I would like to make R a little bit easier to execute system command. Something like ipython vs python. Here are some thoughts:
Define cd function to change working directory by wrapping up the getwd and setwd
Define an operator to wrap up the system() command so that I can run something like "$ls" to replace the system("ls")
The first one is easy to accomplish. However, I am stuck with the second one. I found no ways to redefine an operator in R for a string. Then I took a step back, I tried to define a sys(param). But now, I still need to input the quotation marks. e.g. I need to run sys("ls") instead of sys(ls) to list the directory. Is there a way to make the parameter assume it is a string even without the quotation marks? Thanks. Any suggestions are welcome.
Updated to simplify functions (remove a regexp) and add support for character input
You can use match.call inside a function so that you can call the function without using quotation marks like this.
sys <- function(...) {
command <- match.call()[[2L]]
if (!is.character(command)) {
command <- gsub("- ", "-", deparse(command))
}
system(command)
}
Now, either of the following are equivalent to system("ls -a")
sys("ls -a")
sys(ls -a)
The sys function above extracts the second component of the call which is the stuff between the parentheses. i.e. ls -a or "ls -a" in these examples. It then passes that to system (through deparse first if it is not character)
[I added support for strings because otherwise it doesn't work with forward slashes, dots, etc. For example, sys(ls /home) does not work, but sys("ls /home") does.]
However, this still requires using parentheses :-(
To avoid the use of parentheses, you can mask an operator. In the initial version of this answer, I showed how to mask ! which is not a good a idea. You suggested using ? in the comments which could be done like this.
`?` <- function(...) {
command <- match.call()[[2L]]
if (!is.character(command)) {
command <- gsub("- ", "-", deparse(command))
}
system(command)
}
Now, this is the same as system("ls -a -l")
?ls -a -l
But, if you need to use forward slashes, you'd have to use quotes like this
?"ls /home"
Alternatively, you could create a special binary operator
"%sys%" <- function(...) {
system(sub("%sys%", "", deparse(match.call())))
}
You can use it like this
ls %sys% -l
ls %sys% .
If you need to use forward slashes, you have to quote the right side
ls %sys% "/home"
A downside is that it requires exactly one argument on the right side of the operator.
Related
I run R on Windows, and have a csv file on the Desktop. I load it as follows,
x<-read.csv("C:\Users\surfcat\Desktop\2006_dissimilarity.csv",header=TRUE)
but the R gives the following error message
Error: '\U' used without hex digits in character string starting "C:\U"
So what's the correct way to load this file. I am using Vista
replace all the \ with \\.
it's trying to escape the next character in this case the U so to insert a \ you need to insert an escaped \ which is \\
Please do not mark this response as correct as smitec has already answered correctly. I'm including a convenience function I keep in my .First library that makes converting a windows path to the format that works in R (the methods described by Sacha Epskamp). Simply copy the path to your clipboard (ctrl + c) and then run the function as pathPrep(). No need for an argument. The path is printed to your console correctly and written to your clipboard for easy pasting to a script. Hope this is helpful.
pathPrep <- function(path = "clipboard") {
y <- if (path == "clipboard") {
readClipboard()
} else {
cat("Please enter the path:\n\n")
readline()
}
x <- chartr("\\", "/", y)
writeClipboard(x)
return(x)
}
Solution
Try this: x <- read.csv("C:/Users/surfcat/Desktop/2006_dissimilarity.csv", header=TRUE)
Explanation
R is not able to understand normal windows paths correctly because the "\" has special meaning - it is used as escape character to give following characters special meaning (\n for newline, \t for tab, \r for carriage return, ..., have a look here ).
Because R does not know the sequence \U it complains. Just replace the "\" with "/" or use an additional "\" to escape the "\" from its special meaning and everything works smooth.
Alternative
On windows, I think the best thing to do to improve your workflow with windows specific paths in R is to use e.g. AutoHotkey which allows for custom hotkeys:
define a Hotkey, e.g. Cntr-Shift-V
assigns it an procedure that replaces backslashes within your Clipboard with
slaches ...
when ever you want to copy paste a path into R you can use Cntr-Shift-V instead of Cntr-V
Et-voila
AutoHotkey Code Snippet (link to homepage)
^+v::
StringReplace, clipboard, clipboard, \, /, All
SendInput, %clipboard%
My Solution is to define an RStudio snippet as follows:
snippet pp
"`r gsub("\\\\", "\\\\\\\\\\\\\\\\", readClipboard())`"
This snippet converts backslashes \ into double backslashes \\. The following version will work if you prefer to convert backslahes to forward slashes /.
snippet pp
"`r gsub("\\\\", "/", readClipboard())`"
Once your preferred snippet is defined, paste a path from the clipboard by typing p-p-TAB-ENTER (that is pp and then the tab key and then enter) and the path will be magically inserted with R friendly delimiters.
