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REF: check can_hold_element instead of try/except #27298

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Merged
merged 2 commits into from
Jul 10, 2019
Merged

REF: check can_hold_element instead of try/except #27298

merged 2 commits into from
Jul 10, 2019

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jbrockmendel
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_can_hold_element is not well-documented, and in local testing it does not match my intution of "we could do self.values[:] = element without raising". But adding two assertions in fillna does work in all the tests:

         # fillna, but if we cannot coerce, then try again as an ObjectBlock
        try:
            # equivalent: self._try_coerce_args(value) would not raise
            # Note: we only call try_coerce_args to let it raise
            self._try_coerce_args(value)
            assert self._can_hold_element(value)
        except (TypeError, ValueError): 
            assert not self._can_hold_element(value)

(at least after patching the DatetimeBlock and TimedeltaBlock implementations)

@jbrockmendel
Patch can_hold_element TimedeltaBlock and DatetimeBlock
0e60b5c 
Confirm that the try/except behavior for fillna is equivalent to checking _can_hold_element
@jbrockmendel
Change try/except to can_hold_element check
eb6eaae
jreback
jreback approved these changes Jul 9, 2019
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pandas/core/internals/blocks.py
@@ -2275,7 +2271,13 @@ def _can_hold_element(self, element):
tipo = maybe_infer_dtype_type(element)
if tipo is not None:
return tipo == _NS_DTYPE or tipo == np.int64
return is_integer(element) or isinstance(element, datetime) or isna(element)
if isinstance(element, datetime):
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in followup, can you make these elif

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Sure

pandas/core/internals/blocks.py
@@ -2627,6 +2629,8 @@ def _can_hold_element(self, element):
tipo = maybe_infer_dtype_type(element)
if tipo is not None:
return issubclass(tipo.type, (np.timedelta64, np.int64))
if element is NaT:
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same

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though maybe just add this one below on 2634

@jreback jreback added Clean Internals Related to non-user accessible pandas implementation labels Jul 9, 2019
@jreback jreback added this to the 0.25.0 milestone Jul 9, 2019
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jreback commented Jul 9, 2019

if you can update to those comments, otherwise lgtm.

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Follow up coming shortly, let’s make elif change there

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@jreback gentle ping for this and #27229; next-steps in the works for both of these

@jreback jreback merged commit 823af76 into pandas-dev:master Jul 10, 2019
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jreback commented Jul 10, 2019

thanks @jbrockmendel if you can do those followups in next PRs

@jbrockmendel jbrockmendel deleted the tryless branch July 10, 2019 16:26
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