improved default tick layout for log scales (6df73dd3) · Commits · github_fork / Clip

core/scale.cc

+88 −15

Original line number	Diff line number	Diff line
		@@ -25,6 +25,7 @@ namespace fviz {

		static const double kDefaultLogBase = 10;
		static const size_t kMaxTicks = 8192;
		static const double EPSILON = 0.001;

		ScaleConfig::ScaleConfig() :
		kind(ScaleKind::LINEAR),
		@@ -78,19 +79,25 @@ double scale_translate_linear(
		double scale_translate_log(
		const ScaleConfig& domain,
		double v) {
		if (v <= 0) {
		return 0;
		}

		auto min = scale_min(domain);
		auto max = scale_max(domain);
		auto log_base = domain.log_base;
		double range_log = log(max - min) / log(log_base);

		auto vf = v - min;
		if (vf >= 1.0) {
		double min_log = min == 0 ? 0 : log(min) / log(log_base);
		double max_log = max == 0 ? 0 : log(max) / log(log_base);

		auto vf = v;
		if (vf != 0.0) {
		vf = log(vf) / log(log_base);
		} else {
		vf = 0;
		}

		auto vt = vf / range_log;
		auto vt = (vf - min_log) / (max_log - min_log);
		if (domain.inverted) {
		vt = 1.0 - vt;
		}
		@@ -360,24 +367,29 @@ ReturnCode scale_layout_exponential_steps(
		ScaleLayout* layout,
		double base,
		size_t steps) {
		auto begin = scale_min(domain);
		auto end = scale_max(domain);
		double min = scale_min(domain);
		double max = scale_max(domain);
		double exp = min == 0 ? 0 : log(min) / log(domain.log_base);

		for (size_t idx = 0, exp = 0; ; ++idx) {
		for (size_t idx = 0; ; ++idx) {
		auto v = pow(base, exp++);
		auto vn = pow(base, exp);

		if (v < begin) {
		if (v < min) {
		continue;
		}

		if (v > end) {
		if (v > max + EPSILON) {
		break;
		}

		for (size_t s = 0; s < steps - 1; ++s) {
		auto vs = v + (s / double(steps - 1)) * (vn - v);
		auto vp = scale_translate(domain, vs);
		if (vs > max + EPSILON) {
		break;
		}

		layout->positions.emplace_back(vp);
		layout->labels.emplace_back(label_format(idx++, std::to_string(v))); // FIXME
		}
		@@ -391,20 +403,23 @@ ReturnCode scale_layout_exponential(
		const Formatter& label_format,
		ScaleLayout* layout,
		double base) {
		auto begin = scale_min(domain);
		auto end = scale_max(domain);
		double min = scale_min(domain);
		double max = scale_max(domain);
		double exp = min == 0 ? 0 : log(min) / log(domain.log_base);

		for (size_t idx = 0, exp = 0; ; ++idx) {
		size_t idx = 0;
		for (;;) {
		auto v = pow(base, exp++);
		if (v < begin) {
		auto vp = scale_translate(domain, v);

		if (v < min) {
		continue;
		}

		if (v > end) {
		if (v > max + EPSILON) {
		break;
		}

		auto vp = scale_translate(domain, v);
		layout->positions.emplace_back(vp);
		layout->labels.emplace_back(label_format(idx++, std::to_string(v))); // FIXME
		}
		@@ -748,6 +763,64 @@ ReturnCode scale_configure_layout(
		" - categorical-bounds\n");
		}

		void scale_configure_layout_defaults(
		const ScaleConfig& config,
		ScaleLayoutFn* label_placement,
		ScaleLayoutFn* tick_placement) {
		// default label placement
		if (label_placement && !*label_placement) {
		switch (config.kind) {
		case ScaleKind::CATEGORICAL:
		*label_placement = bind(&scale_layout_categorical, _1, _2, _3);
		break;
		case ScaleKind::LOGARITHMIC:
		*label_placement = bind(
		&scale_layout_exponential,
		_1,
		_2,
		_3,
		config.log_base);
		break;
		default:
		*label_placement = bind(&scale_layout_subdivide, _1, _2, _3, 10);
		break;
		}
		}

