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rreticulate

Why is reticulate::py_available() FALSE until I I run reticulate::py_run_string("")?

Why do I first have to submit something through reticulate::py_run_string() for reticulate::py_available() to return TRUE?

I ran the below set of calls through a clean R session:

> packageVersion("reticulate")
[1] ‘1.40.0’
> reticulate::py_available()
[1] FALSE
> Sys.setenv(RETICULATE_PYTHON = "/usr/bin/python3")
> reticulate::py_available()
[1] FALSE
> reticulate::py_run_string("")
> reticulate::py_available()
[1] TRUE
Solution

  • py_run_string("") triggers Python initialization while py_available() by default does not, it only checks if Python is already initialized in current R session. Though you can set initialize to change that behaviour.

    Or perhaps it's reticulate::py_discover_config() you are after -- it does not load Python, just attempts to figure out config:

    # discover config without initializing python
reticulate::py_discover_config()$python
#> [1] "C:/Users/margusl/miniforge3/envs/py312/python.exe"
reticulate::py_available()
#> [1] FALSE

# force init before checking:
reticulate::py_available(initialize = TRUE)
#> [1] TRUE
reticulate::py_available()
#> [1] TRUE