I sourced my function nnn.R using the line :
source("nnn.R")*
and did not get any errors, but when I try to run it, this is what I get:
Error: could not find function "nnn"*
this all what the function has inside
function (x) is.null(x)
nnn.R is a file, not a function. The file must contain a function, defined as:
nnn <- function(x) {
return (is.null(x))
}
Note that nnn.R may contain several function definitions. See for instance this tutorial.
Related
I am trying to create a function to clean data and return as a data.frame in R.
I'm using the map_df() function to return the cleaned data as a data.frame, and have a function written to clean the data.
The first thing I do is pull a list of files from a folder, then iterate through them and clean each file. I have a pre-defined set specifying which column names to pull (stored in selectCols) in case of variation between files:
files <- list.files(filepath,full.names=F)
colInd <- which(names(fread(files[i],nrows=0)) %in% gsub("_","",selectCols))
I also have a function to clean my data, which uses fread() to read in the .csv files. It takes colInd and i as arguments to clean files iteratively.
cleanData <- function(files,i,colInd) {
addData <- fread(files[i],select=c(colInd))
[...]
}
Overall it looks like this (as a recursive function):
i <- 1
files <- list.files(filepath,full.names=F)
iterateCleaning <- function(files,i) {
colInd <- (which(names(fread(files[i],nrows=0)) %in% gsubs("_","",selectCols))
if (length(colInd)==length(selectCols)) {
newData <- map_df(files,cleanData)
saveToFolder(newData,i,files)
}
else {}
i=i+1
if (i<-length(files)){
iterateCleaning(files,i)
}
else {}
}
When I try to run without specifying the arguments for my function I get this error:
Error in fread(files,select=c(colInd)):
argument "colInd" is missing, with no default.
When I insert it into my map_df() I do it like so:
newData <- map_df(files,i,colInd,cleanData)
Then I get this error:
Error in as_mapper(.f,...): object 'colInd' not found.
Any suggestions for resolving this error? As I understand it, map_df() applies to each element in the function, but I don't need it applied to the i and colInd inputs, I just need them for the function I am calling in map_df(). How can I call map_df() on a function that requires additional arguments?
I read the documentation but it seemed a bit confusing. It says for a single-argument function to use "." and for two-argument functions to use .x and .y, but I'm not sure what it means. My initial guess is something like these, but neither line works):
newData <- map_df(files,cleanData,.i,.colInd)
newData <- map_df(files,cleanData,.x=i,.y=colInd)
Any recommendations? Will I have the same output if I just call map_df() afterwards on the output of my function?
There is my function code
fun(arg1){
if(arg1 == 'ggwp'){
new.fun1()
}
}
>fun(ggwp)
>Error in fun(ggwp): object 'ggwp' not found.
i don't know how to use if condition that make arg1 = str, then run a new function in R. It is different from C. There is error when I try this code. So, how do I make it work?
I have two .R files, plotDataSet(..) and plotAllDataSets(). plotDataSet(..) makes a call to curve(..) (in the R graphics library), while plotAllDataSets() makes a call to plotDataSet(..). plotDataSet(..) takes a function as a parameter, and passes it to curve(..).
I want to pass in my function argument for curve(..) into plotDataSet(..) from a list of functions, such as:
v <- c(function(x){x}, function(x){x*x}, function(x){x*x}, function(x){x*x*x},
function(x){x*x}, function(x){x*x*x}, function(x){x*x*x})
for (i in 1:7) {
plotSaveData(data, v[i], i)
}
I get the following output: Error in eval(expr, envir, enclos) :
could not find function "expectedOrderEquation".
Interestingly, when I call plotDataSet(..) and pass in a function like function(x){x*x}, it works fine:
for (i in 1:7) {
plotSaveData(data, function(x) {x}, i)
}
But this won't let me call plotSaveData(..) while cycling through a list of functions.
Can someone please explain why this does not work?
I hope this is sufficient, but I am happy to provide more context as needed. Also, I am a bit new to R, so any corrections to my descriptions would be helpful.
use double brackets instead of single brackets
v[[i]] instead of v[i]
Have a look at the difference between these two:
v[[i]] (3)
v[i] (3) # error
The single brackets returns a list, whose contents is a function
The double brackets returns the function.
