gsub

问题 I'm trying to replace a certain string in a large data.frame. I just found the following solution but gsub doesn't preserve the original data.frame layout. How can I achieve this. I mean I want to replace a string and don't want to change the layout of the df. Consider this example: test<-data.frame(a=c("a","b","c","d"),b=c("a","e","g","h"),c=c("i","j","k","a")) gsub("a","new",test) Thx 回答1: You will want to lapply through your data.frame testing for character or factor entries and then

问题 I have a matrix that contains the string "Energy per �m". Before the 'm' is a diamond shaped symbol with a question mark in it - I don't know what it is. I have tried to get rid of it by using this on the column of the matrix: a=gsub('Energy per �m','',a) [and using copy/paste for the first term of gsub], but it does not work.[unexpected symbol in "a=rep(5,Energy per"]. When I try to extract something from the original matrix with grepl I get: 46: In grepl("ref. value", raw$parameter) : input

问题 How should I convert a post title to a slug in Ruby? The title can have any characters, but I only want the slug to allow [a-z0-9-_] (Should it allow any other characters?). So basically: downcase all letters convert spaces to hyphens delete extraneous characters 回答1: slug = title.downcase.strip.gsub(' ', '-').gsub(/[^\w-]/, '') downcase makes it lowercase. The strip makes sure there is no leading or trailing whitespace. The first gsub replaces spaces with hyphens. The second gsub removes all

问题 I have the following vector: x <- c(11, 12, 21, 22) And I want to convert it to the corresponding letters, i.e., I want to get this result: AA AB BA BB How do I make this? I bet there's a simple answer and that it goes through using the reserved LETTERS vector, but I can't figure out a solution. This is the best I've managed to come up with so far (you might want to take the kids out of the room): > paste0(gsub(1, LETTERS[1], substr(x, 1, 1)), gsub(2, LETTERS[2], substr(x, 1, 1))) [1] "A1"

问题 I have the following vector: x <- c(11, 12, 21, 22) And I want to convert it to the corresponding letters, i.e., I want to get this result: AA AB BA BB How do I make this? I bet there's a simple answer and that it goes through using the reserved LETTERS vector, but I can't figure out a solution. This is the best I've managed to come up with so far (you might want to take the kids out of the room): > paste0(gsub(1, LETTERS[1], substr(x, 1, 1)), gsub(2, LETTERS[2], substr(x, 1, 1))) [1] "A1"

问题 I need to match a line in an inputted text file string and wrap that captured line with a character for example. For example imagine a text file as such: test foo test bar I would like to use gsub to output: XtestX XfooX XtestX XbarX I'm having trouble matching a line though. I've tried using regex starting with ^ and ending with $, but it doesn't seem to work. Any ideas? I have a text file that has the following in it: test foo test bag The text file is being read in as a command line

问题 I am trying to apply gsub in R to replace a match in string a with the corresponding match in string b. For example: a <- c("don't", "i'm", "he'd") b <- c("do not", "i am", "he would") c <- c("i'm going to the party", "he'd go too") newc <- gsub(a, b, c) such that newc = "i am going to the party", "he would go too") This approach does not work because gsub only accepts a string of length 1 for a and b. Executing a loop to cycle through a and b will be very slow since the real a and b have a

问题 I've been trying to remove the white space that I have in a data frame (using R) . The data frame is large (>1gb) and has multiple columns that contains white space in every data entry. Is there a quick way to remove the white space from the whole data frame? I've been trying to do this on a subset of the first 10 rows of data using: gsub( " ", "", mydata) This didn't seem to work, although R returned an output which I have been unable to interpret. str_replace( " ", "", mydata) R returned 47

问题 I want to replace dots in "2014.06.09" to "2014-06-09" . I am using gsub() function for it. If x <- "2014.06.09" gsub('2', '-' ,x) # [1] "-014.06.09" But when I try gsub('.', '-', x) # [1] "----------" instead of "2014-06-09" . class(x) # "character" Can some suggest me a way to get this right and also why it is not working for '.' (dot) 回答1: You may need to escape the . which is a special character that means "any character" (from @Mr Flick's comment) gsub('\\.', '-', x) #[1] "2014-06-09" Or

问题 I want to replace dots in "2014.06.09" to "2014-06-09" . I am using gsub() function for it. If x <- "2014.06.09" gsub('2', '-' ,x) # [1] "-014.06.09" But when I try gsub('.', '-', x) # [1] "----------" instead of "2014-06-09" . class(x) # "character" Can some suggest me a way to get this right and also why it is not working for '.' (dot) 回答1: You may need to escape the . which is a special character that means "any character" (from @Mr Flick's comment) gsub('\\.', '-', x) #[1] "2014-06-09" Or