using-python-in-mojo.md

🐍 using python in mojo: a to z

with v0.4.0

👷 under active development, see contributions

Import python in mojo

from python import Python

create mutable variable res

def main():
    var res:PythonObject 

list comprehension

    res = Python.evaluate("[x*x for x in range(1,4)]")

    for i in res: # i is a PythonObject
        let element:Float64 = i.to_float64()
        print(element) #1.0 4.0 9.0

call methods

    res = " and " #res is a PythonObject 

    #call join method
    res = res.join(["mojo","python"])

    print(res) #print: mojo and python

list

    res =[]
    res.append(Float64(1))
    res.append("hello world")
    res.append(True)
    res.pop()
    res.append(False)
    print(res) #[1.0, 'hello world', False]

tuples

    res = (True,0)
    print(res[0])
    print(res[1])

get and call python functions

    res = Python.evaluate("bin")
    print(res(15)) #0b1111

types

    res = 1.0
    print(res.__class__.__name__) #float

instance

    res = True
    let is_instance = Python.evaluate("isinstance")
    let float_type = Python.evaluate("bool")
    print(is_instance(res,float_type))

convert to mojo types

    res = "hello world"
    let res_b:String = res.upper().to_string()
    print(res_b) #HELLO WORLD

    res = 1.0
    let res_c:Float64 = res.to_float64()

    res = 123
    let res_d:Int = res.__index__()

    res = True
    let res_e:Bool = res.__bool__()

with pip modules

numpy linspace

    res = Python.import_module("numpy").linspace(0, 1.0, 5)
    print(res) #[0.   0.25 0.5  0.75 1.  ]

matplotlib plotting

    res = Python.import_module("matplotlib.pyplot")
    res.plot([1.1,2.2,4.4])
    res.show()

importing a custom python file

main.mojo:

from python import Python

def main():
    #path to the file (current directory)
    Python.add_to_path("./")

    #name of the file without .py
    let my_module = Python.import_module("python_file")

    my_module.my_func(2, 3)

python_file.py:

def my_func(a,b):
    print(a+b)