In my R development I need to wrap function primitives in proto objects so that a number of arguments can be automatically passed to the functions when the $perform() method of the object is invoked. The function invocation internally happens via do.call(). All is well, except when the function attempts to access variables from the closure within which it is defined. In that case, the function cannot resolve the names.
Here is the smallest example I have found that reproduces the behavior:
library(proto)
make_command <- function(operation) {
proto(
func = operation,
perform = function(., ...) {
func <- with(., func) # unbinds proto method
do.call(func, list(), envir=environment(operation))
}
)
}
test_case <- function() {
result <- 100
make_command(function() result)$perform()
}
# Will generate error:
# Error in function () : object 'result' not found
test_case()
I have a reproducible testthat test that also outputs a lot of diagnostic output. The diagnostic output has me stumped. By looking up the parent environment chain, my diagnostic code, which lives inside the function, finds and prints the very same variable the function fails to find. See this gist..
How can the environment for do.call be set up correctly?
This was the final answer after an offline discussion with the poster:
make_command <- function(operation) {
proto(perform = function(.) operation())
}
I think the issue here is clearer and easier to explore if you:
Replace the anonymous function within make_command() with a named one.
Make that function open a browser() (instead of trying to get result). That way you can look around to see where you are and what's going on.
Try this, which should clarify the cause of your problem:
test_case <- function() {
result <- 100
myFun <- function() browser()
make_command(myFun)$perform()
}
test_case()
## Then from within the browser:
#
parent.env(environment())
# <environment: 0x0d8de854>
# attr(,"class")
# [1] "proto" "environment"
get("result", parent.env(environment()))
# Error in get("result", parent.env(environment())) :
# object 'result' not found
#
parent.frame()
# <environment: 0x0d8ddfc0>
get("result", parent.frame()) ## (This works, so points towards a solution.)
# [1] 100
Here's the problem. Although you think you're evaluating myFun(), whose environment is the evaluation frame of test_case(), your call to do.call(func, ...) is really evaluating func(), whose environment is the proto environment within which it was defined. After looking for and not finding result in its own frame, the call to func() follows the rules of lexical scoping, and next looks in the proto environment. Neither it nor its parent environment contains an object named result, resulting in the error message you received.
If this doesn't immediately make sense, you can keep poking around within the browser. Here are a few further calls you might find helpful:
environment(get("myFun", parent.frame()))
ls(environment(get("myFun", parent.frame())))
environment(get("func", parent.env(environment())))
ls(environment(get("func", parent.env(environment()))))
I have a wrapper around the in-built warning() function in R that basically calls warning(sprintf(...)):
warningf <- function(...)
warning(sprintf(...))
This is because I use warning(sprintf(...)) so often that I decided to make a function out of it (it's in a package I have of functions I use often).
I then use warningf when I write functions. i.e., instead of writing:
f <- function() {
# ... do stuff
warning(sprintf('I have %i bananas!',2))
# ... do stuff
}
I write:
f <- function() {
# ... do stuff
warningf('I have %i bananas!',2)
# ... do stuff
}
If I call the first f(), I get:
Warning message:
In f() : I have 2 bananas!
This is good - it tells me where the warning came from f() and what went wrong.
If I call the second f(), I get:
Warning message:
In warningf("I have %i bananas!",2) : I have 2 bananas!
This is not ideal - it tells me the warning was in the warningf function (of course, because it's the warningf function that calls warning, not f), masking the fact that it actually came from the f() function.
So my question is : Can I somehow "raise" the warning call so it displays the warning in f() message instead of the warning in warningf ?
One way of dealing with this is to get a list of the environments in your calling stack, and then pasting the name of the parent frame in your warning.
You do this with the function sys.call() which returns an item in the call stack. You want to extract the second from last element in this list, i.e. the parent to warningf:
warningf <- function(...){
parent.call <- sys.call(sys.nframe() - 1L)
warning(paste("In", deparse(parent.call), ":", sprintf(...)), call.=FALSE)
}
Now, if I run your function:
> f()
Warning message:
In f() : I have 2 bananas!
Later edit : deparse(parent.call) converts the call to a string in the case that the f() function had arguments, and shows the call as it was specified (ie including arguments etc).
I know it's old but, sys.call(sys.nframe() - 1L), or sys.call(-1),
returns a vector, with the function name and the argument.
If you use it inside paste() it will raise two warnings, one from the function and one from the argument.
The answer doesn't show because f() has no arguments.
sys.call(sys.nframe() - 1L)[1] does the trick.