Python lists/arrays cannot be cast in Deephaven tables

[jjbrosnan]

Description

An error occurs when attempting to cast a list in Python (whether it be a generic list, NumPy list, etc) to a particular list type in Java.

Steps to reproduce

The following code will produce an error:

from deephaven.TableTools import emptyTable

a = [1, 2, 3]

t = emptyTable(1).update("x = a")
t2 = emptyTable(2).update("x = (int[])a")

Expected results

A one-row table (t) with a list of integers in the x column as a PyObject displayed as a string. Another one-row table (t2) with a list of integers in the x column displayed as a list in Java.

Actual results

An error

Additional details and attachments

Attempting to cast to an int also doesn't work (which is expected).

Versions

• Deephaven: OSS
• OS: Big Sur
• Browser: Chrome
• Docker: 20.10.8

[jjbrosnan]

As of 01/31/2022, this bug is still present. It would be great to cast a Python list to the Java list of the corresponding type, just like with primitives. With content on the horizon regarding higher-dimensional tensors (MNIST with Deephaven?), this bug need to be addressed in order to move forward.