This looks like something to improve in the Python bindings. Would you like to open a JIRA issue about it?
On Tue, Oct 6, 2020 at 4:26 AM Kirill Lykov <[email protected]> wrote: > > Hi, > > I'm trying to write a code in python which executes an expression on > filtered data. So I create a filter and later projector for some expression > but don't get how to combine those two in python: > > ```python > import pyarrow as pa > import pyarrow.gandiva as gandiva > > table = pa.Table.from_arrays([pa.array([1., 31., 46., 3., 57., 44., 22.]), > pa.array([5., 45., 36., 73., > 83., 23., 76.])], > ['a', 'b']) > > builder = gandiva.TreeExprBuilder() > node_a = builder.make_field(table.schema.field("a")) > node_b = builder.make_field(table.schema.field("b")) > fifty = builder.make_literal(50.0, pa.float64()) > eleven = builder.make_literal(11.0, pa.float64()) > > cond_1 = builder.make_function("less_than", [node_a, fifty], pa.bool_()) > cond_2 = builder.make_function("greater_than", [node_a, node_b], > pa.bool_()) > cond_3 = builder.make_function("less_than", [node_b, eleven], pa.bool_()) > cond = builder.make_or([builder.make_and([cond_1, cond_2]), cond_3]) > condition = builder.make_condition(cond) > > filter = gandiva.make_filter(table.schema, condition) > # filterResult has type SelectionVector > filterResult = filter.evaluate(table.to_batches()[0], > pa.default_memory_pool()) > print(result) > > sum = builder.make_function("add", [node_a, node_b], pa.float64()) > field_result = pa.field("c", pa.float64()) > expr = builder.make_expression(sum, field_result) > projector = gandiva.make_projector( > table.schema, [expr], pa.default_memory_pool()) > > ### Here there is a problem that I don't know how to use filterResult with > projector > r, = projector.evaluate(table.to_batches()[0], result) > ``` > > In C++, I see that it is possible to pass SelectionVector as second > argument to projector::Evaluate: > https://github.com/apache/arrow/blob/c5fa23ea0e15abe47b35524fa6a79c7b8c160fa0/cpp/src/gandiva/tests/filter_project_test.cc#L270 > > Meanwhile, it looks like it is impossible in `gandiva.pyx`: > https://github.com/apache/arrow/blob/a4eb08d54ee0d4c0d0202fa0a2dfa8af7aad7a05/python/pyarrow/gandiva.pyx#L154 > > > > -- > Best regards, > Kirill Lykov
