ScatterPlot

Overview

class omdi::ScatterPlot : public omdi::Plot, public omdi::plots::DataPlot<omdi::Points>

Class for creating 2D scatter plots.

The omdi::ScatterPlot class draws collections of scattered 2D points (e.g. omdi::Points) using ImPlot. It supports:

  • plotting one or more named point datasets,

  • an option to enforce equal aspect ratio for X and Y axes,

  • per-series visual customization via ImPlotSpec,

  • reuse of the common omdi::Plot interface.

Datasets are stored by value inside the inherited omdi::plots::DataPlot<omdi::Points> base, so no external data lifetime management is required.

Usage example

Basic usage with two point sets:

// Create scatter plot with just a label — no data yet
auto scatter = omdi::ScatterPlot { "Scatter Example" };

// Add or replace all datasets at once
scatter.update_all({
  { "set A", omdi::Points { {0.0f, 1.0f, 2.0f}, {1.0f, 0.5f, 0.25f}, 3 } },
  { "set B", omdi::Points { xs_vec, ys_vec, n } }
});

// Or construct with initial data directly:
auto scatter2 = omdi::ScatterPlot { "Scatter Example", {
  { "set A", omdi::Points { xs_vec, ys_vec, n } }
}};

// Inside your ImGui/ImPlot drawing code:
scatter.plot();

Data members

bool omdi::ScatterPlot::m_aspect_equal

Flag controlling whether the plot uses an equal aspect ratio.

When true, the X and Y axes are scaled so that one unit in X matches one unit in Y, which is useful for geometric or spatial data. When false, the aspect ratio is free.

Constructor

omdi::ScatterPlot::ScatterPlot(const std::string &label = "ScatterPlot", const std::map<std::string, omdi::Points> &data = {}, bool aspect_equal = true)

Construct a scatter plot with an optional label and initial datasets.

Parameters:

  • label – Plot label / title (used in ImPlot). Defaults to "ScatterPlot".

  • data – Map from dataset names to omdi::Points values. Data is copied into the plot on construction. Defaults to an empty map.

  • aspect_equal – Whether to enforce equal aspect ratio for the axes (defaults to true).

Inherited from DataPlot<Points>

The following methods are inherited from omdi::plots::DataPlot<omdi::Points> and can be called directly on a omdi::ScatterPlot instance.

void omdi::ScatterPlot::update(const std::string &label, omdi::Points data)

Replace or insert a single named point dataset.

Parameters:

  • label – Name of the dataset to update.

  • data – New omdi::Points value (copied by value).

void omdi::ScatterPlot::update_all(std::map<std::string, omdi::Points> new_data)

Replace all datasets at once.

Parameters:

new_data – Map of new datasets. Replaces the entire contents of the internal data store.

auto omdi::ScatterPlot::set_spec(const std::string &label, const ImPlotSpec &spec) -> void

Set the per-series plot specification for a named dataset.

Parameters:

  • label – Dataset label to associate the spec with.

  • spec – ImPlotSpec controlling the visual appearance of the series.

auto omdi::ScatterPlot::get_spec(const std::string &label) const -> ImPlotSpec

Get the per-series plot specification for a named dataset.

Parameters:

label – Dataset label whose spec to retrieve.

Returns:

The ImPlotSpec associated with label.

Plotting

void omdi::ScatterPlot::plot() override

Render the scatter plot.

This method overrides omdi::Plot::plot() and:

  • iterates over the entries in the internal data map,

  • for each dataset, retrieves the X/Y arrays and point count from the corresponding omdi::Points,

  • applies the per-series ImPlotSpec (retrieved via omdi::ScatterPlot::get_spec()) to control visual style,

  • draws the points using ImPlot’s scatter/marker primitives,

  • applies equal aspect ratio if omdi::ScatterPlot::m_aspect_equal is true.

It is typically called inside an ImGui/ImPlot plotting context.

Notes