Updating Labels in VPython Shell

[Tyler M]

Hello,

Does anyone know if it is possible to update the text inside of a label in the VPython shell?  I am trying to make a visible counter/timer, and I would prefer it to be in the shell rather than the print statement window.

So far I have tried to set the text equal to the variable:

variable = 0     #Initial value of variable

label(pos=(0,0,0),text = variable)

#Variable then gets updated in a loop

I have also tried to create new labels to go on top of the previous ones as the counter progresses:

condition = false   #Initial condition

label(pos = (0,0,0), text = '0')

#Inside of loop:

    #Update condition

    #if condition = true:

        label(pos = (0,0,0),text='1')

    #if condition = true again:

        label(pos = (0,0,0),text='2')

Please keep in mind I am trying to outline my general methodology for simplification purposes.  This is not my actual code!  So far, neither method has worked.  The first program yields the error message:

ArgumentError: Python argument types in

    None.None(label, int)

did not match C++ signature:

    None(cvisual::label {lvalue}, std::basic_string<wchar_t, std::char_traits<wchar_t>, std::allocator<wchar_t> >)

I realize the error comes from me not putting text = 'variable', but then it just prints the word variable and no longer a number that I can update.

The second program almost works.  It does print a new label over the old one, but not when I want it to.  Because of this I figured I had made an error in the part of the code I labeled #if condition = true.  Nope.  I tested it, and it works when I create a print statement for the other window, but I want the print statement to be in the same window as the simulation!

I would greatly appreciate it if someone could share their solution, if they have one, to this particular problem.  I hope I have provided enough information.

Thank you!

[Bruce Sherwood]

It would be very helpful if you would post a simple working code fragment to illustrate your questions, as I'm not sure what your question is.

I will however volunteer that in Classic VPython, which you are using, label text must be a character string, not a numeric value. You can produce a character string using the "format" method for Python strings. For example, the following statement

            label(text="There are {} apples".format(17))

displays "There are 17 apples".

In GlowScript VPython and Jupyter VPython, but not in Classic VPython, the label object detects a numerical value, so that

            label(text=3+5)

display "8".

In all versions of VPython, if you want to change the existing text, do this:

L = label(text="Begin")

.....

L.text = "End"  # this changes the text of the existing label object.

If on the other hand you execute

label(text="Begin")

.....

label(text="End")

you will have created two separate label objects, and you will see a confused image if they have the same position.

[Tyler Meehleib]

My problem is solved.  Thank you very much, sir!

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