Coreplot/Xcode帮助：在保持可见X轴的同时放大网格区域

Question

我准备提供我的核心图形的截图供参考，但我还没有被允许（新用户），所以我可以应要求发送电子邮件。

我有一组数据点，其中x值为1〜150，y值为〜300〜450。 我想要做的就是用一个干净的网格覆盖图绘制这些点，放大 y轴（图y轴应该从y min开始，而不是0，并且到y max），同时仍然保留可见的x轴用于参考目的。

我相当接近实现我想要的东西，但我仍然在努力处理一些事情。

首先，我想在y轴和x轴之间的交叉点以及y轴的顶部的y轴上添加一个标签，以便为用户提供参考点。

为了达到这个目的，我已经开始通过玩大滴答间隔，以及在我的数据集上运行一些操作来确定最大和最小值。然而，当我然后尝试放大（即关注y-min和y max之间的范围）时，x轴不再可见。

为了解决这个问题，在整个净一些搜索后我碰到：

axisSet.xAxis.axisConstraints = [CPTConstraints constraintWithLowerOffset：0];

虽然这似乎迫使x轴出现，但它似乎也会抛开我的图形......我的第一个y轴主刻度和原点之间只有3个小刻度，而原点上没有Y轴标签。

有没有人知道如何实现这个偏移量，同时强制原点成为第一个主刻度，并在原点和y-Max上显示y轴的标签？

作为一个侧面的问题，没有人知道如何显示x轴标签作为整数，而不是浮动（希望切断小数）？

我会扔我的源代码，我已经取得了迄今为止以下。

感谢，

布兰登用于初始化情节

源代码：

- （无效）{initialisePlot

[self setDataMaxAndMins]; 

// Create a graph object which we will use to host just one scatter plot. 
CGRect frame = [self.hostingView bounds]; 
self.graph = [[CPTXYGraph alloc] initWithFrame:frame]; 

// Add some padding to the graph, with more at the bottom for axis labels. 
self.graph.plotAreaFrame.paddingTop = 50.0f; 
self.graph.plotAreaFrame.paddingRight = 50.0f; 
self.graph.plotAreaFrame.paddingBottom = 100.0f; 
self.graph.plotAreaFrame.paddingLeft = 120.0f; 

// Tie the graph we've created with the hosting view. 
self.hostingView.hostedGraph = self.graph; 

self.hostingView.backgroundColor = [UIColor blackColor]; 

// Create a line style that we will apply to the axis 
CPTMutableLineStyle *axisStyle = [CPTMutableLineStyle lineStyle]; 
axisStyle.lineColor = [CPTColor grayColor]; 
axisStyle.lineWidth = 2.0f; 


CPTColor * customGray = [CPTColor colorWithComponentRed:0.6f green: 0.6f blue: 0.6f alpha: 1.0f]; 
CPTMutableLineStyle *gridStyle = [CPTMutableLineStyle lineStyle]; 
gridStyle.lineColor = customGray; 
gridStyle.lineWidth = 2.0f; 

//Create plot symbol style 
CPTMutableLineStyle * plotStyle = [CPTMutableLineStyle lineStyle]; 
plotStyle.lineColor = [CPTColor whiteColor]; 
plotStyle.lineWidth = 2.0f; 

// Create a text style that we will use for the axis labels. 
CPTMutableTextStyle *textStyle = [CPTMutableTextStyle textStyle]; 
textStyle.fontName = @"Helvetica"; 
textStyle.fontSize = 20; 
textStyle.color = [CPTColor whiteColor]; 

// Create the plot symbol we're going to use. 
CPTPlotSymbol *plotSymbol = [CPTPlotSymbol ellipsePlotSymbol]; 
plotSymbol.lineStyle = plotStyle; 
plotSymbol.size = CGSizeMake(3.0, 3.0); 
//plotSymbol. 


