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Improve to_dask_dataframe performance #7844

Merged
merged 5 commits into from
May 25, 2023
Merged

Improve to_dask_dataframe performance #7844

merged 5 commits into from
May 25, 2023

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Illviljan
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@Illviljan Illviljan commented May 15, 2023 •
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  • ds.chunks loops all the variables, do it once.
  • Faster to create a meta dataframe once than letting dask guess 2000 times.

@Illviljan Illviljan mentioned this pull request May 15, 2023
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@Illviljan Illviljan added the run-benchmark Run the ASV benchmark workflow label May 16, 2023
dcherian
dcherian reviewed May 18, 2023
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xarray/core/dataset.py Outdated
@@ -6422,8 +6429,13 @@ def to_dask_dataframe(
if not is_duck_dask_array(var._data):
var = var.chunk()

dask_array = var.set_dims(ordered_dims).chunk(self.chunks).data
series = dd.from_array(dask_array.reshape(-1), columns=[name])
if has_many_dims:
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Is this really that impactful, can we optimize set_dims instead?

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I'll think I'll save the has_many_dims paths for a future PR. I think it might introduce bugs if we don't consistently chunk with the same shape.

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Illviljan commented May 21, 2023 •
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        before           after         ratio
     [05c7888d]       [d135ab97]
-      2.47±0.02s          806±6ms     0.33  pandas.ToDataFrameDask.time_to_dataframe

@Illviljan Illviljan added the plan to merge Final call for comments label May 24, 2023
@Illviljan Illviljan merged commit 609a901 into pydata:main May 25, 2023
@dcherian dcherian mentioned this pull request Jun 15, 2023
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dstansby pushed a commit to dstansby/xarray that referenced this pull request Jun 28, 2023
@Illviljan @dstansby
Improve to_dask_dataframe performance (pydata#7844)
9cb0bdb 
* Improve to_dask_dataframe performance

* Add ASV test

* Update pandas.py

* Update dataset.py
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@Illviljan @dcherian