Saturday, 23 July 2011
Data for almost all charts is sent using the
chd parameter. The data must be sent in one of the following formats:- Basic text format is essentially simple floating point numbers from 0—100, inclusive. This format is easy to read and write by hand.
- Text format with automatic scaling scales the chart to fit your data.
- Text format with custom scaling is similar to basic text format, but it lets you specify a custom range using a second URL parameter.
- Simple encoding format lets you specify integer values from 0—61, inclusive, encoded by a single alphanumeric character. This encoding results in the shortest data string of any of the data formats (if any values are greater than 9).
- Extended encoding format lets you specify integer values from 0—4095, inclusive, encoded by two alphanumeric characters. Extended encoding is best suited to a chart with a lot of data and a large data range.
The data values are scaled to fit the format used; see Data Scaling and Axis Scaling for an explanation of how the data is manipulated to fit the chart.
We provide a JavaScript snippet for encoding data into simple encoding or extended encoding formats. Alternatively, several Chart API Group members have contributed other libraries to help with formatting: search the Group archives or visit the related links page on the google-chart-api group site to find them.
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