I have read some questions and answers on this topic in stack overflow but still don't know how to solve this problem:
My purpose is to transform the file directory strings in windows explorer to the form which is recognizable in R, e.g. C:\Users\Public needs to be transformed to C:/Users/Public, basically the single back slash should be substituted with the forward slash. However the R couldn't store the original string "C:\Users\Public" because the \U and \P are deemed to be escape character.
dirTransformer <- function(str){
str.trns <- gsub("\\", "/", str)
return(str.trns)
}
str <- "C:\Users\Public"
dirTransformer(str)
> Error: '\U' used without hex digits in character string starting ""C:\U"
What I am actually writing is a GUI, where the end effect is, the user types or pastes the directory into a entry field, pushes a button and then the program will process it automatically.
Would someone please suggest to me how to solve this problem?
When you need to use a backslash in the string in R, you need to put double backslash. Also, when you use gsub("\\", "/", str), the first argument is parsed as a regex, and it is not valid as it only contains a single literal backslash that must escape something. In fact, you need to make gsub treat it as a plain text with fixed=TRUE.
However, you might want to use normalizePath, see this SO thread.
dirTransformer <- function(str){
str.trns <- gsub("\\\\", "/", str)
return(str.trns)
}
str <- readline()
C:\Users\Public
dirTransformer(str)
I'm not sure how you intend the user to input the path into the GUI, but when using readline() and then typing C:\Users\Public unquoted, R reads that in as:
> str
[1] "C:\\Users\\Public"
We then want to replace "\\" with "/", but to escape the "\\" we need "\\\\" in the gsub.
I can't be sure how the input from the user is going to be read into R in your GUI, but R will most likely escape the \s in the string like it does when using the readline example. the string you're trying to create "C:\Users\Public" wouldn't normally happen.
Related
unable to enclose "hey" in double quotes within a string . I am unable to get output as Hey "Hey"
ad<- "hey"
fd<- paste("Hey","",ad,sep="")
The dQuote function is made for this:
dQuote("hey")
# [1] "\"hey\""
Note that depending on the OS and your environment, it might add "fancy quotes" (angled/directional double-quotes). They may look good but if you want to reuse the results as a string in R, it won't work because R does not recognize its smart quotes as string-boundaries. You can explicitly disable it with dQuote(., q=FALSE). (The default is FALSE on windows except for the Rgui console, but I believe the default is TRUE elsewhere.)
Depending on your need, you may also like shQuote due to its escaping of existing embedded quotes:
cat(dQuote('"hey" there'), "\n")
# ""hey" there" # may not be right
cat(shQuote('"hey" there'), "\n")
# "\"hey\" there"
though whether that is correct depends on your needs; shQuote was designed for shell-quoting/escaping.
Ultimately in your example, I think you would use
ad <- "Hey"
paste("Hey", dQuote(ad))
# [1] "Hey \"Hey\""
Double quotes can be added with
paste0('"', "Hey", '"')
#[1] "\"Hey\""
Or
sprintf('"%s"', "Hey")
#[1] "\"Hey\""
Note that R displays strings with double quotes (") so to show double quotes as part of string it escapes it with backslash \. To see actual string you may use cat on it.
cat(paste0('"', "Hey", '"'))
#"Hey"
You can write raw strings like:
r"{"Hey"}"
r'{"Hey"}'
[1] "\"hey\""
See ?Quotes
Raw character constants are also available using a syntax similar to the one used in C++: r"(...)" with ... any character sequence, except that it must not contain the closing sequence )". The delimiter pairs [] and {} can also be used, and R can be used in place of r. For additional flexibility, a number of dashes can be placed between the opening quote and the opening delimiter, as long as the same number of dashes appear between the closing delimiter and the closing quote.
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 need to change "/" into "\" in my R code. I have something like this:
tmp <- paste(getwd(),"tmp.xls",sep="/")
so my tmp is c:/Study/tmp.xls
and I want it to be: c:\Study\tmp.xls
Is it possible to change it in R?
Update as per comments.
If this is simply to save the file, then as #sgibb suggested, you are better off using file.path():
file.path(getwd(), "tmp.xls")
Update 2: You want double back-slashes.
tmp is a string and if you want to have an actual backslash you need to escape it -- with a backslash.
However, when R interprets the double slashes (for example, when looking for a file with the path indicated by the string), it will treat the seemingly double slashes as one.
Take a look at what happens when you output the string with cat()
cat("c:\\Study\\tmp.xls")
c:\Study\tmp.xls
The second slash has "disappeared"
Original Answer:
in R, \ is an escape character, thus if you want to print it literally, you need to escape the escape character: \\. This is what you want to put in your paste statement.
You can also use .Platform$file.sep as your sep argument, which will make your code much more portable.
tmp <- paste(getwd(),"tmp.xls",sep=.Platform$file.sep)
If you already have a string you would like to replace, you can use
gsub("/", "\\", tmp, fixed=TRUE)
Windows copies path with backslash \, which R does not accept. So, I wanted to write a function which would convert \ to /. For example:
chartr0 <- function(foo) chartr('\','\\/',foo)
Then use chartr0 as...
source(chartr0('E:\RStuff\test.r'))
But chartr0 is not working. I guess, I am unable to escape /. I guess escaping / may be important in many other occasions.
Also, is it possible to avoid the use chartr0 every time, but convert all path automatically by creating an environment in R which calls chartr0 or use some kind of temporary use like using options
From R 4.0.0 you can use r"(...)" to write a path as raw string constant, which avoids the need for escaping:
r"(E:\RStuff\test.r)"
# [1] "E:\\RStuff\\test.r"
There is a new syntax for specifying raw character constants similar to the one used in C++: r"(...)" with ... any character sequence not containing the sequence )". This makes it easier to write strings that contain backslashes or both single and double quotes. For more details see ?Quotes.
Your fundamental problem is that R will signal an error condition as soon as it sees a single back-slash before any character other than a few lower-case letters, backslashes themselves, quotes or some conventions for entering octal, hex or Unicode sequences. That is because the interpreter sees the back-slash as a message to "escape" the usual translation of characters and do something else. If you want a single back-slash in your character element you need to type 2 backslashes. That will create one backslash:
nchar("\\")
#[1] 1
The "Character vectors" section of _Intro_to_R_ says:
"Character strings are entered using either matching double (") or single (') quotes, but are printed using double quotes (or sometimes without quotes). They use C-style escape sequences, using \ as the escape character, so \ is entered and printed as \, and inside double quotes " is entered as \". Other useful escape sequences are \n, newline, \t, tab and \b, backspace—see ?Quotes for a full list."
?Quotes
chartr0 <- function(foo) chartr('\\','/',foo)
chartr0('E:\\RStuff\\test.r')
You cannot write E:\Rxxxx, because R believes R is escaped.
The problem is that every single forward slash and backslash in your code is escaped incorrectly, resulting in either an invalid string or the wrong string being used. You need to read up on which characters need to be escaped and how. Take a look at the list of escape sequences in the link below. Anything not listed there (such as the forward slash) is treated literally and does not require any escaping.
http://cran.r-project.org/doc/manuals/R-lang.html#Literal-constants
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'