		// default tick placement
		if (tick_placement && !*tick_placement) {
		switch (config.kind) {
		case ScaleKind::CATEGORICAL:
		*tick_placement = bind(&scale_layout_categorical_bounds, _1, _2, _3);
		break;
		case ScaleKind::LOGARITHMIC:
		if (config.log_base == 10) {
		*tick_placement = bind(
		&scale_layout_exponential_steps,
		_1,
		_2,
		_3,
		10,
		10);
		} else {
		*tick_placement = bind(
		&scale_layout_exponential,
		_1,
		_2,
		_3,
		config.log_base);
		}
		break;
		default:
		if (label_placement) {
		tick_placement = label_placement;
		} else {
		*tick_placement = bind(&scale_layout_subdivide, _1, _2, _3, 10);
		}
		break;
		}
		}
		}

		} // namespace fviz

core/scale.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -146,5 +146,10 @@ ReturnCode scale_configure_layout(
		const Expr* expr,
		ScaleLayoutFn* layout);

		void scale_configure_layout_defaults(
		const ScaleConfig& config,
		ScaleLayoutFn* label_placement,
		ScaleLayoutFn* tick_placement);

		} // namespace fviz

elements/plot/axis.cc

+5 −25

Original line number	Diff line number	Diff line
		@@ -752,27 +752,11 @@ ReturnCode build(const Environment& env, const Expr* expr, ElementRef* elem) {
		}
		}

		if (!config->label_placement) {
		switch (config->scale.kind) {
		case ScaleKind::CATEGORICAL:
		config->label_placement = bind(&scale_layout_categorical, _1, _2, _3);
		if (!config->tick_placement) {
		config->tick_placement = bind(&scale_layout_categorical_bounds, _1, _2, _3);
		}
		break;
		case ScaleKind::LOGARITHMIC:
		config->label_placement = bind(
		&scale_layout_exponential,
		_1,
		_2,
		_3,
		config->scale.log_base);
		break;
		default:
		config->label_placement = bind(&scale_layout_subdivide, _1, _2, _3, 10);
		break;
		}
		}
		/* setup defaults */
		scale_configure_layout_defaults(
		config->scale,
		&config->label_placement,
		&config->tick_placement);

		if (!config->label_formatter) {
		if (config->scale.kind == ScaleKind::CATEGORICAL) {
		@@ -782,10 +766,6 @@ ReturnCode build(const Environment& env, const Expr* expr, ElementRef* elem) {
		}
		}

		if (!config->tick_placement) {
		config->tick_placement = config->label_placement;
		}

		*elem = std::make_shared<Element>();
		(*elem)->draw = bind(&axis_draw, config, _1, _2);
		(*elem)->size_hint = bind(&axis_calculate_size, config, _1, _2, _3, _4, _5);

elements/plot/grid.cc

+2 −15

Original line number	Diff line number	Diff line
		@@ -108,21 +108,8 @@ ReturnCode build(const Environment& env, const Expr* expr, ElementRef* elem) {
		return config_rc;
		}

		if (!c->layout_x) {
		if (c->scale_x.kind == ScaleKind::CATEGORICAL) {
		c->layout_x = bind(&scale_layout_categorical, _1, _2, _3);
		} else {
		c->layout_x = bind(&scale_layout_subdivide, _1, _2, _3, 10);
		}
		}

		if (!c->layout_y) {
		if (c->scale_y.kind == ScaleKind::CATEGORICAL) {
		c->layout_y = bind(&scale_layout_categorical, _1, _2, _3);
		} else {
		c->layout_y = bind(&scale_layout_subdivide, _1, _2, _3, 10);
		}
		}
		scale_configure_layout_defaults(c->scale_x, nullptr, &c->layout_x);
		scale_configure_layout_defaults(c->scale_y, nullptr, &c->layout_y);

		*elem = std::make_shared<Element>();
		(*elem)->draw = bind(&draw, c, _1, _2);

examples/charts-basic/histogram.svg

+32 −0

Original line number	Diff line number	Diff line
		@@ -21,9 +21,41 @@
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