// Setup some floats that represent the min/max values on our axis. 
float xAxisMin = xMin; 
float xAxisMax = xMax + 5; 
float yAxisMin = yMin; 
float yAxisMax = yMax + 5; 

// We modify the graph's plot space to setup the axis' min/max values. 
CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)self.graph.defaultPlotSpace; 
plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(xAxisMin) length:CPTDecimalFromFloat(xAxisMax - xAxisMin)]; 
plotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(yAxisMin) length:CPTDecimalFromFloat(yAxisMax - yAxisMin)]; 

// Modify the graph's axis with a label, line style, etc. 
CPTXYAxisSet *axisSet = (CPTXYAxisSet *)self.graph.axisSet; 

axisSet.xAxis.title = xAxisTitle; 
axisSet.xAxis.titleTextStyle = textStyle; 
axisSet.xAxis.titleOffset = 50.0f; 
axisSet.xAxis.axisLineStyle = axisStyle; 
axisSet.xAxis.majorTickLineStyle = axisStyle; 
axisSet.xAxis.minorTickLineStyle = axisStyle; 
axisSet.xAxis.labelTextStyle = textStyle; 
axisSet.xAxis.labelOffset = 3.0f; 
axisSet.xAxis.majorIntervalLength = CPTDecimalFromFloat((xAxisMax - xAxisMin)/4);//CPTDecimalFromFloat(25.0f); 
axisSet.xAxis.minorTicksPerInterval = 4; 
axisSet.xAxis.minorTickLength = 5.0f; 
axisSet.xAxis.majorTickLength = 7.0f; 


axisSet.yAxis.title = [yAxisTitle stringByAppendingString: @" ($M)"]; 

axisSet.yAxis.titleTextStyle = textStyle; 
axisSet.yAxis.titleOffset = 80.0f; 
axisSet.yAxis.axisLineStyle = axisStyle; 
axisSet.yAxis.majorTickLineStyle = axisStyle; 
axisSet.yAxis.minorTickLineStyle = axisStyle; 
axisSet.yAxis.labelTextStyle = textStyle; 
axisSet.yAxis.labelOffset = 3.0f; 
axisSet.yAxis.majorIntervalLength = CPTDecimalFromFloat((yAxisMax - yAxisMin)/4); 
axisSet.yAxis.minorTicksPerInterval = 4; 
axisSet.yAxis.minorTickLength = 5.0f; 
axisSet.yAxis.majorTickLength = 7.0f; 

CPTColor * customLighterBlue = [CPTColor colorWithComponentRed:0.0f green: 0.0f blue: 0.4f alpha: 1.0f]; 
CPTColor * customDarkBlue = [CPTColor colorWithComponentRed:0.0f green: 0.0f blue: 0.3f alpha: 1.0f]; 
axisSet.xAxis.alternatingBandFills = [NSArray arrayWithObjects:customLighterBlue, customDarkBlue, nil]; 

axisSet.xAxis.majorGridLineStyle = gridStyle; 

axisSet.yAxis.majorGridLineStyle = gridStyle; 

axisSet.xAxis.axisConstraints = [CPTConstraints constraintWithLowerOffset:0]; 


// Add a plot to our graph and axis. We give it an identifier so that we 
// could add multiple plots (data lines) to the same graph if necessary. 
CPTScatterPlot *plot = [[CPTScatterPlot alloc] init]; 
plot.dataSource = self; 
plot.identifier = @"mainplot"; 
plot.dataLineStyle = nil; 
plot.plotSymbol = plotSymbol; 
[self.graph addPlot:plot]; 

//[_graph.defaultPlotSpace scaleToFitPlots:[_graph allPlots]]; 

}

Answer 1

1. 更改标签政策。我认为CPTAxisLabelingPolicyEqualDivisions会做你想做的。在Plot Gallery示例应用程序中有一个演示，其中显示了所有可用的标签策略。

2. 在x轴上设置labelFormatter。这是一个标准的NSNumberFormatter。