ValueError: buffer source array is read-only · Issue #31710 · pandas-dev/pandas (original) (raw)

Code Sample, a copy-pastable example if possible

index = pd.date_range('2020', 'now', freq='1h') arr = np.zeros_like(index) arr.setflags(write=False) pd.Series(arr, index=index).resample('1d').agg('last')

~/pandas/pandas/_libs/groupby.pyx in pandas._libs.groupby.group_last() ~/pandas/pandas/_libs/groupby.cpython-37m-x86_64-linux-gnu.so in View.MemoryView.memoryview_cwrapper() ~/pandas/pandas/_libs/groupby.cpython-37m-x86_64-linux-gnu.so in View.MemoryView.memoryview.cinit() ValueError: buffer source array is read-only

Problem description

Groupby fails on some read-only buffers (I couldn't quickly reproduce it with .groupby() itself, sorry).

The prime solution would be to add const specifier to the input values here (and related entries):

if it were not for Cython's non-support of const fused types (cython/cython#1772), resolved in (cython/cython#3118), but despite miniscule change only scheduled for release in Cython 3.0. I guess wait until then.

Expected Output

Resampling/groupby works with read-only arrays.

Output of pd.show_versions()

pandas 1.1.0.dev0+361.gf0b00f887
cython 0.29.14