pyodide/docs/api_reference.md

API Reference

pyodide version 0.1.0

Backward compatibility of the API is not guaranteed at this point.

Python API

pyodide.open_url(url)

Fetches a given url and returns a io.StringIO to access its contents.

Parameters

name	type	description
url	str	the URL to open

Returns

A io.StringIO object with the URL contents./

pyodide.eval_code(code, ns)

Runs a string of code. The last part of the string may be an expression, in which case, its value is returned.

This function may be overridden to change how pyodide.runPython interprets code, for example to perform some preprocessing on the Python code first.

Parameters

name	type	description
code	str	the code to evaluate
ns	dict	evaluation name space

Returns

Either the resulting object or None.

pyodide.as_nested_list(obj)

Converts Javascript nested arrays to Python nested lists. This conversion can not be performed automatically, because Javascript Arrays and Objects can be combined in ways that are ambiguous.

Parameters

name	type	description
obj	JS Object	The object to convert

Returns

The object as nested Python lists.

Javascript API

pyodide.loadPackage(names)

Load a package or a list of packages over the network.

This makes the files for the package available in the virtual filesystem. The package needs to be imported from Python before it can be used.

Parameters

name	type	description
names	{String, Array}	package name, or URL. Can be either a single element, or an array.
messageCallback	function	A callback, called with progress messages. (optional)

Returns

Loading is asynchronous, therefore, this returns a Promise.

pyodide.loadedPackages

Array with loaded packages.

Use Object.keys(pyodide.loadedPackages) to access the names of the loaded packages, and pyodide.loadedPackages[package_name] to access install location for a particular package_name.

pyodide.pyimport(name)

Access a Python object from Javascript. The object must be in the global Python namespace.

For example, to access the foo Python object from Javascript:

var foo = pyodide.pyimport('foo')

Parameters

name	type	description
names	String	Python variable name

Returns

name	type	description
object	any	If one of the basic types (string,
		number, boolean, array, object), the
		Python object is converted to
		Javascript and returned. For other
		types, a Proxy object to the Python
		object is returned.

pyodide.globals

An object whose attributes are members of the Python global namespace. This is a more convenient alternative to pyodide.pyimport.

For example, to access the foo Python object from Javascript:

pyodide.globals.foo

pyodide.repr(obj)

Gets the Python's string representation of an object.

This is equivalent to calling repr(obj) in Python.

Parameters

name	type	description
obj	any	Input object

Returns

name	type	description
str_repr	String	String representation of the input object

pyodide.runPython(code)

Runs a string of code. The last part of the string may be an expression, in which case, its value is returned.

Parameters

name	type	description
code	String	Python code to evaluate

Returns

name	type	description
jsresult	any	Result, converted to Javascript

pyodide.runPythonAsync(code, messageCallback)

Runs Python code, possibly asynchronously loading any known packages that the code chunk imports.

For example, given the following code chunk

import numpy as np
x = np.array([1, 2, 3])

pyodide will first call pyodide.loadPackage(['numpy']), and then run the code chunk, returning the result. Since package fetching must happen asynchronously, this function returns a Promise which resolves to the output. For example, to use:

pyodide.runPythonAsync(code, messageCallback)
  .then((output) => handleOutput(output))

Parameters

name	type	description
code	String	Python code to evaluate
messageCallback	function	Callback given status messages
		(optional)

Returns

name	type	description
result	Promise	Resolves to the result of the code chunk

pyodide.version()

Returns the pyodide version.

It can be either the exact release version (e.g. 0.1.0), or the latest release version followed by the number of commits since, and the git hash of the current commit (e.g. 0.1.0-1-bd84646).

Parameters

None

Returns

name	type	description
version	String	Pyodide version string