compare does not work for object arrays

When it contains non numeric data (e.g. strings), the maxdiff is 'nan' and thus, you get no colors.

Worse yet, when it does not contain strings but contains zeros it crashes with ZeroDivisionError because np.seterr(divide='ignore', invalid='ignore') has no effect for object arrays. In effect in that case a / b is mostly equal to calling __truediv__ on each cell and this raises ZeroDivisionError: division by zero

Simple test cases:

>>> arr1 = ndtest(3).astype(object)
>>> arr2 = ndtest(3).astype(object)
>>> compare(arr1, arr2)
<snip>
File C:\usr\devel\larray-editor\larray_editor\comparator.py:185, in ComparatorWidget._update_from_combined_array(self)
    183 with np.errstate(divide='ignore', invalid='ignore'):
    184     diff = self._combined_array - self._array0
--> 185     reldiff = diff / self._array0
    186 # make reldiff 0 where the values are the same than array0 even for
    187 # special values (0, nan, inf, -inf)
    188 # at this point reldiff can still contain nan and infs
    189 reldiff = la.where(eq, 0, reldiff)
ZeroDivisionError: division by zero

>>> arr1 = ndtest(3).astype(str)
>>> arr2 = ndtest(3).astype(str)
>>> compare(arr1, arr2)

FIX: compare() for non-numeric arrays (fixes #163)

FIX: compare() for non-numeric arrays (fixes larray-project#163)

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compare does not work for object arrays #163

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compare does not work for object arrays #163

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gdementen commented on Mar 23, 2026

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