Addons/api/python3

Overview

This addon has functions for calling J from Python.

Setup

Assuming J is already installed, use below commands to create a Python virtual environment for your project and install package.

Windows

python3 -m venv MyProject
cd MyProject
Set-ExecutionPolicy -Scope Process -ExecutionPolicy Bypass
.\Scripts\activate
pip install -e C:\your\path\to\j9.7\addons\api\python3

Linux/macOS

python3 -m venv MyProject
cd MyProject
source bin/activate
pip install -e /your/path/to/j9.7/addons/api/python3

Important for macOS users: The default system Python at /usr/bin/python3 is not suitable for most projects that use dynamic libraries, including this one. To avoid issues, use a user-managed Python installation (e.g. Homebrew, Python.org, Conda).

Initialization

Import

from jclient import JClient

and use with context manager

with JClient('/your/path/to/directory/j9.7') as jc:

or by standard object creation.

jc = JClient('/your/path/to/directory/j9.7')

Add load_profile=False after the path if you need a totally clean J session.

Methods

get

Gets the value of J noun and returns it in Python format. J types are converted according to the below table.

J	Python
`literal`	`numpy.dtype('S1')`
`boolean`	`numpy.bool`
`integer`	`numpy.int64`
`floating`	`numpy.float64`
`complex`	`numpy.complex128`

val = jc.get('a')

set

Sets J noun with value from Python. Python types are converted according to the below table.

Python	J
`str`	`literal`
`bytes`	`literal`
`numpy.dtype('S1')`	`literal`
`numpy.bool`	`boolean`
`numpy.int64`	`integer`
`numpy.float64`	`floating`
`numpy.complex128`	`complex`

jc.set('a', numpy.array([7, 42, 10], dtype='int64'))

do

Executes given J sentence and returns error code (0 if no error).

err = jc.do('a =: 2 + 3')

script

Runs J script from the file at the given path and returns error code.

err = jc.script('/your/path/to/file.ijs')

getr

Returns the result string of the most recent J sentence.

res = jc.getr()

dor

Executes given J sentence and returns the result string.

res = jc.dor('2 + 3')

close

Closes J session.

jc.close()

repl

Runs simple J Read-Eval-Print Loop. Enter .... to exit the loop.

jc.repl()

See the jclient.py and test_jclient.py files in the addon for more details and examples.