Let's say we have a url in R like:
url <- 'http://google.com/maps'
And the objective is to change the 'maps' part of it. I'd like to write a function where basically I can just input something (e.g. 'maps', 'images'), etc., and the relevant part of the url will automatically change to reflect what I'm typing in.
Is there a way to do this in R, where part of the url can be changed by typing something into a function?
Thanks!
You have to store the part you type into a variable and paste this to the base URL:
base_url <- "http://google.com/"
your_extension <- "maps"
paste0(base_url, your_extension)
[1] "http://google.com/maps"
If you have to start with a fixed URL, use sub to replace the last part:
sub("\\w+$", 'foo', url)
# "http://google.com/foo"
You can use dirname to remove the last part of the URL and paste it with additional custom string.
change_url_part <- function(base_url, string) {
paste(dirname(base_url), string, sep = '/')
}
change_url_part('http://google.com/maps', 'images')
#[1] "http://google.com/images"
Related
I have a line of code in my script that checks if a file exists (actually, many files, this one line gets looped for a bunch of different files):
file.exists(Sys.glob(file.path(getwd(), "files", "*name*")))
This looks for any file in the directory /files/ that has "name" in it, e.g. "filename.csv". However, some of my files are named "fileName.csv" or "thisfileNAME.csv". They do not get recognized. How can i make file.exists treat this check in a case insensitive way?
In my other code i usually make any imported names or lists immediately lowercase with the tolower function. But I don't see any option to include that in the file.exists function.
Suggested solution using list.files:
If we have many files we might want to do this only once, otherwise we can put in in the function (and pass path_to_root_directory instead of found_files to the function)
found_files <- list.files(path_to_root_directory, recursive=FALSE)
Behaviour as file.exists (return value is boolean):
fileExIsTs <- function(file_path, found_files) {
return(tolower(file_path) %in% tolower(found_files))
}
Return value is file with spelling as found in directory or character(0) if no match:
fileExIsTs <- function(file_path, found_files) {
return(found_files[tolower(found_files) %in% tolower(file_path)])
}
Edit:
New solution to fit new requirements:
keywordExists <- function(keyword, found_files) {
return(any(grepl(keyword, found_files, ignore.case=TRUE)))
}
keywordExists("NaMe", found_files=c("filename.csv", "morefilenames.csv"))
Returns:
[1] TRUE
Or
Return value are files with spelling as found in directory or character(0) if no match:
keywordExists2 <- function(file_path, found_files) {
return(found_files[grepl(keyword, found_files, ignore.case=TRUE)])
}
keywordExists2("NaMe", found_files=c("filename.csv", "morefilenames.csv"))
Returns:
[1] "filename.csv" "morefilenames.csv"
The following should return a 1 if the filename matches in any case and a 0 if it does not.
max(grepl("*name*",list.files()),ignore.case=T)
I would like to return "blah".
url <- "https://www.example.com/apples/pears/blah.csv"
I can get blah but I feel like I'm writing more lines of code than I should. Example, to get blah.csv I can do:
url_split <- str_split(url, "/")
dirname <- url_split[[1]][length(url_split[[1]])]
This gives me "blah.csv", where I can do a very similar code block as above to get "blah" by calling str_split again.
Is there a more sophisticated one liner to get the last directory in the url minus ".csv"?
fn <- basename("https://www.example.com/apples/pears/blah.csv")
gsub("\\..*$", "", fn)
Been going around for hours with this. My 1st question online on R. Trying to creat a function that contains a loop. The function takes a vector that the user submits like in pollutantmean(4:6) and then it loads a bunch of csv files (in the directory mentioned) and binds them. What is strange (to me) is that if I assign the variable id and then run the loop without using a function, it works! When I put it inside a function so that the user can supply the id vector then it does nothing. Can someone help ? thank you!!!
pollutantmean<-function(id=1:332)
{
#read files
allfiles<-data.frame()
id<-str_pad(id,3,pad = "0")
direct<-"/Users/ped/Documents/LearningR/"
for (i in id) {
path<-paste(direct,"/",i,".csv",sep="")
file<-read.csv(path)
allfiles<-rbind(allfiles,file)
}
}
Your function is missing a return value. (#Roland)
pollutantmean<-function(id=1:332) {
#read files
allfiles<-data.frame()
id<-str_pad(id,3,pad = "0")
direct<-"/Users/ped/Documents/LearningR/"
for (i in id) {
path<-paste(direct,"/",i,".csv",sep="")
file<-read.csv(path)
allfiles<-rbind(allfiles,file)
}
return(allfiles)
}
Edit:
Your mistake was that you did not specify in your function what you want to get out from the function. In R, you create objects inside of function (you could imagine it as different environment) and then specify which object you want it to return.
