将python与knitr一起使用

Question

我想和knitr一起使用python.但是,python块似乎单独进行评估,并且变量定义在块之间丢失.

怎么解决这个？

最小的例子:

test.pymd

---
title: "Minimal example"
---

With a print statement.

```{r hello}
x = 'Hello, Python World!'
print(x)
```

Without a print statement.

```{r world}
print(x)
```

test.md

---
title: "Minimal example"
---

With a print statement.


```python
x = 'Hello, Python World!'
print(x)
```

```
Hello, Python World!
```

Without a print statement.


```python
print(x)
```

```
Traceback (most recent call last):
  File "<string>", line 1, in <module>
NameError: name 'x' is not defined
```

knit2py.r

#! /usr/bin/Rscript --vanilla

args <- commandArgs(TRUE)

if(length(args) < 1) {
    message("Need arguments in the format: %.pymd [%.md]")
    q(status=1)
}

name <- substr(args[1],1,nchar(args[1])-4)

if(length(args) < 2) {
    args[2] <- paste0(name,".md")
}

library(knitr)
opts_chunk$set(engine = 'python')

res <- try(knit(args[1], args[2]))

if(inherits(res, "try-error")) {
    message("Could not successfully knit RMD (or PYMD) to MD")
    q(status=1)
} else q()

现在运行:

./knit2py.r test.pymd test.md 

Answer 1

是的，的确是这样，的确，knitr当前无法评估除R以外的语言在多个块上扩展的代码。解决方案不是使用knitr，而是使用pweave。对源文件的修改很小：

测试文件

---
title: "Minimal example"
---

With a print statement.

<<>>=
x = 'Hello, Python World!'
print(x)
@

Without a print statement.

<<>>=
print(x)
@

The end.

现在运行：

pweave -f pandoc test.mdw

在pweave的网站上有一条注释，指出使用python3进行pip安装会失败。但是，仅运行时，我一点也没有问题：

pip install pweave
pip install markdown

也许，这只是一个旧的音符。