I want to do something that can be simplified into the following toy example: I want to dynamically show the count down to a future date on an AngularGage. The following code works,

x = Dynamic[Refresh[DateDifference[Now,FutureDate,"Minute",UpdateInterval->0.1]

but the gauge displays an unwanted second hand. How do I get rid of it? The deeper question is about the complicated nature of dynamic variables, as demonstrated in the TreeForm image below. How do you use these kind of variables?

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2 Answers 2


Don't know why but if you have a Quantity[513.2441798845927, "Minutes"] wrapped with Dynamic, then AngularGauge can't handle it and shows two inputs, 513.23 and "Minutes" (blue one).

I also don't know if that's suppose to happen but here's a work around:

Use QuantityMagnitude:

     QuantityMagnitude @ DateDifference[Now, Tomorrow, "Minute"], 
     UpdateInterval -> 0.1
 {0, 1000}]

Or don't use the inner Dynamic since there is one outside anyway:

  Refresh[DateDifference[Now, Tomorrow, "Minute"], 
   UpdateInterval -> 0.1], {0, 1000}]]

The former method gives you more flexibility I think.

  • $\begingroup$ So, I guess one of the underlying questions is how to return just the numerical part of a dynamic value that is returned with the unit it is expressed in ... $\endgroup$ Apr 25, 2016 at 14:21
  • $\begingroup$ @GeorgeWolfe As shown above, you can use QuantityMagnitude and AngularGuge will digest it well. $\endgroup$
    – Kuba
    Apr 25, 2016 at 14:22
  • $\begingroup$ Oh, ok - QuantityMagnitude $\endgroup$ Apr 25, 2016 at 14:23

It can also be done this way. I recommend it because it avoids passing any complicated dynamic expression to AngularGauge.

    Quantity[DateDifference[Now, Tomorrow, "Minute"]], 
    {Quantity[0, "Minute"], Quantity[800, "Minute"]}, 
    GaugeLabels -> "Unit"], 
  UpdateInterval -> 1]


The tooltip confirms that the gauge is dynamically updating.

  • $\begingroup$ I appreciate these answers. I'm learning more than I expected. $\endgroup$ Apr 25, 2016 at 21:25

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