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Plot is not to y-scale

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      When plotting data imported from a test of a LiFePO4 battery I found the plot does not behave correctly. Depending on the window size in height, the graph displayed does not match the y-scale when under a certain height. Using the loupe, as shown in the figure, the graph is correct with respect to y-scale within the loupe circle but not in the overall window.
      The figure shows the issue and the Upper and Lower lines are added using another program to show where the level intercepts with the y-scale.

      Plot Bug


        There are a combination of things that can contribute to end of the line joins looking like spikes that extend beyond the data  (1) the points are close in one direction, while varying in the other direction (2) the line thickness is a few pixels (3) the default line join is a ‘miter’.

        You could reduce the line thickness to reduce this problem, but we are also adding the option in the Beta version of the program to change the Line join, from ‘miter’ to ‘bevel’.

        Here is a little more background on line joins:

        The underlying issue has to do with how the lines are joined.  The default option in DataGraph is to use a ‘miter’ join, which results in a sharp point.

        This type of line join is typically what is expected for data similar to the example below, and thick lines are not an issue.



        When your data has some noise, then the ‘miter’ option can cause the lines to look exaggerated when the line thickness is increased.

        Here is the same data with a different line thickness.


        The rendering engine has a limit to how ‘sharp’ it will allow the lines to extend.  This can result in a combination of some joins having the ‘miter’ type and some lines having the ‘bevel’ type.



        Your data appears to have this combination of miter and bevel in the loop tool. The rendering is at a different scale in the loop tool, which is why you see that detail more clearly then the graph.

        To give you more control over the type of the line joins, we added an option to the beta version of DataGraph: miter, round, or bevel.


        In the Beta, you’ll find this option by expanding the Plot command:



        Also, a quick way to draw a line in one direction (x or y) is to use a Lines command.  Then you can specify the exact x or y location exactly. No need to use another program 🙂

        You can download the Beta here.

        Please let us know if the new Line join option fixes this issue for you.



          Thank you, for a fantastic response. An answer and a solution after 3 hours, I’m really impressed. I hope there will be a release with the fix through AppStore soon.
          I’ve add some comments about functionality I miss under Feedback and Suggestions.


            Good news to report!

            DataGraph 4.5.1 has been released on the App store with this fix.  (Will be out for all users later today.)

            We try to be very responsive and get fixes out quickly.  This was lucky that we were on the cusp of a releasing a new version when you reported this issue.  In the future, the turn around may not be quite this fast for a new release, but our updates can always be used in our Beta version.

            If you are an App store user, you will need to register your copy of DataGraph downloaded from the App store, through the Account information.

            Once registered, you can download and use the Beta.


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