Replace back slashes \ with forward slashes / when running windows machine
I know this is really old, but if you are copying and pasting anyway, you can just use:
read.csv(readClipboard())
readClipboard() escapes the back-slashes for you. Just remember to make sure the ".csv" is included in your copy, perhaps with this:
read.csv(paste0(readClipboard(),'.csv'))
And if you really want to minimize your typing you can use some functions:
setWD <- function(){
setwd(readClipboard())
}
readCSV <- function(){
return(readr::read_csv(paste0(readClipboard(),'.csv')))
}
#copy directory path
setWD()
#copy file name
df <- readCSV()
Replacing backslash with forward slash worked for me on Windows.
The best way to deal with this in case of txt file which contains data for text mining (speech, newsletter, etc.) is to replace "\" with "/".
Example:
file<-Corpus(DirSource("C:/Users/PRATEEK/Desktop/training tool/Text Analytics/text_file_main"))
I think that R is reading the '\' in the string as an escape character. For example \n creates a new line within a string, \t creates a new tab within the string.
'\' will work because R will recognize this as a normal backslash.
readClipboard() works directly too. Copy the path into your clipboard
C:\Users\surfcat\Desktop\2006_dissimilarity.csv
Then
readClipboard()
appears as
[1] "C:\\Users\\surfcat\\Desktop\\2006_dissimilarity.csv"
A simple way is to use python.
in python terminal type
r"C:\Users\surfcat\Desktop\2006_dissimilarity.csv"
and you'll get back
'C:\Users\surfcat\Desktop\2006_dissimilarity.csv'
I run R on Windows, and have a csv file on the Desktop. I load it as follows,
x<-read.csv("C:\Users\surfcat\Desktop\2006_dissimilarity.csv",header=TRUE)
but the R gives the following error message
Error: '\U' used without hex digits in character string starting "C:\U"
So what's the correct way to load this file. I am using Vista
replace all the \ with \\.
it's trying to escape the next character in this case the U so to insert a \ you need to insert an escaped \ which is \\
Please do not mark this response as correct as smitec has already answered correctly. I'm including a convenience function I keep in my .First library that makes converting a windows path to the format that works in R (the methods described by Sacha Epskamp). Simply copy the path to your clipboard (ctrl + c) and then run the function as pathPrep(). No need for an argument. The path is printed to your console correctly and written to your clipboard for easy pasting to a script. Hope this is helpful.
pathPrep <- function(path = "clipboard") {
y <- if (path == "clipboard") {
readClipboard()
} else {
cat("Please enter the path:\n\n")
readline()
}
x <- chartr("\\", "/", y)
writeClipboard(x)
return(x)
}
Solution
Try this: x <- read.csv("C:/Users/surfcat/Desktop/2006_dissimilarity.csv", header=TRUE)
Explanation
R is not able to understand normal windows paths correctly because the "\" has special meaning - it is used as escape character to give following characters special meaning (\n for newline, \t for tab, \r for carriage return, ..., have a look here ).
Because R does not know the sequence \U it complains. Just replace the "\" with "/" or use an additional "\" to escape the "\" from its special meaning and everything works smooth.
Alternative
On windows, I think the best thing to do to improve your workflow with windows specific paths in R is to use e.g. AutoHotkey which allows for custom hotkeys:
define a Hotkey, e.g. Cntr-Shift-V
assigns it an procedure that replaces backslashes within your Clipboard with
slaches ...
when ever you want to copy paste a path into R you can use Cntr-Shift-V instead of Cntr-V
Et-voila
AutoHotkey Code Snippet (link to homepage)
^+v::
StringReplace, clipboard, clipboard, \, /, All
SendInput, %clipboard%
My Solution is to define an RStudio snippet as follows:
snippet pp
"`r gsub("\\\\", "\\\\\\\\\\\\\\\\", readClipboard())`"
This snippet converts backslashes \ into double backslashes \\. The following version will work if you prefer to convert backslahes to forward slashes /.
snippet pp
"`r gsub("\\\\", "/", readClipboard())`"
Once your preferred snippet is defined, paste a path from the clipboard by typing p-p-TAB-ENTER (that is pp and then the tab key and then enter) and the path will be magically inserted with R friendly delimiters.
