Log Minor Grid Lines

rborn · Post by **rborn** » Wed Mar 18, 2009 9:35 am

Is there a way to get anything other than 10 minor grid lines between major divisions in a log scale? Whenever I try to change the "Minor grid/tick divisions on Y (or X) axis" to anything other than "1", it puts in 10 minor divisions. Maybe this is inherent in a log scale but I would think you should at least be able to just do the even for example [2,4,6,8] numbers to reduce the number of grid/tick lines.

This should probably be another post, but you can't put minor grid lines between one set of major divisions of an axis and not another can you? When using a log scale, some of the major divisions are close together and some are far apart. I would like to put in minor grid/tick divisions for the major divisions that are far apart but not on the ones close together. The graph gets a bit cluttered when the minor graph/tick marks are put between the major graph/tick marks that are close together. Normally this isn't an issue but it's for a presentation graph and it would help keep it less clutter for this one purpose.

rborn · Post by **rborn** » Wed Mar 18, 2009 9:52 am

I just noticed that quite interestingly, the program automatically reduces the number of minor grid/tick lines between major lines when the major lines are close together. This is not unexpected, but the minor divisions can be reduced to something other than 10. When I set the major divisions to 1 and the minor to 3 (just for testing), it puts in 10 minor where it can fit them in and 5 where it can't.

Post by **DPlotAdmin** » Thu Mar 19, 2009 8:14 am

Is there a way to get anything other than 10 minor grid lines between major divisions in a log scale?

No, sorry. That's a good suggestion for a future release, though. One problem is that DPlot already does this, in a way. From 1 to 5 you get every 0.1 interval, from 5 to 10 you get intervals at 0.2. So a single value won't work - at least not with how things work currently. Maybe 3 settings: a) same as the current version: 0.1 from 1 to 5, 0.2 from 5 to 10. b) 0.2 from 1 to 5, 0.5 from 5 to 10, c) 0.5 from 1 to 10. And then someone will want these 2 settings, so a2) 0.1 from 1 and 10 and b2) 0.2 from 1 to 10. I'll think on this one a bit.

When I set the major divisions to 1 and the minor to 3 (just for testing), it puts in 10 minor where it can fit them in and 5 where it can't.

I'm guessing you meant X and Y rather than major and minor - otherwise I'm not sure what you mean. In any case DPlot isn't doing anything quite as smart as you're reading into this - "where it can fit them" is between 1 and 5 (or 10 and 50, etc.)

rborn · Post by **rborn** » Thu Mar 19, 2009 9:50 am

Sorry, when I said major I meant "Tick mark interval on X (or Y) axis" and by minor I meant "Minor grid/tick divisions on X (or Y) axis". Both of these are found under Options, Extents/Intervals/Size. I'm not sure we are on the same page or not since you suggested three options for the issue and I am not sure why you can't have it work like a normal "Linear" axis. I would understand if you couldn't change the Tic mark interval for the axis since it's a log, although maybe it should still be possible. What if you want 12 intervals? I'm not a log graph expert so maybe this isn't even logical. On a linear axis, I can change this to whatever I want and it adjusts accordingly. I can also change the Minor grid/tick division to anything and it adjusts. On the graph below I have changed the Y-axis minor grid/tick interval to 3, there are 3 intervals between the Major intervals (not that this makes sense for this graph).

I thought it would be logical to put in 5 Minor grid/tick divisions on Y axis for the log axis and it would reduce the divisions by half (since 10 seems to be the default, except where you noted). Now my minor divisions between 1.0 and 2.0 on a log axis would be 1.0, 1.2, 1.4, 1.6, 1.8, and 2.0. This seems logical to me, please let me know if I'm off base.

In the log graph below, I changed the Minor grid/tick interval to 3 and asked it to display the labels for "Minor tick Marks". There are two things you will notice, and one I'm not sure if it's a bug or not. First, the minor grid/ticks is either 5 or 10, as you described, but not 3 (just so you know what I was referring to in the previous post). Second, it seems to randomly pick which minor Log Scale tick labels to display. If you look between 1 and 2, it shows some odd labels (1.1, 1.5, and 1.7) but not 1.3, and only shows one even tick (1.2). This is not what I expected, I expected it to show all the even ones or at least, just all the odd. I'm guessing it is trying to display all the labels but needs to hide some since they won't all fit. But, it seems random, and to me, not correct. Maybe this is consistent with how the other graph types work, it just shows up here since it is logarithmic. If it could reduce the number of minor grid/ticks to 5 on maybe 2, it would probably only show the even ones.