numpy deprecation warning for .tostring()

[pfbuxton]

Hello,

Numpy is warning that .tostring() is a deprecated.

Here is the warning:

  /tmp/mdsplus-stable/python/MDSplus/mdsscalar.py:437: DeprecationWarning: tostring() is deprecated. Use tobytes() instead.
    return cls(_N.array(_C.cast(d.pointer, _C.POINTER((_C.c_byte*d.length))).contents[:], dtype=_N.uint8).tostring())

the line which is causing the issue is here: mdsscalar.py#L437.

I am using:

numpy                           1.24.3
MDSplus                         7.132.0

Here is the numpy documentation, which states "Despite its name, it returns bytes not strs.", so it's not surprising that it has been deprecated, and changing to tobytes() should produce exactly the same results.

[mwinkel-dev]

This issue from Tokamak Energy is probably on the stable branch (implied by version 7.132.0 listed in the bug report).

Was able to replicate the problem on Ubuntu 20.04 using a current build of MDSplus alpha (~7.139.17), numpy 1.24.3, python 3.8.10 and PYTHONWARNINGS=default. And also confirmed that replacing tostring() with tobytes() eliminates the warning. Will submit a PR soon.

[mwinkel-dev]

And here is an example of how to trigger the warning.

#
# Simple program to illustrate Issue #2589.
# Install NumPy 1.19.0 or later.
# And set environment variable PYTHONWARNINGS=default.
#

import MDSplus as mds

# This refers to a C-Mod shot and subtree
shot = 1160422016
tree = mds.Tree("engineering", shot)

node = tree.getNode("cryo_plc.after:EF1L_RC")
data = node.getData()

print()

# This statement triggers the warning about tostring() being deprecated
print("data = ", data)

print("type = ", type(data))
print()

[pfbuxton]

Great to hear that you were able to replicate the issue!