Replace back slashes \ with forward slashes / when running windows machine
I know this is really old, but if you are copying and pasting anyway, you can just use:
read.csv(readClipboard())
readClipboard() escapes the back-slashes for you. Just remember to make sure the ".csv" is included in your copy, perhaps with this:
read.csv(paste0(readClipboard(),'.csv'))
And if you really want to minimize your typing you can use some functions:
setWD <- function(){
setwd(readClipboard())
}
readCSV <- function(){
return(readr::read_csv(paste0(readClipboard(),'.csv')))
}
#copy directory path
setWD()
#copy file name
df <- readCSV()
Replacing backslash with forward slash worked for me on Windows.
The best way to deal with this in case of txt file which contains data for text mining (speech, newsletter, etc.) is to replace "\" with "/".
Example:
file<-Corpus(DirSource("C:/Users/PRATEEK/Desktop/training tool/Text Analytics/text_file_main"))
I think that R is reading the '\' in the string as an escape character. For example \n creates a new line within a string, \t creates a new tab within the string.
'\' will work because R will recognize this as a normal backslash.
readClipboard() works directly too. Copy the path into your clipboard
C:\Users\surfcat\Desktop\2006_dissimilarity.csv
Then
readClipboard()
appears as
[1] "C:\\Users\\surfcat\\Desktop\\2006_dissimilarity.csv"
A simple way is to use python.
in python terminal type
r"C:\Users\surfcat\Desktop\2006_dissimilarity.csv"
and you'll get back
'C:\Users\surfcat\Desktop\2006_dissimilarity.csv'
I am using some simple bash commands inside of an R for-loop to create some files with unique names.
Since the command arguments change with each iteration, I thought of using eval(parse(text=paste(system2(...)))), something like this:
index <- 1:5
for (i in index){
eval(parse(text=paste('system2("echo","`some text`>> myfile_',i,'.txt")',sep = "")))
}
However, to define the text string that is the argument to echo, I need a third delimiter because single, double and back quotes don't work. The above code with back quotes produces five lines of:
sh: some: command not found
while using the other quotes produces other errors.
Are there other delimiters that will work in this case?
(Note: This is a successor question to my posting zsh: Command substitution and proper quoting , but now with an additional complication).
I have a function _iwpath_helper, which outputs to stdout a path, which possibly contains spaces. For the sake of this discussion, let's assume that _iwpath_helper always returns a constant text, for instance
function _iwpath_helper
{
echo "home/rovf/my directory with spaces"
}
I also have a function quote_stripped expects one parameter and if this parameter is surrounded by quotes, it removes them and returns the remaining text. If the parameter is not surrounded by quotes, it returns it unchanged. Here is its definition:
function quote_stripped
{
echo ${1//[\"\']/}
}
Now I combine both functions in the following way:
target=$(quote_stripped "${(q)$(_iwpath_helper)}")
(Of course, 'quote_stripped' would be unnecessary in this toy example, because _iwpath_helper doesn't return a quote-delimited path here, but in the real application, it sometimes does).
The problem now is that the variable target contains a real backslash character, i.e. if I do a
echo +++$target+++
I see
+++home/rovf/my\ directory\ with\ spaces
and if I try to
cd $target
I get on my system the error message, that the directory
home/rovf/my/ directory/ with/ spaces
would not exist.
(In case you are wondering where the forward slashes come from: I'm running on Cygwin, and I guess that the cd command just interprets backslashes as forward slashes in this case, to accomodate better for the Windows environment).
I guess the backslashes, which physically appear in the variable target are caused by the (q) expansion flag which I apply to $(_iwpath_helper). My problem is now that I can not simply drop the (q), because without it, the function quote_stripped would get on parameter $1 only the first part of the string, up to the first space (/home/rovf/my).
How can I write this correctly?
I think you just want to avoid trying to strip quotes manually, and use the (Q) expansion flag. Compare:
% v="a b c d"
% echo "$v"
a b c d
% echo "${(q)v}"
a\ b\ c\ d
% echo "${(Q)${(q)v}}"
a b c d
chepner was right: The way I tried to unquote the string was silly (I was thinking too much in a "Bourne Shell way"), and I should have used the (Q) flag.
