gallery_multi_trace_styling.cpp

This gallery example demonstrates creating plots with multiple traces and advanced styling options using Plotly.cpp. It showcases different line styles, colors, and mathematical functions plotted together with custom legend configuration.

Features demonstrated:

• Multiple trace plotting with different mathematical functions
• Custom line styling (solid, dashed lines with different colors)
• Automatic and manual color assignment for traces
• Legend configuration and trace naming
• Axis range control and custom plot dimensions
• Mathematical function visualization (sine, logarithmic, constant functions)

The plot displays three mathematical relationships:

• A sine wave function showing periodic behavior
• A logarithmic growth curve demonstrating non-linear scaling
• A constant horizontal line for reference comparison

Multi-Trace Mathematical Functions Plot

 
#include "plotly/plotly.hpp"
#include "utils/arg_parser.hpp"
#include <cmath>
#include <vector>
 
auto main(int argc, char *argv[]) -> int {
  // Parse command line arguments
  auto args = parseGalleryArgs(argc, argv);
 
  plotly::Figure fig;
  fig.openBrowser(args.headless);
 
  // Prepare data - equivalent to matplotlib example
  int n = 5000;
  std::vector<double> x(n), y(n), z(n), w(n, 2.0);
 
  for (int i = 0; i < n; ++i) {
    x[i] = i * i;
    y[i] = std::sin(2 * M_PI * i / 360.0);
    z[i] = std::log(i + 1); // +1 to avoid log(0)
  }
 
  // Create traces equivalent to matplotlib plots
 
  // First trace: plot(x, y) - automatically colored line
  plotly::Object trace1 = {{"x", x},
                           {"y", y},
                           {"type", "scatter"},
                           {"mode", "lines"},
                           {"name", "sin(2πi/360)"}};
 
  // Second trace: plot(x, w, "r--") - red dashed line
  plotly::Object trace2 = {
      {"x", x},
      {"y", w},
      {"type", "scatter"},
      {"mode", "lines"},
      {"line", plotly::Object{{"color", "red"}, {"dash", "dash"}}},
      {"name", "constant line (y=2)"}};
 
  // Third trace: named_plot("log(x)", x, z) - named line for legend
  plotly::Object trace3 = {{"x", x},
                           {"y", z},
                           {"type", "scatter"},
                           {"mode", "lines"},
                           {"name", "log(x)"}};
 
  // Layout configuration equivalent to matplotlib settings
  plotly::Object layout = {
      {"title", {{"text", "Sample figure"}}},
      {"xaxis",
       {
           {"title", {{"text", "X values"}}},
           {"range", plotly::Array{0, 1000000}} // xlim(0, 1000*1000)
       }},
      {"yaxis", {{"title", {{"text", "Y values"}}}}},
      {"showlegend", true}, // Enable legend
      {"width", 1200},      // Set figure size
      {"height", 780}};
 
  // Create the plot with all traces
  std::vector<plotly::Object> data = {trace1, trace2, trace3};
  fig.newPlot(data, layout);
 
  if (!args.headless) {
    fig.waitClose();
  } else {
    // Save the image equivalent to plt::save("./basic.png")
    plotly::Object imageOpts = {{"format", "png"},
                                {"width", 1200},
                                {"height", 780},
                                {"filename", "multi_trace_styling"}};
    fig.downloadImage(imageOpts);
  }
 
  return 0;
}