Differences and upgrade considerations from embedPy
As outlined here PyKX provides users with the ability to execute Python code within a q session similar to embedPy. This document outlines points of consideration when upgrading from embedPy to PyKX under q both with respect to the function mappings between the two interfaces and differences in their behaviour.
Functional differences
q symbol and string support
EmbedPy does not allow users to discern between q string and symbol types when converting to Python. In both cases these are converted to str objects in Python. As a result round trip conversions are not supported in embedPy for symbols, PyKX does support such round trip operations:
q).p.set[`a;"test"]
q)"test"~.p.get[`a]`
1b
q).p.set[`b;`test]
q)`test~.p.get[`b]`
0bq).pykx.set[`a;"test"]
q)"test"~.pykx.get[`a]`
1b
q).pykx.set[`b;`test]
q)`test~.pykx.get[`b]`
1bPython object type support
EmbedPy contains a fundamental limitation with respect to the data formats that are supported when converting betwen q and Python. Namely that all q objects when passed to Python functions use the analagous Python/Numpy representation. This limitation means that a user of embedPy must handle their own data conversions when handling Pandas or PyArrow objects.
PyKX natively supports data conversions from q to Python, Numpy, Pandas and PyArrow and as such can support workflows which previously required users to manually control these conversions, for example:
q).pykx.print .pykx.eval["lambda x:type(x)"] .pykx.topd ([]10?1f)
Functionality mapping
The following table describes the function mapping from PyKX to embedPy for various elements of the supported functionality within embedPy, where a mapping supported this will be explicitly noted. Where workarounds exist these are additionally noted.
| Description | PyKX | embedPy |
|---|---|---|
| Library loading | \l pykx.q |
\l p.q |
| Importing Python Libraries as wrapped Python objects | .pykx.import |
.p.import |
| Setting objects in Python Memory | .pykx.set |
.p.set |
| Retrieving Python objects from Memory | .pykx.get |
.p.get |
| Converting Python objects to q | .pykx.toq |
.p.py2q |
| Execute Python code returning as intermediary q/Python object | .pykx.eval |
.p.eval |
| Execute Python code returning a q object | .pykx.qeval |
.p.qeval |
| Execute Python code returning a Python foreign object | .pykx.pyeval |
.p.eval |
| Retrieve a printable representation of a supplied PyKX/q objext | .pykx.repr |
.p.repr |
| Set an attribute on a supplied Python object | .pykx.setattr |
.p.setattr |
| Retrieve an attribute from a supplied Python object | .pykx.getattr |
.p.getattr |
| Convert a Python foreign object to a wrapped object for conversion | .pykx.wrap |
.p.wrap |
| Convert a wrapped Python object to a Python foreign object | .pykx.unwrap |
.p.unwrap |
| Print a Python object to standard out | .pykx.print |
.p.print |
| Import a Python library as a Python foreign object | .pykx.pyimport |
.p.pyimport |
| Generate a callable Python function returning a Python foreign object | .pykx.pycallable |
.p.pycallable |
| Generate a callable Python function returning a q result | .pykx.qcallable |
.p.qcallable |
| Interactive Python help string | Unsupported | .p.help |
| Retrieval of Python help string as a q string | Unsupported | .p.helpstr |
| Convert a q object to a Python foreign object | Unsupported | .p.q2py |
| Create a Python closure using a q function | Unsupported | .p.closure |
| Create a Python generator using a q function | Unsupported | .p.generator |