JKQtPlotter/test/jkqtplotter_simpletest_stepplots

Back to JKQTPlotter main page

JKQtPlotter

Step Line Plots in Different Styles

This project (see ./test/jkqtplotter_simpletest_stepplots/) simply creates a JKQtPlotter widget (as a new window) and adds a single line-graph (a sine-wave). Data is initialized from two QVector objects.

The source code of the main application can be found in jkqtplotter_simpletest_stepplots.cpp. For the most part, several datasets of cosine-curves are generated. then thrre tuples of graphs are added: One of type JKQTPxyLineGraph, which simply indicates the location of the actual datapoints. the second is of type JKQTPstepHorizontalGraph, which adds the step-graph to the plot:

	// 3 now we make several plots with different step styles, each one also contains a
    //     symbol plot indicating the location of the datapoints themselves
    JKQTPstepHorizontalGraph* graph;
    JKQTPxyLineGraph* graphL;

    //-- JKQTPstepLeft ----------------------------------------------------------------------------------------
    graph=new JKQTPstepHorizontalGraph(&plot);
    graphL=new JKQTPxyLineGraph(&plot);

    // set data for both graphs
    graph->set_xColumn(columnX); graphL->set_xColumn(graph->get_xColumn());
    graph->set_yColumn(columnY1); graphL->set_yColumn(graph->get_yColumn());

    // set step style
    graph->set_stepType(JKQTPstepLeft);
    graph->set_lineWidth(1);
    graph->set_fillCurve(true);
    graph->set_drawLine(true);
    graph->set_title("JKQTPstepLeft, filled");

Note that you can configure the step type (left/center/right by graph->set_stepType(JKQTPstepLeft). With graph->set_fillCurve(true) you can draw the curve filled until the y=0-axis and with graph->set_drawLine(true) you can switch the line along the values on and off (e.g. to only have the filled area, but no line).

Finally the JKQTPxyLineGraph is configured:

    // set symbol + pen style and color for the added circles, copy color
    graphL->set_symbol(JKQTPgraphSymbols::JKQTPcircle);
    graphL->set_drawLine(false);
    graphL->set_symbolSize(9);
    graphL->set_symbolWidth(1);
    graphL->set_color(graph->get_color());

... and all graphs are added to the plot:

    // add the graphs to the plot, so it is actually displayed
    plot.addGraph(graph);
    plot.addGraph(graphL);

In addition to the symbol type and line style, you can also alter the size of the symbols (graph->set_symbolSize(14)), the line-width used to draw them (graph->set_symbolWidth(1.5)) and the line width of the graph line (graph->set_lineWidth(1)). If you want to switch off the line altogether, use graph->set_drawLine(false.

The result looks like this:

Back to JKQTPlotter main page