diff options
Diffstat (limited to 'numpy')
| -rw-r--r-- | numpy/lib/npyio.py | 7 | ||||
| -rw-r--r-- | numpy/lib/tests/test_io.py | 23 |
2 files changed, 30 insertions, 0 deletions
diff --git a/numpy/lib/npyio.py b/numpy/lib/npyio.py index b5723dee5..3b7b3bb30 100644 --- a/numpy/lib/npyio.py +++ b/numpy/lib/npyio.py @@ -1062,6 +1062,13 @@ def _read(fname, *, delimiter=',', comment='#', quote='"', arr = _ensure_ndmin_ndarray(arr, ndmin=ndmin) + if arr.shape[0] == 0: + warnings.warn( + f'loadtxt: input contained no data: "{fname}"', + category=UserWarning, + stacklevel=2 + ) + if unpack: # Handle unpack like np.loadtxt. # XXX Check interaction with ndmin! diff --git a/numpy/lib/tests/test_io.py b/numpy/lib/tests/test_io.py index 7cc1b7ede..4a5cc1ad8 100644 --- a/numpy/lib/tests/test_io.py +++ b/numpy/lib/tests/test_io.py @@ -3242,3 +3242,26 @@ def test_loadtxt_consecutive_quotechar_escaped(): expected = np.array('Hello, my name is "Monty"!', dtype="U40") res = np.loadtxt(txt, dtype="U40", delimiter=",", quotechar='"') assert_equal(res, expected) + + +@pytest.mark.parametrize("data", ("", "\n\n\n", "# 1 2 3\n# 4 5 6\n")) +@pytest.mark.parametrize("ndmin", (0, 1, 2)) +def test_loadtxt_warn_on_no_data(data, ndmin): + """Check that a UserWarning is emitted when no data is read from input.""" + txt = TextIO(data) + with pytest.warns(UserWarning, match="input contained no data"): + np.loadtxt(txt, ndmin=ndmin) + + with NamedTemporaryFile(mode="w") as fh: + fh.write(data) + fh.seek(0) + with pytest.warns(UserWarning, match="input contained no data"): + np.loadtxt(txt, ndmin=ndmin) + + +@pytest.mark.parametrize("skiprows", (2, 3)) +def test_loadtxt_warn_on_skipped_data(skiprows): + data = "1 2 3\n4 5 6" + txt = TextIO(data) + with pytest.warns(UserWarning, match="input contained no data"): + np.loadtxt(txt, skiprows=skiprows) |