Python support

[Ryanforce08]

When downloading lib from pypi nothing can be imported from lib

[JaciBrunning]

Hi, there is content within the library - it's just intellisense for the package is not functioning. You should be able to import the packages as follows:

from libgrapplefrc import LaserCAN

my_lasercan = LaserCAN(0)
my_lasercan.get_measurement()

[Ryanforce08]

Sadly that did not work. Is there suppost to be more in the lib then just this?

[JaciBrunning]

That's what it should look like - the python init is just a wrapper around a native implementation. The actual code is the same library that the Java and C++ versions depend on so we can keep the library common.

[Ryanforce08]

Sorry for late reply but I did get it to work so thanks for your help. I also just wanted to let you know that I found a way to fix the autofill issue. Currently it's just a wrapper for it but I can make a pull request to implement it in the lib if you would like. https://github.com/FRC5113/LemonLib/tree/main/lemonlib/grapple

[JaciBrunning]

Looks good, PRs always welcome :)

[warres1212]

I am having the same issue as Ryanforce08. The library is installed, but I can’t import the library. I am not sure how to resolve the issue. Sorry if I missed how to resolve the issue I am not a very experienced programmer.

lasercan_subsystem.py

import commands2
import libgrapplefrc
import constants
import wpilib
from wpilib import SmartDashboard
from libgrapplefrc import LaserCAN

class LaserCANSubsystem(commands2.Subsystem):
"""
A subsystem for the Grapple Robotics LaserCAN sensor.
"""
def init(self, can_id):
super().init()
self.lc = LaserCAN(constants.lasercan_id)
self.lc.setRange(0) #0 = kShort setRangingMode()
self.lc.setRegionOfInterest(8,8,16,16) #setRoi()
self.last_range = 0.0

def getLaserCanDistance(self):
    """returns the distance from the laserCAN in millimeters"""
    measurement = self.lc.get_measurement() #getMeasurement()
    #meas_sigma = self.lc.getRangeSigma()
    #print(f"lc measurement is {measurement}")
    if (measurement != None and self.lc.getStatus() == 0): #0 = kValid
        return measurement #distance in mm
    else:
        return 1000
    
def get_distance_mm(self) -> float:
    """
    Get the distance from the LaserCAN sensor in millimeters.
    """
    # Use getRange() to get the distance.
    range_mm = self.lc.get_measurement()  #getMeasurement()
    #print(f"lc_range is {range_mm}")
    # Check for valid status before returning the value.
    if (range_mm != None and self.lc.getStatus() == 0):
        self.last_range = range_mm
        return self.last_range
    else:
        return 1000

def periodic(self):
    """
    This method is called periodically by the CommandScheduler.
    """
    # We can add a periodic printout to see the distance in real-time.
    distance = self.get_distance_mm()
    wpilib.SmartDashboard.putNumber("Get Distance (mm)", distance)
    wpilib.SmartDashboard.putNumber("LaserCAN Distance (mm)", self.getLaserCanDistance())
    print(self.lc.get_measurement.__doc__)

[JaciBrunning]

Hi @warres1212 , what's the exact error message that you're getting when you try to import?

Also, you can include code in a block by surrounding it with ``` (gives better formatting)

[Ryanforce08]

I am now realizing that I never made that pr. When I get home I can and that should fix your problem. Until then you can use the wrapper I made for it on the link I sent above.

[warres1212]

I uploaded my project to GitHub for reference (https://github.com/warres1212/test_laser_can_range.git).
I was not seeing any errors, the grapple device was not making any measurements.
Ryanforce08, I am not sure how to use a wrapper? Can you direct me to information on what a wrapper is and how to use it?

Thanks,
Steve

[warres1212]

So I just need to add the grapple folder into my project? I don’t have a MitoCANdria, can I delete those lines? Also the folder py.touch has no content, is that folder required? Sorry for all the questions, I am not a programmer. Just trying to learn.

[warres1212]

@JaciBrunning, any thoughts on why the contents of the library are not available in robotpy? Is this only an issue with robotpy? What do I need to change to make the Grapple LaserCan work correctly?

[Ryanforce08]

Sorry for late reply. You wanna install the actual lib and then copy and paste the grapple file and import that in code. I'm working on a better version cause I just threw this together to test our laser can out.

[warres1212]

@Ryanforce08 - Sorry, I am not an experienced programmer and just started trying to write code in Python. To be specific, I copy the contents of “LemonLib/lemonlib” into my “…/site-packages” directory (macOS). Then I need to add “lemonlib” to the “pyproject.toml”

pyproject.toml
[tool.robotpy]

Version of robotpy this project depends on

robotpy_version = "2025.3.2.2"

Which extra RobotPy components should be installed

-> equivalent to `pip install robotpy[extra1, ...]

robotpy_extras = [
"lemonlib",
# "all",
# "apriltag",

Then copy the “LemonLib/lemonlib/grapple” folder to my project folder.
I am not clear on how I need to update my code to use the new library and grapple code after performing a “sync”. Any help would be appreciated. Thanks for your patience.

[Ryanforce08]

Sorry for very late reply again. Until we start using pypi just copy and paste the lemonlib folder into your root directory or what ever folder robot.py is In and just import like any other lib. Ex : from lemonlib.grapple import LaserCAN

[Ryanforce08]

I also did a pull request to add to this lib to fix the import stuff so if thats accepted you can just use this