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new 95fba869169 [SPARK-39534][PS] Series.argmax only needs single pass
95fba869169 is described below
commit 95fba8691696f6c4c00927cbcd8fde81765f0252
Author: Ruifeng Zheng <ruife...@apache.org>
AuthorDate: Tue Jun 21 08:57:27 2022 +0900
[SPARK-39534][PS] Series.argmax only needs single pass
### What changes were proposed in this pull request?
compute `Series.argmax ` with one pass
### Why are the changes needed?
existing implemation of `Series.argmax` needs two pass on the dataset, the
first one is to compute the maximum value, and the second one is to get the
index.
However, they can be computed on one pass.
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
existing UT
Closes #36927 from zhengruifeng/ps_series_argmax_opt.
Authored-by: Ruifeng Zheng <ruife...@apache.org>
Signed-off-by: Hyukjin Kwon <gurwls...@apache.org>
---
python/pyspark/pandas/series.py | 20 ++++++++------------
1 file changed, 8 insertions(+), 12 deletions(-)
diff --git a/python/pyspark/pandas/series.py b/python/pyspark/pandas/series.py
index 813d27709e4..352e7dd750b 100644
--- a/python/pyspark/pandas/series.py
+++ b/python/pyspark/pandas/series.py
@@ -6301,22 +6301,18 @@ class Series(Frame, IndexOpsMixin, Generic[T]):
scol = scol_for(sdf, self._internal.data_spark_column_names[0])
if skipna:
- sdf = sdf.orderBy(scol.desc_nulls_last(),
NATURAL_ORDER_COLUMN_NAME)
+ sdf = sdf.orderBy(scol.desc_nulls_last(),
NATURAL_ORDER_COLUMN_NAME, seq_col_name)
else:
- sdf = sdf.orderBy(scol.desc_nulls_first(),
NATURAL_ORDER_COLUMN_NAME)
+ sdf = sdf.orderBy(scol.desc_nulls_first(),
NATURAL_ORDER_COLUMN_NAME, seq_col_name)
- max_value = sdf.select(
- F.first(scol),
- F.first(NATURAL_ORDER_COLUMN_NAME),
- ).head()
+ results = sdf.select(scol, seq_col_name).take(1)
- if max_value[1] is None:
+ if len(results) == 0:
raise ValueError("attempt to get argmax of an empty sequence")
- elif max_value[0] is None:
- return -1
-
- # If the maximum is achieved in multiple locations, the first row
position is returned.
- return sdf.filter(scol == max_value[0]).head()[0]
+ else:
+ max_value = results[0]
+ # If the maximum is achieved in multiple locations, the first row
position is returned.
+ return -1 if max_value[0] is None else max_value[1]
def argmin(self) -> int:
"""
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