R markdown: Accessing variable from code chunk (va

问题:

This question already has an answer here:

• Is there an R Markdown equivalent to \Sexpr{} in Sweave? 2 answers

In R markdown (knitr package), can I access a variable within the body of the document that was calculated in a code chunk?

回答1:

Yes. You can simply call any previously evaluated variable inline.

e.g. If you had previously created a data.frame in a chunk with df <- data.frame(x=1:10)

`r max(df$x)`

Should produce

10

回答2:

I would like to add that this is not the case for other languages than R. I know the question is solved and about R, but maybe someone else finds this useful:

Except engine='R' (default), all chunks are executed in separate sessions, so the variables cannot be directly shared. If we want to make use of objects created in previous chunks, we usually have to write them to files (as side effects). For the bash engine, we can use Sys.setenv() to export variables from R to bash (example). Another approach is to use the (experimental) runr package.

Source

Example in R:

x = 4

print(x)

## [1] 4

Python Example 2a):

x=1
print(x)

## 1

Python Example 2b):

print(x)

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

Just FYI.

回答3:

You can acces to variable previously created so

`r variable`

But if the variable is numeric and you want add to a pdf document, you should convert variable in string so

`r toString(variable)`