leewyang commented on code in PR #37734:
URL: https://github.com/apache/spark/pull/37734#discussion_r970164323
##########
python/pyspark/ml/functions.py:
##########
@@ -106,6 +111,167 @@ def array_to_vector(col: Column) -> Column:
return
Column(sc._jvm.org.apache.spark.ml.functions.array_to_vector(_to_java_column(col)))
+def batched(df: pd.DataFrame, batch_size: int = -1) -> Iterator[pd.DataFrame]:
+ """Generator that splits a pandas dataframe/series into batches."""
+ if batch_size <= 0 or batch_size >= len(df):
+ yield df
+ else:
+ # for batch in np.array_split(df, (len(df.index) + batch_size - 1) //
batch_size):
+ for _, batch in df.groupby(np.arange(len(df)) // batch_size):
+ yield batch
+
+
+def has_tensor_cols(df: pd.DataFrame) -> bool:
+ """Check if input DataFrame contains any tensor-valued columns"""
+ if any(df.dtypes == np.object_):
+ # pd.DataFrame object types can contain different types, e.g. string,
dates, etc.
+ # so inspect a row and check for array/list type
+ sample = df.iloc[0]
+ return any([isinstance(x, np.ndarray) or isinstance(x, list) for x in
sample])
+ else:
+ return False
+
+
+def batch_infer_udf(
+ predict_batch_fn: Callable,
+ return_type: DataType = ArrayType(FloatType()),
+ batch_size: int = -1,
+ input_names: list[str] = [],
+ input_tensor_shapes: list[list[int]] = [],
+ **kwargs: Any,
+) -> Callable:
+ """Given a function which loads a model, returns a pandas_udf for
inferencing over that model.
+
+ This will handle:
+ - conversion of the Spark DataFrame to numpy arrays.
+ - batching of the inputs sent to the model predict() function.
+ - caching of the model and prediction function on the executors.
+
+ This assumes that the `predict_batch_fn` encapsulates all of the necessary
dependencies for
+ running the model or the Spark executor environment already satisfies all
runtime requirements.
+
+ When selecting columns in pyspark SQL, users are required to always use
`struct` for simplicity.
+
+ For the conversion of Spark DataFrame to numpy, the following table
describes the behavior,
+ where tensor columns in the Spark DataFrame must be represented as a
flattened 1-D array/list.
+
+ | dataframe \\ model | single input | multiple inputs |
+ | :----------------- | :----------- | :-------------- |
+ | single-col scalar | 1 | N/A |
+ | single-col tensor | 1,2 | N/A |
+ | multi-col scalar | 3 | 4 |
+ | multi-col tensor | N/A | 4,2 |
+
+ Notes:
+ 1. pass thru dataframe column => model input as single numpy array.
+ 2. reshape flattened tensors into expected tensor shapes.
+ 3. convert entire dataframe into single numpy array via df.to_numpy(), or
user can use
+ `pyspark.sql.functions.array()` to transform the input into a
single-col tensor first.
+ 4. pass thru dataframe column => model input as an (ordered) dictionary of
numpy arrays.
+
+ Parameters
+ ----------
+ predict_batch_fn : Callable
+ Function which is responsible for loading a model and returning a
`predict` function.
+ return_type : :class:`pspark.sql.types.DataType` or str.
+ Spark SQL datatype for the expected output.
+ Default: ArrayType(FloatType())
+ batch_size : int
+ Batch size to use for inference, note that this is typically a
limitation of the model
+ and/or the hardware resources and is usually smaller than the Spark
partition size.
+ Default: -1, which sends the entire Spark partition to the model.
Review Comment:
Ended up just making it a required param for now.
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