "#6DC8D2",
        "#61B7DB", "#5C97DB", "#5A7CD6",
        "#6060C7", "#674BB3", "#693799",
        "#6A277B", "#671D60", "#611347",
    ),
    trans = "log10",
    naValue = Color.BLACK.toHexColor()
)
println(ObjectMapper().writeValueAsString(plt.toSpec()))

writeFile(Paths.get("tmp/reproduce.svg"), plt)

Specifiaction as Json

{ "mapping": {}, "data": { "x": [ "first", "first", "second", "third", "third" ], "y": [ "18", "21", "21", "18", "21" ], "z": [ 3.5264934876244764E-7, 0.0974772170888232, 0.1116666955828674, 2.58687631451427E-5, 0.5 ] }, "kind": "plot", "scales": [ { "aesthetic": "fill", "scale_mapper_kind": "color_gradientn", "na_value": "#000000", "colors": [ "#DFFADC", "#C9F5D3", "#B3F2CF", "#9AEBCD", "#80DCCC", "#6DC8D2", "#61B7DB", "#5C97DB", "#5A7CD6", "#6060C7", "#674BB3", "#693799", "#6A277B", "#671D60", "#611347" ], "trans": "log10" } ], "layers": [ { "mapping": { "x": "x", "y": "y", "fill": "z" }, "stat": "identity", "width": 0.95, "position": "identity", "geom": "tile", "height": 0.95 } ] }

Without trans = "log10" it works fine on these numbers, but with trans it plots one of the tiles as NaN.

Additionally, legend is definitely broken in case of log10

[alshan]

After the fix (left - 1st case, right - 2nd case):