BUG: Fix replace for different dtype equal value

[dsaxton]

Bug noticed when looking at a different issue #34871 (comment)

• closes BUG: inconsistent replace #35376
• tests added / passed
• passes black pandas
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

[jreback]

we only want to do this if these are different types, not generally. please show asv's for this.

[dsaxton]

I think the if not self._can_hold_element(to_replace) check is making sure we have different types.

Not seeing any performance regressions from the change (at least in the replace benchmarks):

(pandas-dev) > asv continuous -f 1.1 upstream/master replace-diff-dtype -b ^replace · Creating environments · Discovering benchmarks ·· Uninstalling from conda-py3.7-Cython0.29.16-matplotlib-numba-numexpr-numpy-odfpy-openpyxl-pytables-pytest-scipy-sqlalchemy-xlrd-xlsxwriter-xlwt. ·· Installing 1e014777 <replace-diff-dtype> into conda-py3.7-Cython0.29.16-matplotlib-numba-numexpr-numpy-odfpy-openpyxl-pytables-pytest-scipy-sqlalchemy-xlrd-xlsxwriter-xlwt.. · Running 12 total benchmarks (2 commits * 1 environments * 6 benchmarks) [ 0.00%] · For pandas commit 9114b4bc <master> (round 1/2): [ 0.00%] ·· Building for conda-py3.7-Cython0.29.16-matplotlib-numba-numexpr-numpy-odfpy-openpyxl-pytables-pytest-scipy-sqlalchemy-xlrd-xlsxwriter-xlwt... [ 0.00%] ·· Benchmarking conda-py3.7-Cython0.29.16-matplotlib-numba-numexpr-numpy-odfpy-openpyxl-pytables-pytest-scipy-sqlalchemy-xlrd-xlsxwriter-xlwt [ 4.17%] ··· Running (replace.Convert.time_replace--).... [ 20.83%] ··· Running (replace.ReplaceList.time_replace_list--).. [ 25.00%] · For pandas commit 1e014777 <replace-diff-dtype> (round 1/2): [ 25.00%] ·· Building for conda-py3.7-Cython0.29.16-matplotlib-numba-numexpr-numpy-odfpy-openpyxl-pytables-pytest-scipy-sqlalchemy-xlrd-xlsxwriter-xlwt... [ 25.00%] ·· Benchmarking conda-py3.7-Cython0.29.16-matplotlib-numba-numexpr-numpy-odfpy-openpyxl-pytables-pytest-scipy-sqlalchemy-xlrd-xlsxwriter-xlwt [ 29.17%] ··· Running (replace.Convert.time_replace--).... [ 45.83%] ··· Running (replace.ReplaceList.time_replace_list--).. [ 50.00%] · For pandas commit 1e014777 <replace-diff-dtype> (round 2/2): [ 50.00%] ·· Benchmarking conda-py3.7-Cython0.29.16-matplotlib-numba-numexpr-numpy-odfpy-openpyxl-pytables-pytest-scipy-sqlalchemy-xlrd-xlsxwriter-xlwt [ 54.17%] ··· replace.Convert.time_replace ok [ 54.17%] ··· ============= ============ ============ -- replace_data ------------- ------------------------- constructor Timestamp Timedelta ============= ============ ============ DataFrame 98.6±3ms 95.2±0.5ms Series 74.0±0.3ms 74.6±1ms ============= ============ ============ [ 58.33%] ··· replace.FillNa.time_fillna ok [ 58.33%] ··· ========= ============= inplace --------- ------------- True 1.04±0.01ms False 3.01±0.3ms ========= ============= [ 62.50%] ··· replace.FillNa.time_replace ok [ 62.50%] ··· ========= ============= inplace --------- ------------- True 1.10±0.02ms False 4.02±0.07ms ========= ============= [ 66.67%] ··· replace.ReplaceDict.time_replace_series ok [ 66.67%] ··· ========= ============ inplace --------- ------------ True 4.27±0.02s False 4.24±0.04s ========= ============ [ 70.83%] ··· replace.ReplaceList.time_replace_list ok [ 70.83%] ··· ========= ============ inplace --------- ------------ True 51.6±0.6μs False 405±5ms ========= ============ [ 75.00%] ··· replace.ReplaceList.time_replace_list_one_match ok [ 75.00%] ··· ========= ========== inplace --------- ---------- True 89.2±3ms False 467±4ms ========= ========== [ 75.00%] · For pandas commit 9114b4bc <master> (round 2/2): [ 75.00%] ·· Building for conda-py3.7-Cython0.29.16-matplotlib-numba-numexpr-numpy-odfpy-openpyxl-pytables-pytest-scipy-sqlalchemy-xlrd-xlsxwriter-xlwt... [ 75.00%] ·· Benchmarking conda-py3.7-Cython0.29.16-matplotlib-numba-numexpr-numpy-odfpy-openpyxl-pytables-pytest-scipy-sqlalchemy-xlrd-xlsxwriter-xlwt [ 79.17%] ··· replace.Convert.time_replace ok [ 79.17%] ··· ============= =========== =========== -- replace_data ------------- ----------------------- constructor Timestamp Timedelta ============= =========== =========== DataFrame 102±4ms 103±3ms Series 80.0±4ms 83.1±4ms ============= =========== =========== [ 83.33%] ··· replace.FillNa.time_fillna ok [ 83.33%] ··· ========= ============= inplace --------- ------------- True 1.10±0.04ms False 3.04±0.1ms ========= ============= [ 87.50%] ··· replace.FillNa.time_replace ok [ 87.50%] ··· ========= ============= inplace --------- ------------- True 1.20±0.04ms False 4.26±0.2ms ========= ============= [ 91.67%] ··· replace.ReplaceDict.time_replace_series ok [ 91.67%] ··· ========= ============ inplace --------- ------------ True 4.26±0.01s False 4.24±0.01s ========= ============ [ 95.83%] ··· replace.ReplaceList.time_replace_list ok [ 95.83%] ··· ========= ========== inplace --------- ---------- True 49.6±1μs False 412±6ms ========= ========== [100.00%] ··· replace.ReplaceList.time_replace_list_one_match ok [100.00%] ··· ========= ========== inplace --------- ---------- True 89.3±2ms False 464±30ms ========= ========== BENCHMARKS NOT SIGNIFICANTLY CHANGED. 

[jreback]

can u merge master and will look

[simonjayhawkins]

@dsaxton can you move release note

[simonjayhawkins]

marking as stale 😉

[jreback]

can you move to 1.2

[simonjayhawkins]

this looks similar to regression reported in #35376 with open PR (with different fix) #36444

[dsaxton]

Yeah I think it's the same issue. If another fix avoids astyping to object I would think it's preferred.

[dsaxton]

Closing since the other PR looks like a better fix