Bug Report

Steps to Reproduce:

1. Open .arrow file by pyarrow RecordBatchFileReader
2. Create perspective Table from the file
3. Host table by PerspectiveManager
4. Call perspectiveViewer.load(websocket.open_table("table_name")) in browser
5. Change visualization plugin to Datagrid

Expected Result:

Changing perspective-viewer plugin to Datagrid

Actual Result:

I get this error from server side:

get_data_slice_zero(): incompatible function arguments.
The following argument types are supported:    1. (arg0: perspective.table.libbinding.View_ctx0, arg1: int, arg2: int, arg3: int, arg4: int) -> perspective.table.libbinding.t_data_slice_ctx0Invoked
with: <perspective.table.libbinding.View_ctx0 object at 0x000002B5805A3F70>, 0, 40.78947368421053, 0, 1

Another plugins, including Hypergrid, work as expected

On node.js server with the same data file all works as expected

Client's message from websocket pipe that cause the error:

{"cmd":"view_method","name":"0.720999804799138","method":"to_columns","args":[{"start_col":0,"end_col":2,"start_row":0,"end_row":40.473684210526315,"id":false}],"subscribe":false,"id":248}

and answer of server is:

{"id": 248, "error": "get_data_slice_zero(): incompatible function arguments. The following argument types are supported:\n    1. (arg0: perspective.table.libbinding.View_ctx0, arg1: int, arg2: int, arg3: int, arg4: int) -> perspective.table.libbinding.t_data_slice_ctx0\n\nInvoked with: <perspective.table.libbinding.View_ctx0 object at 0x000001DF8F092130>, 0, 40.473684210526315, 0, 2"}

Should end_row in client's message be integer rather than float?

Environment:

Windows 10.0.18363
python 3.7.8
perspective-python 0.5.1

Schema of my arrow file:

{'index': <class 'int'>, 'gbuName': <class 'str'>, 'periodName': <class 'str'>, 'ind': <class 'str'>, 'indName': <class 'str'>, 'values': <class 'float'>, 'Y': <class 'str'>}