Here is my solution:
target="${(Q)$(_iwpath_helper)}"
No need for the quote_stripped function anymore....
I run R on Windows, and have a csv file on the Desktop. I load it as follows,
x<-read.csv("C:\Users\surfcat\Desktop\2006_dissimilarity.csv",header=TRUE)
but the R gives the following error message
Error: '\U' used without hex digits in character string starting "C:\U"
So what's the correct way to load this file. I am using Vista
replace all the \ with \\.
it's trying to escape the next character in this case the U so to insert a \ you need to insert an escaped \ which is \\
Please do not mark this response as correct as smitec has already answered correctly. I'm including a convenience function I keep in my .First library that makes converting a windows path to the format that works in R (the methods described by Sacha Epskamp). Simply copy the path to your clipboard (ctrl + c) and then run the function as pathPrep(). No need for an argument. The path is printed to your console correctly and written to your clipboard for easy pasting to a script. Hope this is helpful.
pathPrep <- function(path = "clipboard") {
y <- if (path == "clipboard") {
readClipboard()
} else {
cat("Please enter the path:\n\n")
readline()
}
x <- chartr("\\", "/", y)
writeClipboard(x)
return(x)
}
Solution
Try this: x <- read.csv("C:/Users/surfcat/Desktop/2006_dissimilarity.csv", header=TRUE)
Explanation
R is not able to understand normal windows paths correctly because the "\" has special meaning - it is used as escape character to give following characters special meaning (\n for newline, \t for tab, \r for carriage return, ..., have a look here ).
Because R does not know the sequence \U it complains. Just replace the "\" with "/" or use an additional "\" to escape the "\" from its special meaning and everything works smooth.
Alternative
On windows, I think the best thing to do to improve your workflow with windows specific paths in R is to use e.g. AutoHotkey which allows for custom hotkeys:
define a Hotkey, e.g. Cntr-Shift-V
assigns it an procedure that replaces backslashes within your Clipboard with
slaches ...
when ever you want to copy paste a path into R you can use Cntr-Shift-V instead of Cntr-V
Et-voila
AutoHotkey Code Snippet (link to homepage)
^+v::
StringReplace, clipboard, clipboard, \, /, All
SendInput, %clipboard%
My Solution is to define an RStudio snippet as follows:
snippet pp
"`r gsub("\\\\", "\\\\\\\\\\\\\\\\", readClipboard())`"
This snippet converts backslashes \ into double backslashes \\. The following version will work if you prefer to convert backslahes to forward slashes /.
snippet pp
"`r gsub("\\\\", "/", readClipboard())`"
Once your preferred snippet is defined, paste a path from the clipboard by typing p-p-TAB-ENTER (that is pp and then the tab key and then enter) and the path will be magically inserted with R friendly delimiters.
Replace back slashes \ with forward slashes / when running windows machine
I know this is really old, but if you are copying and pasting anyway, you can just use:
read.csv(readClipboard())
readClipboard() escapes the back-slashes for you. Just remember to make sure the ".csv" is included in your copy, perhaps with this:
read.csv(paste0(readClipboard(),'.csv'))
And if you really want to minimize your typing you can use some functions:
setWD <- function(){
setwd(readClipboard())
}
readCSV <- function(){
return(readr::read_csv(paste0(readClipboard(),'.csv')))
}
#copy directory path
setWD()
#copy file name
df <- readCSV()
Replacing backslash with forward slash worked for me on Windows.
The best way to deal with this in case of txt file which contains data for text mining (speech, newsletter, etc.) is to replace "\" with "/".
Example:
file<-Corpus(DirSource("C:/Users/PRATEEK/Desktop/training tool/Text Analytics/text_file_main"))
I think that R is reading the '\' in the string as an escape character. For example \n creates a new line within a string, \t creates a new tab within the string.
'\' will work because R will recognize this as a normal backslash.
readClipboard() works directly too. Copy the path into your clipboard
C:\Users\surfcat\Desktop\2006_dissimilarity.csv
Then
readClipboard()
appears as
[1] "C:\\Users\\surfcat\\Desktop\\2006_dissimilarity.csv"
A simple way is to use python.
in python terminal type
r"C:\Users\surfcat\Desktop\2006_dissimilarity.csv"
and you'll get back
'C:\Users\surfcat\Desktop\2006_dissimilarity.csv'