JFreeChart Developer Guide (0.9.20)

[david.gilbert]

A new version of the JFreeChart Developer Guide has been released. For more information about how to purchase the guide:

http://www.object-refinery.com/jfreechart/guide.html

The update is free for those that have purchased the guide previously.

[juhi]

Hi David,

I've purchased the Developer Guide as it said that it would help in understanding how to create datasets. however, I haven't been able to find any section in it that really explains how to go about doing so. It just explains the classes and what they are used for. Is there some particular section that I may not be seeing correctly?? Can you please point out which sections in the guide (the latest one) can help me understand how to create datasets. For example, if I want to create an XYPlot, I know that I require an XYDataset, but how is it to be created, or what kind of values do i need to pass to it is a little unclear. Any help in this matter will be highly appreciated.

thanks so much,
Juhi.

[david.gilbert]

Hi Juhi,

I'm working on the JFreeChart Developer Guide right now, so I will try to improve the coverage of the XYDataset interface, how it is used, etc. But to help you along right away:

XYDataset is just an interface, so to create a dataset you need to use a class that implements the interface. JFreeChart provides two classes that should cover most common requirements:

- XYSeriesCollection - for regular (x, y) data items;
- TimeSeriesCollection - for (date, value) data items;

The documentation for these classes has been enhanced just recently, so I've uploaded the latest "work in progress" version of the JFreeChart Developer Guide to the download page (it should be accessible now if you want to take a look).

Two demos worth looking at are XYSeriesDemo.java and TimeSeriesDemo.java (both can be found in the src/org/jfree/chart/demo directory of the JFreeChart 0.9.20 distribution). These show a simple dataset being created, followed by a chart that displays the dataset.

Hope that helps...

Dave

[juhi]

Hi David,

Thanks for that update! I had a question regarding duplicate values which I have not been able to understand. I'm using the XYSeries to create an XYPlot. by using the default constructor, it allows duplicate values. But in my plot I can see only 1 point corresponding to that (x,y) pair. This is exactly what I needed, but I don't understand how it does it when the flag for duplicates is set to true? Also, if I need to do the same thing in histograms - as in, if I'm plotting a histogram based on a column of data (retrieved from a table), and i want NO duplicate values allowed for a specified column (say Id), how do I do that? For example, I have data such as this-
(A,B) - { (1,2),(1,2),(1,2),(3,4),(5,6),(4,5),(9,8),(9,8) }
For this dataset, I want a histogram for values of B, BUT where the values of A are repeated, I don't want to inclue them multiple times. In other words, B value 2 should be taken only ONCE though it is listed 3 times, and B value 8 should be taken only ONCe though it is listed 2 times. Does this make sense??

your help would be appreciated highly!
Thanks,
Juhi.

[david.gilbert]

I'm using the XYSeries to create an XYPlot. by using the default constructor, it allows duplicate values. But in my plot I can see only 1 point corresponding to that (x,y) pair. This is exactly what I needed, but I don't understand how it does it when the flag for duplicates is set to true?

It is probably drawing multiple items on top of one another, but you only see the last one drawn because it obscures the others. That's my guess, anyway.

Also, if I need to do the same thing in histograms - as in, if I'm plotting a histogram based on a column of data (retrieved from a table), and i want NO duplicate values allowed for a specified column (say Id), how do I do that? For example, I have data such as this-
(A,B) - { (1,2),(1,2),(1,2),(3,4),(5,6),(4,5),(9,8),(9,8) }
For this dataset, I want a histogram for values of B, BUT where the values of A are repeated, I don't want to inclue them multiple times. In other words, B value 2 should be taken only ONCE though it is listed 3 times, and B value 8 should be taken only ONCe though it is listed 2 times. Does this make sense??

For this you will need to pre-process your data to remove the duplicates.

[juhi]

Hi David,

thanks for that advice. the flag for allowing duplicates if set to false will take care of the duplicate values in XY-plots right?

I was also asking if there was some way by which I could have a graph showing a grid with different cells colored differently based on some parameters. If I need to accomplish a chart like that - showing different cells, what would be the best renderer and dataset to use?
Can you please help me out with this? I was going through the documentation as well, but as you mentioned that its still a "work-in-progress", I haven't been able to get much of an idea to do this kind of plotting. your help would be very much appreciated!

thanks,
juhi.

[petitlen]

hi david:
I'm a developer from china.I have some question:
1.Jfreechart is very good.But I think it's hard to use as it's docs is so simple and it's class struct is so complex.So I want to get the guide,how can purchase it from china?
2.I have doubt for serval days, how can view the actual value over the position of bar chart etc. I search the docs,beacause the struct is so complex,I didn't know what class to do this,plot?render?or ....
thx:)

[Guest]

Hi David,

I have already purchased the developer guide with v0.9.16. How do i get a new updated one. Thanks,

-Anupma

[david.gilbert]

I have already purchased the developer guide with v0.9.16. How do i get a new updated one.

You can download the latest version using the URL, username and password supplied in your purchase confirmation e-mail.