Datasets Overview

This page describes the basic steps and related subroutine calls for supplying data to the charting routines.

Description:

The data to be plotted on a chart is kept in a 'dataset'. There is no specific limit to the number of 'points' in your dataset. You can also manage more than one dataset at a time by giving each dataset a unique name when you initialize it.

The general flow is to initialize a dataset, then use various subroutines to add data to your dataset. When you initialize a Pie chart, a dataset is initialized automatically for you. If you already have a dataset initialized when you call the chart initialization routine for a Pie chart, then that dataset will be associated with the new chart.

Certain chart types have specific routines for defining layers of data, ie, a bar chart that plots more than one set of data. These are discussed under the API's for that particular chart type. Pie charts have a specific API that lets you add a datapoint and a label for it at the same time (see Chart design example).

The following code illustrates adding a layer of data to a bar chart:

   *    ================================================================
   *
   *    Add a bar chart layer to the chart
   GOSUB  0CD .XY ADD BAR LAYER
   *
   *    Add data group
   GOSUB  0CD .LAYER ADD DATA GROUP
   *
   *    Add dataset
   GOSUB  0CD .LAYER ADD DATASET
   *    ================================================================
   *    Initialize dataset
   *    ================================================================
   PASS    1             FIELD      SHARE? N
   GOSUB  0CD .DATASET INITIALIZE
   *
   *    Link dataset to group
   GOSUB  0CD .LAYER LINK DATASET
   *
   *    ================================================================
   *    Add data to dataset
   *    ================================================================
   *
   PASS    85            FIELD      SHARE? N
   GOSUB  0CD .POINT ADD NEW
   *
   PASS    156            FIELD      SHARE? N
   GOSUB  0CD .POINT ADD NEW
   *
   PASS    179.5           FIELD      SHARE? N
   GOSUB  0CD .POINT ADD NEW
   *
   PASS    211            FIELD      SHARE? N
   GOSUB  0CD .POINT ADD NEW
   *
   PASS    123            FIELD      SHARE? N
   GOSUB  0CD .POINT ADD NEW

Generally, when you render the chart the API's will use whatever dataset is the 'current' dataset. If you are working with multiple named datasets, there is an API that allows you to change the current dataset.

Comments

Read what other users have said about this page or add your own comments.

-- JeanNeron - 2011-09-21