With my comment about accepting my answer, I meant this: (...To mark an answer as accepted, click on the check mark beside the answer to toggle it from greyed out to filled in...).
Consider even an lapply and do.call which would not need return being last line of function:
pollutantmean <- function(id=1:332) {
id <- str_pad(id,3,pad = "0")
direct_files <- paste0("/Users/ped/Documents/LearningR/", id, ".csv")
# READ FILES INTO LIST AND ROW BIND
allfiles <- do.call(rbind, lapply(direct_files, read.csv))
}
ok, I got it. I was expecting the files that are built to be actually created and show up in the environment of R. But for some reason they don't. But R still does all the calculations. Thanks lot for the replies!!!!
pollutantmean<-function(directory,pollutant,id)
{
#read files
allfiles<-data.frame()
id2<-str_pad(id,3,pad = "0")
direct<-paste("/Users/pedroalbuquerque/Documents/Learning R/",directory,sep="")
for (i in id2) {
path<-paste(direct,"/",i,".csv",sep="")
file<-read.csv(path)
allfiles<-rbind(allfiles,file)
}
#averaging polutants
mean(allfiles[,pollutant],na.rm = TRUE)
}
pollutantmean("specdata","nitrate",23:35)
I want to create an object in R, which will contain one string, with a few variables (in my case it is file path). When I try to use paste to concatenate the file paths I can see only one last variable instead of all variables in one string. I use next code:
for(i in seq_len(nrow(samples))) {
lib = samples$conditions[i]
txtFile = file.path(lib, "hits.txt")
testfiles = paste(txtFile, sep = ',')
}
print(testfiles)
and get something like
cond/hits.txt,
instead of
cond/hits.txt,cond1/hits.txt,cond2/hits.txt and so on
Thank you very much for help
I now have a full path for a file as a string like:
"/db/Liebherr/Content_Repository/Techpubs/Topics/HyraulicPowerDistribution/Released/TRN_282C_HYD_MOD_1_Drive_Shaft_Rev000.xml"
However, now I need to take out only the folder path, so it will be the above string without the last back slash content like:
"/db/Liebherr/Content_Repository/Techpubs/Topics/HyraulicPowerDistribution/Released/"
But it seems that the substring() function in xQuery only has substring(string,start,len) or substring(string,start), I am trying to figure out a way to specify the last occurence of the backslash, but no luck.
Could experts help? Thanks!
Try out the tokenize() function (for splitting a string into its component parts) and then re-assembling it, using everything but the last part.
let $full-path := "/db/Liebherr/Content_Repository/Techpubs/Topics/HyraulicPowerDistribution/Released/TRN_282C_HYD_MOD_1_Drive_Shaft_Rev000.xml",
$segments := tokenize($full-path,"/")[position() ne last()]
return
concat(string-join($segments,'/'),'/')
For more details on these functions, check out their reference pages:
fn:tokenize()
fn:string-join()
fn:replace can do the job with a regular expression:
replace("/db/Liebherr/Content_Repository/Techpubs/Topics/HyraulicPowerDistribution/Released/TRN_282C_HYD_MOD_1_Drive_Shaft_Rev000.xml",
"[^/]+$",
"")
This can be done even with a single XPath 2.0 (subset of XQuery) expression:
substring($fullPath,
1,
string-length($fullPath) - string-length(tokenize($fullPath, '/')[last()])
)
where $fullPath should be substituted with the actual string, such as:
"/db/Liebherr/Content_Repository/Techpubs/Topics/HyraulicPowerDistribution/Released/TRN_282C_HYD_MOD_1_Drive_Shaft_Rev000.xml"
The following code tokenizes, removes the last token, replaces it with an empty string, and joins back.
string-join(
(
tokenize(
"/db/Liebherr/Content_Repository/Techpubs/Topics/HyraulicPowerDistribution/Released/TRN_282C_HYD_MOD_1_Drive_Shaft_Rev000.xml",
"/"
)[position() ne last()],
""
),
"/"
)
It seems to return the desired result on try.zorba-xquery.com. Does this help?