zhengruifeng commented on code in PR #48105:
URL: https://github.com/apache/spark/pull/48105#discussion_r1758655551
##########
python/pyspark/pandas/plot/core.py:
##########
@@ -68,19 +68,52 @@ class SampledPlotBase:
def get_sampled(self, data):
from pyspark.pandas import DataFrame, Series
+ if not isinstance(data, (DataFrame, Series)):
+ raise TypeError("Only DataFrame and Series are supported for
plotting.")
+ if isinstance(data, Series):
+ data = data.to_frame()
+
fraction = get_option("plotting.sample_ratio")
- if fraction is None:
- fraction = 1 / (len(data) / get_option("plotting.max_rows"))
- fraction = min(1.0, fraction)
- self.fraction = fraction
-
- if isinstance(data, (DataFrame, Series)):
- if isinstance(data, Series):
- data = data.to_frame()
+ if fraction is not None:
+ self.fraction = fraction
sampled =
data._internal.resolved_copy.spark_frame.sample(fraction=self.fraction)
return DataFrame(data._internal.with_new_sdf(sampled))._to_pandas()
else:
- raise TypeError("Only DataFrame and Series are supported for
plotting.")
+ from pyspark.sql import Observation
+
+ max_rows = get_option("plotting.max_rows")
+ observation = Observation("ps plotting")
+ sdf = data._internal.resolved_copy.spark_frame.observe(
+ observation, F.count(F.lit(1)).alias("count")
+ )
+
+ rand_col_name = "__ps_plotting_sampled_plot_base_rand__"
+ id_col_name = "__ps_plotting_sampled_plot_base_id__"
+
+ sampled = (
+ sdf.select(
+ "*",
+ F.rand().alias(rand_col_name),
+ F.monotonically_increasing_id().alias(id_col_name),
+ )
+ .sort(rand_col_name)
+ .limit(max_rows + 1)
+ .coalesce(1)
+ .sortWithinPartitions(id_col_name)
Review Comment:
using local sorting to avoid unnecessary shuffle
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