Org Babel can't execute script that takes table as input - emacs

Question

I want to learn Org Babel so I'm going through Code Blocks in Org.
I'm trying to execute the script in the basic tutorial and for some reason can't do it.
I'm supposed to feed a table as input to a function. This is the table:
#+name: tbl-example-data()
#+begin_src R
runif(n=5, min=0, max=1)
#+end_src
#+RESULTS: tbl-example-data
| 0.607781215803698 |
| 0.157157169422135 |
| 0.675619817571715 |
| 0.0488600700628012 |
| 0.998780139256269 |
The next function is the function to be executed:
#+name: R-mean(x)
#+begin_src R
mean(x)
#+end_src
When I try to run it by pressing C-c C-c I get
Variable "x" in block "R-mean" must be assigned a default value.
I tried to explicitly run the R-mean(x) function like so:
#+call: R-mean(tbl-example-data)
Unfortunately I get:
Reference 'R-mean' not found in this buffer.
How do I run the R-mean function using the values from tbl-example-data?
Thanks in advance.
Jenia
Okay I changed the code as per instructions:
#+NAME: tbl-example-data()
#+BEGIN_SRC R :results value <-------------------- changed
runif(n=5, min=0, max=1)
#+END_SRC
#+RESULTS: tbl-example-data
| 0.565871287835762 |
| 0.457158328965306 |
| 0.0498181856237352 |
| 0.988381117349491 |
| 0.898329895688221 |
#+NAME: R-mean(x)
#+BEGIN_SRC R :var x=tbl-example-data <-------------- changed
mean(x)
#+END_SRC
#+call: R-mean(x=tbl-example-data)
It returns me this:
Reference 'R-mean' not found in this buffer.
I dont know what I'm doing wrong.

Answer 1

You only need to make a couple of small changes in order to make this work.
Add :results value to the header of your first code block:
#+NAME: tbl-example-data()
#+BEGIN_SRC R :results value
runif(n=5, min=0, max=1)
#+END_SRC
#+RESULTS: tbl-example-data
...
Add :var x=tbl-example-data to the header of your second code block:
#+NAME: R-mean(x)
#+BEGIN_SRC R :var x=tbl-example-data
mean(x)
#+END_SRC
With these changes in place, both ways you describe for obtaining the final result will work. Evaluating the second code block via C-c C-c gives:
#+RESULTS: R-mean
: 0.49763968242332357
And calling the R-mean function via #+CALL: R-mean(tbl-example-data) produces:
#+RESULTS:
: 0.49763968242332357
Sources
Capturing the Results of Code Evaluation
Arguments to Code Blocks

Answer 2

I know this is a very old question, but I wanted to add this in case it will be useful for others. itsjeyd's answer didn't fully work for me either, and I believe this is why.
There are three changes that need to be made.
As itsjeyd pointed out, you need a default value for x in your function R-mean. You can put :var x=tbl-example-data, but you could also just put :var x=0.
You need to remove change #+NAME: R-mean(x) to #+NAME: R-mean.
When you pass x it's being read as a one-column data frame, not a vector (for me at least). So you may need to change mean(x) to mean(x[, 1]).
For me, the first code block returns a table regardless of whether I use :results value. Your mileage may vary.
This works for me.
#+NAME: tbl-example-data()
#+BEGIN_SRC R
runif(n=5, min=0, max=1)
#+END_SRC
#+RESULTS: tbl-example-data
| 0.926858797203749 |
| 0.830021075671539 |
| 0.788423302117735 |
| 0.794694420881569 |
| 0.943031084956601 |
#+NAME: R-mean
#+BEGIN_SRC R :var x=""
mean(x[, 1])
#+END_SRC
#+call: R-mean(x=tbl-example-data)
#+RESULTS:
: 0.856605736166239
One final note. If you have parentheses at the end of your first block name, #+NAME: tbl-example-data(), this block appears not to be evaluate anew each time. So running the call statement multiple times produces the same result.
But if you remove the parentheses, giving #+NAME: tbl-example-data, the block is evaluate each time the call statement is run, producing a different result each time. I didn't know this.
Hope that helps!