In BIRT is it possible to create a chart from summarized data columns? - charts

Question

Is it possible to create a line chart using summarized data from dataset?
My scenario is the following:
detail section: each one of the cells are one output field in the dataset
JAN FEB MAR
item1 R X R
item2 X A R
item3 R R R
footer section: here we count the occurrence of each value per month by using count aggregation elements and filter by value
TOTALS:
R 2 1 3
X 1 1 0
A 0 1 0
And what I need to do is to add a chart that shows something like this:
Needed Chart
And what I have is this:
report output
report design
In EXCEL this is really simple, but I cannot figure out how it can be done in BIRT.
I thought something like to create a new data set with 3 output fields for R, X, and A and each row will be one month, so I will have a transposed table and that way it will me much easier for graph it. But I cannot do it using the aggregation fields, and I cannot find out how to it with the output fields from the main dataset.
Any ideas? If you need the source rptdesign file I can provide it to you, but the logic in it could be hard to understand.
Any help is appreciated, and thanks in advance.
Have a great 2020.

Answer 1

First of all, a BIRT rule of thumb: if you need aggregations outside of a table, create them outside of a table. Do not try to access values in a table from the outside. It is possible, it may sometimes be the only solution, but it usually messes up your whole report, it is hard to debug, and even harder to maintain.
Aggregate
As your dataset looks quite simple and you already know how and what to aggregate, your first call should be computed columns in the dataset:
Here you aggregate in the language according to your datasource. If that is SQL, I guess a COUNT and GROUP BY statement will do the job.
Create all the columns you need for your graph here.
BTW: Computed columns are usually the silver bullet in BIRT. I use them for almost any pre-computation or custom field creation.
Visualize
You did not mention the library you are using for graphs, so I will assume you want to use the basic BIRT graphs. The basic charts with the months on the x-axis will do your job. I just want to add here that you have two options for multiple series:
You can either prepare your dataset so that you can feed the graph with a series per type (one line in your chart example) OR maybe easier: use optional y series grouping on your computed columns (as mentioned):
This way your graph will create the separate series for you. I hope this helps!
If you get stuck with the basic birt grpahs in general, you might want to think about finding a JavaScript-based graph library that does exactly what you need and implement that. Remember: you can put almost anything that is based on JavaScript into BIRT.
Final remark: For the sake of your report end users, please use a multi-bar chart. Line charts are not readable for overlapping values.

Answer 2

Thanks Kekzpanda for your help and time helping me in this question I had.
After struggling for a while I finally reach for a solution transposing the "table" of aggregations I had in the table footer, by using javascript arrays and an extra dataset and here are the steps I did in case someone else have the same problem:
For example, you need to transpose a table of 10 columns and 3 records
In report initialize method create an array with [10,3] dimension
// bi dimensional array indexes
var i=0;
var j=0;
// array definition and initialize it using 'for' iteration
var matriz = new Array(10);
for (i=0;i<10;i++){
matriz[i] = new Array(3);
}
// restart the array indexes in case you need to go through it in the future
i=0;
j=0;
Then you need to save the aggregation field value in one of the positions in the array. For that click on the aggregation field and go to the onCreate method and add the following code:
matriz[0][1]=this.getValue();
When finish all the aggregation fields, you will have an array with the transpose table. CHECKED!
Move the data in the array to the new dataset, select the fetch method and add something like this:
if(i >= array.length) return(false); // when you finish going through each item in the array.
row["A"]=matriz[i][0];
row["B"]=matriz[i][1];
row["C"]=matriz[i][2];
i++; // increment the first index by 1 to move to next row in the array
return (true);
Now you have your new data set with the transpose data.
Now work with this data set and graph the data, create the different series in the graph design for each column in the dataset.
Hope this help.
Bye.