`TypeError : len() of unsized object` at algorithm_postsimulation.py:108

[fdobad]

A len() of numpy.loadtxt() instance fails.
numpy version : '2.3.5'

diagnostic:

#!python3
from pprint import pprint

import numpy as np

test = {
    "rows": """"simid","cellid"
1,2
3,4
""",
    "row": """"simid","cellid"
1,2
""",
    "empty": "",
    "halfsemicolon": """"simid","cellid"
1,
""",
    "half": """"simid","cellid"
1
""",
}
pprint(test)

for k, v in test.items():
    print(f"--- {k} ---")
    open(k, "w").write(v)
    try:
        data = np.loadtxt(k, delimiter=",", skiprows=1, usecols=[0, 1], dtype=[("sim", np.int32), ("cellid", np.int32)])
    except Exception as e:
        print(f"error loading: {e}")
        continue

    if hasattr(data, "size"):
        print(f"size: {data.size}")
    if hasattr(data, "__len__"):
        try:
            print(f"len: {len(data)}")
        except Exception as e:
            if e is TypeError("len() of unsized object"):
                print(e.__traceback__)
            else:
                print("issue getting len()")

yields:

--- rows ---
size: 2
len: 2
--- row ---
size: 1
issue getting len()
--- empty ---
<ipython-input-36-c2f322146b24>:5: UserWarning: loadtxt: input contained no data: "empty"
  data = np.loadtxt(k, delimiter=",", skiprows=1, usecols=[0, 1], dtype=[("sim", np.int32), ("cellid", np.int32)])
size: 0
len: 0
--- halfsemicolon ---
error loading: could not convert string '' to int32 at row 0, column 2.
--- half ---
error loading: invalid column index 1 at row 1 with 1 columns