wehub-resource-sync
78 lines
3.5 KiB
Markdown
78 lines
3.5 KiB
Markdown
# What is `perspective-python`
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Perspective for Python uses the exact same C++ data engine used by the
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[WebAssembly version](https://docs.rs/perspective-js/latest/perspective_js/) and
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[Rust version](https://docs.rs/crate/perspective/latest). The library consists
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of many of the same abstractions and API as in JavaScript, as well as
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Python-specific data loading support for [NumPy](https://numpy.org/),
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[Pandas](https://pandas.pydata.org/) (and
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[Apache Arrow](https://arrow.apache.org/), as in JavaScript).
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Additionally, `perspective-python` provides a session manager suitable for
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integration into server systems such as
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[Tornado websockets](https://www.tornadoweb.org/en/stable/websocket.html),
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[AIOHTTP](https://docs.aiohttp.org/en/stable/web_quickstart.html#websockets), or
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[Starlette](https://www.starlette.io/websockets/)/[FastAPI](https://fastapi.tiangolo.com/advanced/websockets/),
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which allows fully _virtual_ Perspective tables to be interacted with by
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multiple `<perspective-viewer>` in a web browser. You can also interact with a
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Perspective table from python clients, and to that end client libraries are
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implemented for both Tornado and AIOHTTP.
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## Example
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A simple example which loads an [Apache Arrow](https://arrow.apache.org/) and
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computes a "Group By" operation, returning a new Arrow.
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```python
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from perspective import Server
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client = Server().new_local_client()
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table = client.table(arrow_bytes_data)
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view = table.view(group_by = ["CounterParty", "Security"])
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arrow = view.to_arrow()
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```
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[More Examples](https://github.com/perspective-dev/perspective/tree/master/examples)
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are available on GitHub.
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## What's included
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The `perspective` module exports several tools:
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- `Server` the constructor for a new instance of the Perspective data engine.
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- The `perspective.widget` module exports `PerspectiveWidget`, the JupyterLab
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widget for interactive visualization in a notebook cell.
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- The `perspective.handlers` modules exports web frameworks handlers that
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interface with a `perspective-client` in JavaScript.
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- `perspective.handlers.tornado.PerspectiveTornadoHandler` for
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[Tornado](https://www.tornadoweb.org/)
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- `perspective.handlers.starlette.PerspectiveStarletteHandler` for
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[Starlette](https://www.starlette.io/) and
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[FastAPI](https://fastapi.tiangolo.com)
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- `perspective.handlers.aiohttp.PerspectiveAIOHTTPHandler` for
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[AIOHTTP](https://docs.aiohttp.org),
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### Virtual UI server
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As `<perspective-viewer>` or any other Perspective `Client` will only consume
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the data necessary to render the current screen (or whatever else was requested
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via the API), this runtime mode allows large datasets without the need to copy
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them entirely to the Browser, at the expense of network latency on UI
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interaction/API calls.
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### Jupyterlab
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`PerspectiveWidget` is a JupyterLab widget that implements the same API as
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`<perspective-viewer>`, allows running such a viewer in
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[JupyterLab](https://jupyterlab.readthedocs.io/en/stable/) in either server or
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client (via WebAssembly) mode. `PerspectiveWidget` is compatible with Jupyterlab
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3 and Jupyter Notebook 6 via a
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[prebuilt extension](https://jupyterlab.readthedocs.io/en/stable/extension/extension_dev.html#prebuilt-extensions).
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To use it, simply install `perspective-python` and the extensions should be
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available.
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`perspective-python`'s JupyterLab extension also provides convenient builtin
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viewers for `csv`, `json`, or `arrow` files. Simply right-click on a file with
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this extension and choose the appropriate `Perpective` option from the context
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menu.
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