PDA

View Full Version : Chart maximum/minimum value not rendered



rhvt
2 May 2016, 7:13 AM
Hi,

I'm currently encountering an issue with Ext JS charts.
I'm using a classic line chart to show cartesian points (x,y).
I have a pretty large amount of points (>10 000).

While I'm parsing my points at server-side (I'm doing some business to adapt values into cartesian point model) I'm also looking for the minimum and maximum values.

Though I have theses values, the line in my chart isn't reaching theses values.

I provide a sample in the attachements.

The first rectangle shows my charts.

The second one is showing a client-side trace while I'm parsing the results from server, and you can see that I find a maximum value which is most likely close to the maximum value returned by server (it's the chart maximum value), though my chart isn't going to this value.

Do i have too many points and that could affect the chart accuracy ? (If only one point out of 10 000 is reaching this value, maybe the chart skip it to make the line smooth, idk).

Gary Schlosberg
3 May 2016, 7:50 AM
How are you deriving that maximum number? I would say that 10,000 points is more than can be reasonably rendered in chart which is 500-600 pixels wide. Certainly it leaves much to be interpreted in the rendering.

rhvt
3 May 2016, 11:08 PM
Hello Gary,Sorry english is not my native language, I can't figure out what do you mean by deriving ?

Gary Schlosberg
20 May 2016, 5:36 AM
Oh sorry, I just was asking how you were calculating the maximum and minimum for the Y axis. I think you're correct that some values are being dropped since that many points cannot be accurately displayed with so few pixels.