Using reticulate's Python Engine with knitr

# load reticulate and set up engine
knitr::knit_engines$set(python = eng_python)

# use specific environment if available
python <- "~/.virtualenvs/python-3.7.7-venv/bin/python"
if (file.exists(python))
  reticulate::use_python(python, required = TRUE)

# use rlang error handler
if (requireNamespace("rlang", quietly = TRUE))
  options(error = rlang::entrace)

Python variables live across chunk boundaries.

x = 1
y = 2

Plots generated by matplotlib are properly displayed.

```{python, fig.width=4, fig.height=3, dev="svg"} import matplotlib.pyplot as plt

plt.plot([1, 2, 3, 4])

plt.plot([1, 2, 3, 4])

Python can access objects available in the R environment.

x <- 1:5
y <- 6:10

r.hello = "World"
r['answer'] = 42

Arbitrary R code can be evaluated from Python.

mpg = r["mtcars$mpg[1:5]"]
y = "a,b,c".split(",")

```{python echo=FALSE} print ("Chunk with echo = FALSE")

- #130: The `results` chunk option is respected for Python outputs. Source, but not output, should show in the following output.

```{python results='hide'}
print ("Chunk with results = 'hide'")

```{python include=FALSE} print ("Chunk with include = FALSE")

- #130: The `eval` chunk option is respected for Python outputs.

```{python eval=FALSE}
# We have set 'eval = FALSE' here
r["abc"] = 1
exists("abc", envir = globalenv())

Respect the error=TRUE chunk option -- allow execution even after a Python error occurs.

```{python, error=TRUE} raise RuntimeError("oops!") print("This line is still reached.")

Ensure that lines with multiple statements are only run once.

print("abc"); print("123")

Ensure that syntax errors do not block document generation when eval = FALSE.

```{python, eval=FALSE} here be syntax errors

Output from bare statements should also be printed.

"Hello, world!"
[x for x in range(10)]

Expressions that generate plots should be shown, if that is the final statement within a chunk.

import numpy as np, pandas as pd
a = np.random.normal(size=1000)

Ensure that outputs with results = "hold" are held to the end.

```{python, results="hold"} print(1) print(2) print(3)

plotly plots should be auto-printed and displayed.

import as px
fig = px.scatter(x=[1, 2, 3], y=[5, 4, 6])

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reticulate documentation built on May 3, 2021, 9:07 a.m.