Question

What algorithm or formula would you recommend to set the labels on the y-axis to multiples of 5 or 10 in CorePlot?

I basically want to get even numbering, for instance: 5, 10, 15, 20 or 100, 105, 110, 115… and set the maximum number of y-labels to 10.

Any ideas would be welcome! Thank you!!

Answer 1

This is controlled by the “labeling policy”. You have several choices:

typedef enum _CPTAxisLabelingPolicy {
    CPTAxisLabelingPolicyNone,              ///< No labels provided; user sets labels and tick locations.
    CPTAxisLabelingPolicyLocationsProvided, ///< User sets tick locations; axis makes labels.
    CPTAxisLabelingPolicyFixedInterval,     ///< Fixed interval labeling policy.
    CPTAxisLabelingPolicyAutomatic,         ///< Automatic labeling policy.
    CPTAxisLabelingPolicyEqualDivisions     ///< Divide the plot range into equal parts.
} CPTAxisLabelingPolicy;

If you know how far apart you want the tick marks, keep the default labeling policy (fixed interval) and set the majorIntervalLength to the desired interval. You could also use the automatic policy to let Core Plot pick the intervals. Use the preferredNumberOfMajorTicks property to give it a hint about how many tick marks to make.