Sending multiple Named Values at once

[AkaMrBill]

In a PM I recently had with @virtuald, he mentioned that there currently is not a mechanism to send multiple named values at once. For example: X, Y, Distance, Time, area; from a vision tracking coprocessor.
So, for this discussion, how can multiple values be handled at one time, and is this a process that may be added in the future?

I have read and heard that numpy arrays may be a current solution. OK, makes sense, but as a "Hobby Hacker" I usually need examples to help me figure out how to do that. Are any available?

[Starlight220]

The solution that PhotonVision (@Bankst) uses is encoding those values into an array, which the PhotonLib API then decodes.

[AkaMrBill]

Thanks @TheTripleV, that is the direction I would like to go.
This code will be running on an RPi and be written in Python. The robot will be running Java, well, at least for my test case. In fact, my "NetworkTables robot simulator" is on a Windows workstation and runs Python, but this is just my test environment. My goal is to have this send to NetworkTables on a standard RoboRio setup.
So, I guess my question is: Is there sample code I can look at to see how the tracking parameters are packaged into a Numpy Array and then sent via xx.putNumberArray ?

[virtuald]

Here's a silly example:

e = NetworkTables.getEntry("/SmartDashboard/myarray")

i = 0
while True:
    e.setNumberArray([i, i*2])
    print(e)
    time.sleep(1)
    i += 1

[AkaMrBill]

@virtuald, thanks!
So, if I'm understanding this correctly, this is just putting an array into the networktable? No names, just values, correct? My understanding is, mixing datatypes in a numpy array is a bad idea, so this avoids that issue.

To slightly extend your example to my project, I could do this:

vs = NetworkTables.getEntry("Vision/myArray")

while 1:
##Image processing goes here
    x = 125
    y = 145
    dist = 121
    vs.setNumberArray([x, y, dist])

Now would this work as well, and would it populate NetworkTables correctly, or would it also need to be parsed out on the server to populate the individual table entries:

vs = NetworkTables.getEntry("Vision/myArray")

while 1:
##Image processing goes here
    x = 125
    y = 145
    dist = 121
    vs.putNumberArray([("X",x),("Y", y),("Distance", dist)])

Sorry, my Python skills are rudimentary at best, so I'm just trying to learn and understand.

[Starlight220]

putNumberArray sends specifically an array of numbers, you can't send tuples with it. If you want to populate different entries then you should set each entry on itself, but once again--you would have no assurances about synchronization between different entries.

[AkaMrBill]

Got it.

OK, one more question then.
Using xx.putNumber("Name", value) simply adds/updates the key on the local instance of NetworkTables, then NetworkTables handles copying those to the server, correct? If so, is there a set interval that the copying takes place?

[edit] I think I just answered my own question, at least for PyNetworkTables.
https://robotpy.readthedocs.io/projects/pynetworktables/en/stable/api.html [/edit]