polar plot, external index number input?

[teepo]

Hi,

I am having some difficulty feeding one (magnitude, angle) continous stream of data to a polar plot.  How can I select the index number of the array that inputs to the polar vi?

The picture sort of shows what I'm after, but shows only 3 clusters into an array at n = 0 ,1, 2.   Instead, I have a single feed , and I can control the index # indicator based on the angle using some math operators.  How can I input the index #?

Any help is appreciated.

Thanks!

[altenbach]

You would built your data array in a shift register of feedback node.

A "continuous stream" is a poorly defined concept, because ultimately you will run out of memory. A better idea would be to simply graph the last N values for example?

I don't understand your teminology. What do you mean by "index number" in this context? Makes mot much sense. 😉

[teepo]

The magnitude and angle data output stop when it reaches 360 deg.  So the picture 2.jpg is what I have currently, but the data it captured only at array index n=0.

I want to capture:

mag/angle when angle is 0 to array n=0

mag/angle when angle is 15 to array n =1

mag/angle when angle is 30 to array n =2

and so on until angle is 360 (n = 24)

If I have 24 clusters it would be easy to stick those into an array, but I have just 1 cluster where the magnitude and angle continue to change til angle = 360.

I'm not sure if I'm explaining well enough?   Thank you for your response!

[teepo]

Here is my goal, in figure 3.jpg, to be able to control the index # of the array.  So when angle is 0, 0/15 = 0 and index = 0.  When angle is 15, index = 1, etc.  I'm not sure what array function to use to be able to do this. 

[altenbach]

You seem to have a few misunderstanding of arrays and graphical programmings in general. I would recommend to start with a few easy tutorials.

In any case, you have several options, here are two:

• If you want to update the graph after each additional number, you would need to built the array in a feedback node or shift register and place everything in a loop (see A).
• If the data generation is fast, you could do it in a loop, built the array at an autoindexing output tunnel, and graph all at once at the end (see B).

Of course you would need to make sure the values change with each iteration of the loop. Instead of controls (which is silly!), make the values a function of [i], for example.

Message Edited by altenbach on 06-26-2009 11:06 AM

[teepo]

Altenbach  --  Thanks for your help!! I'll give this a try

[altenbach]

Here's an example of a spiral with 15 degree increments.

Message Edited by altenbach on 06-26-2009 11:25 AM

[teepo]

Any chance you can send the vi  ? Thanks again!

[altenbach]

What's your LabVIEW version?

[teepo]

version 8.6