icexelloss commented on code in PR #35514:
URL: https://github.com/apache/arrow/pull/35514#discussion_r1213365848
##########
python/pyarrow/conftest.py:
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@@ -278,3 +278,59 @@ def unary_function(ctx, x):
{"array": pa.int64()},
pa.int64())
return unary_function, func_name
+
+
[email protected](scope="session")
+def unary_agg_func_fixture():
+ """
+ Register a unary aggregate function
+ """
+ from pyarrow import compute as pc
+ import numpy as np
+
+ def func(ctx, x):
+ return pa.scalar(np.nanmean(x))
+
+ func_name = "y=avg(x)"
+ func_doc = {"summary": "y=avg(x)",
+ "description": "find mean of x"}
+
+ pc.register_aggregate_function(func,
+ func_name,
+ func_doc,
+ {
+ "x": pa.float64(),
+ },
+ pa.float64()
+ )
+ return func, func_name
+
+
[email protected](scope="session")
+def varargs_agg_func_fixture():
+ """
+ Register a unary aggregate function
+ """
+ from pyarrow import compute as pc
+ import numpy as np
+
+ def func(ctx, *args):
+ sum = 0.0
+ for arg in args:
+ sum += np.nanmean(arg)
+ return pa.scalar(sum)
+
+ func_name = "y=sum_mean(x...)"
+ func_doc = {"summary": "Varargs aggregate",
+ "description": "Varargs aggregate"}
+
+ pc.register_aggregate_function(func,
+ func_name,
+ func_doc,
+ {
+ "x": pa.int64(),
+ "y": pa.float64()
Review Comment:
Admittedly this is weird/confusing but here is why:
This not a truely "varargs" function, as this function must take two
arguments x and y with the specified type.
This test case matches how we would this it internally. The end user would
define sth like
```
def foo(x: pd.Series, y: pd.Series):
return np.nanmean(x) + np.nanmean(y)
summarize(table, agg=foo, columns=['x', 'y'], by='time')
```
We would then wrap the foo into a function that Acero is expecting (a
varargs UDF)
```
def get_acero_func(func):
# This wraps turns the func to what Acero is expecting
def acero_func(ctx, *args):
return pa.scalar(func(*[arg.to_pandas() for arg in args]))
return acero_func
```
And also register it in Acero on the fly.
In other words, this is a function with known number of inputs (x, y in this
case) but has function signature that takes `*args` which always have args x
and y.
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