Stata Python

Stata supports calling out to an embedded Python interpretter.

Installation

Most system configuration is done with the python set command.

Stata can list recognized Python environments with python search. To add an unrecognized environment, try:

python set exec "C:\path\to\python\installation"

To prepend or append to the PYTHONPATH, use:

python set userpath "C:\foo" "C:\bar" "C:\baz", [prepend]

To make these settings permanent, add the permanent option.

Usage

REPL

A Python REPL is entered with the python command alone. It prints to the screen a reminder that the end command is used to exit the environment.

Stata local variables are accessed with quotations.

. local int_var = 3
. local str_var = "This is a Stata string"
. python
---------------------------------------- python (type end to exit) -----------
>>> `int_var'
3
>>> "`str_var'".split(" ")
['This', 'is', 'a', 'Stata', 'string']

Within the REPL, prefix a Stata command with stata:.

>>> stata: sysuse auto, clear

SFI

A foreign function interface module is also available.

from sfi import Data
pymake = Data.get('make')
# do something

This can be used within a REPL as shown above.

Scope

A Python scope can be entered with python:. This Python environment lasts only until the end of the statement.

To submit multiple statements on a scope, delimit them with semicolons.

Do Files

While an interactive python: scope lasts only until the end of the statement, a do file python: scope continues until explicitly terminated by the end command.

sysuse auto, clear
python:
from sfi import Data
pymake = Data.get(’make’)
# do something
end

A common design pattern is to define Python functions within an ado file with the primary Stata function being a thin interface for them.

program varsum
    version 16.0
    syntax varname [if] [in]

    python: _varsum("`varlist'", "`touse'")
    display as txt " sum of ‘varlist’: " as res r(sum)
end

python:
from sfi import Data, Scalar
def _varsum(varname, touse):
    x = Data.get(varname, None, touse)
    Scalar.setValue("r(sum)", sum(x))
end

. sysuse auto, clear
(1978 Automobile Data)

. varsum price
sum of price: 456229

. varsum price if foreign
sum of price: 140463

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