Date/Time axis is forced for all axis

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I have a 2D wave and have set it up where I store the date& time via a datetime commands into column 0. In the other 3 columns I store data.
Column0 Column1 Column2 Column3
datetime Data1 Data2 Data3

In plotting my data I use column 0 (date/time) as the x axis and then use 3 separate left axis for the other columns. My goal is to create a control chart with a single wave holding all the data.

All is well and I can create 3 vertical spaced graphs sharing a common x axis.

Now the problem:
When I change the x axis the date/time scaling in the modifyaxis dialog it changes the other axis (all y axis) to date/time also. I want the y - axis to all be linear and the x axis date/time. Is there a way to do this or do I have to break my data into separate waves?
hegedus wrote:
When I change the x axis the date/time scaling in the modifyaxis dialog it changes the other axis (all y axis) to date/time also. I want the y - axis to all be linear and the x axis date/time. Is there a way to do this or do I have to break my data into separate waves?


Setting an axis to date/time via the Modify Axis dialog will also change the scaling of the respective wave. Since you specify the first column as x wave it will change the data scaling (of all columns) to "dat" and so the data is interpreted as date/time. This obvisously also affects the y axes.
The only way to circumvent this behaviour that I can see is to separate the first column into an own wave and plot the data versus this one-dimensional wave.
duplicate/r=[][0] 2Dwave dateTimeWave
display 2Dwave[][1] vs dateTimeWave
setscale/d 0,0,"dat",dateTimeWave


A

September 15, 2011 at 05:41 am - Permalink

AWirsing is correct- the date/time aspect of an axis is controlled by the wave's 'dat' scaling units:

DisplayHelpTopic "Date/Time Axes"

Since the wave with all your data has this units setting (as a result of choosing Date/Time in the Modify Axis dialog) then all axes get that setting. The only way to fix it is to create a separate X wave.

This is a historical problem- this method for specifying a date/time axis is rooted in the mists of time (that is, back to 1988 or so) when Igor was very young. It is clearly a design flaw exposed by later enhancements to Igor, including the ability to use subranges of multi-column waves for graphing. It needs to be fixed, but right now I can't say how.

John Weeks
WaveMetrics, Inc.
support@wavemetrics.com

September 15, 2011 at 08:39 am - Permalink