Task.read has inconsistent return type between normal AI and power channels - Githubissues

ni / nidaqmx-python

A Python API for interacting with NI-DAQmx

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Task.read has inconsistent return type between normal AI and power channels #527

Open bkeryan opened 6 months ago

bkeryan commented 6 months ago

For normal AI channels, leaving samples_to_read unset reduces the dimensions of the resulting list:

Single channel task:
- task.read() -> scalar
- task.read(1) -> 1D list by sample
- task.read(N) -> 1D list by sample
Multi-channel task:
- task.read() -> 1D list by channel
- task.read(1) -> 2D list by channel, sample
- task.read(N) -> 2D list by channel, sample

However, for power channels, explicitly setting samples_to_read=1 has the same effect:

Single channel task:
- task.read() -> scalar
- task.read(1) -> scalar
- task.read(N) -> 1D list by sample
Multi-channel task:
- task.read() -> 1D list by channel
- task.read(1) -> 1D list by channel
- task.read(N) -> 2D list by channel, sample

Passing samps_per_chan=1 to task.read() returns a different data type, which may cause errors for programs that don't expect that to happen.