# [R] How to convert backslash to slash?

Shengqiao Li shli at stat.wvu.edu
Wed Sep 24 15:59:16 CEST 2008

On Wed, 24 Sep 2008, jim holtman wrote:

> It probably depends on how you are prompting the user for input.  Here
> is what happens with 'readline' and you will see that the string after
> input does have the backslashes escaped.
>
>> x <- readline("Input File: ")
> Input File: c:\dir1\dir2\file.name
>> x
> [1] "c:\\dir1\\dir2\\file.name"
>> gsub("\\\\", "/", x)  # notice the double escape
> [1] "c:/dir1/dir2/file.name"
>>

Great! Thanks. By the way, it would be nice if R have a third way to quote
a string and automatically escape the backslashes in memory. For instance:

#not run now
s<- C:\Acer'

print(s)
[1] "C:\\Acer"

>
>
> On Wed, Sep 24, 2008 at 8:53 AM, Shengqiao Li <shli at stat.wvu.edu> wrote:
>>
>> On Wed, 24 Sep 2008, Duncan Murdoch wrote:
>>
>>> Shengqiao Li wrote:
>>>>
>>>> On Tue, 23 Sep 2008, Duncan Murdoch wrote:
>>>>
>>>>
>>>>> On 23/09/2008 4:00 PM, Shengqiao Li wrote:
>>>>>
>>>>>> How to use sub, gsub, etc. to replace "\" in a string to "/"?
>>>>>>
>>>>>> For example,convert "C:\foo\bar" to "C:/foo/bar".
>>>>>>
>>>>> If those are R strings, there are no backslashes in the first one.  It
>>>>> has a formfeed and a backspace in it.
>>>>>
>>>>
>>>> I did notice that this string  was special. It's a legimate R string. If
>>>> "f" and "b" are replaced by "d", it will not.
>>>
>>> I didn't say it was not legitimate, I said that it contains no
>>> backslashes. If you replace f or b with d, you do not have a legitimate
>>> string.
>>>>
>>>> My purpose is to convert a Windows file path (eg. copied from Explorer
>>>> location bar) to a R file path through some R function inside R terminal.
>>>> The "File->Change dir..." takes a file path like "C:\Acer", but setwd
>>>> function will fail.
>>>
>>> That's not true.  If you enter a backslash in the string, setwd() works
>>> fine.
>>>
>>> Your problem is that you are confusing R source code with the strings that
>>> it represents.  The R source code for the file path C:\Acer is "C:\\Acer".
>>>  The
>>> R source code "C:\foo\bar" contains no backslashes, it contains the
>>> characters C, :, formfeed, o, o,  backspace, a, r.
>>>
>>> If you have the string C:\Acer in the Windows clipboard, then you can read
>>> it from there using readClipboard().  (There are many other ways to read the
>>> clipboard as well;
>>> using 'clipboard' as a filename generally works.) You can then pass it to
>>> setwd(), and it will be fine.
>>
>> Thank you for your reply. readClipboard is a partial solution to this case.
>> More generally, if I want to wrtie a R program in which users are asked to
>> input a file path. I want this program to be robust and tolerant, that is
>> users can type in C:\Acer or C:/Acer.  What's the way to do this?
>>
>> Shengqiao Li
>>
>>>
>>> Duncan Murdoch
>>>>
>>>> I guess there must be some ways in R to replace a backslash by slash, eg.
>>>> C:\Acer -> C:/Acer. The first problem may be how to pass and save this kind
>>>> of strings. encodeString does not work for this, it will just ignore "\".
>>>>  Shengqiao Li
>>>>
>>>>
>>>>> Duncan Murdoch
>>>>>
>>>>>
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> PLEASE do read the posting guide
>>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>>
>>>
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem that you are trying to solve?
>

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