Web traffic chart
This is a bar chart with multiple bars. The data is the traffic of my website http://www.field-theory.org. The data are the number of hits, the number of page views and the number of unique visitors to the site over a period of six months. The demo app shows three different charting options – with the bars side-by-side, overlapping, or stacked.
This page describes the class “WebsiteVisitor” in the PowerPlot demo app.
The chart itself is easily generated using the multiBarPlotWithFrame:data:style:colorScheme: factory method, with the style corresponding to the choice from the UISegmentedControl in the user interface. In this example, a new chart is generated in the method switchStyle:
// Create and configure the bar chart.
WSData *hitsD = [DemoData monthlyHits];
WSData *pageViews = [DemoData monthlyPageviews];
WSData *pageVisitors = [DemoData monthlyVisitors];
BPStyle chosenStyle = [self.styleSelector selectedSegmentIndex] + 1;
WSChart *barChart = [WSChart multiBarPlotWithFrame:[self.visitors frame]
data:[NSArray arrayWithObjects:hitsD,
pageViews, pageVisitors, nil]
style:chosenStyle
colorScheme:kColorWhite];
[barChart scaleAllAxisYD:NARangeMake(-30000, 1.2*[hitsD maximumValue])];
[barChart setAllAxisLocationYD:0];
WSPlotAxis *axis = [barChart firstPlotAxis];
[[axis ticksY] ticksWithNumbers:[NSArray arrayWithObjects:
[NSNumber numberWithFloat:20000],
[NSNumber numberWithFloat:40000],
[NSNumber numberWithFloat:60000],
[NSNumber numberWithFloat:80000],
[NSNumber numberWithFloat:100000],
nil]
labels:[NSArray arrayWithObjects:@"20k", @"40k",
@"60k", @"80k", @"100k", nil]];
// Add the chart and redisplay.
[self.visitors removeAllPlots];
[self.visitors addPlotsFromChart:barChart];
[self.visitors setChartTitle:NSLocalizedString(@"Field-theory.org web traffic", @"")];
[self.visitors setNeedsDisplay];
Here we set the labels of the y-axis manually by using the notion “20k” for 20,000 and so on. This could also be done differently with a custom formatter, but this way is simpler. Note how we configure the ticks manually.
