The string is
And I want to get substrings "11","1.1","282". Can anyone show me how to do this in R? Thanks!
I believe strsplit(x," +")[[1]] will do it. (the regular expression " +" denotes one or more spaces; strsplit applies to character vectors, and returns a list with the splitted version of each element in the vector, so [[1]] extracts the first (and only) component)
> x = "11 1.1 282"
> res <- strsplit(x, " +")
> res
[[1]]
[1] "11" "1.1" "282"
>
Related
I'm making a graphing calculator in Unity and I have input with strings like "3+10" and I want to split it to "3","+" and "10".
I can figure out a way to deal with them once I've got them to this form, but I really need a way to split the string to the left and right of key characters such as plus, times, exponent, etc.
I'm doing this in Unity, but a way to do this in any language should help.
C#
The following code will do what you asked for (and nothing more).
string input = "3+10-5";
string pattern = #"([-+^*\/])";
string[] substrings = Regex.Split(input, pattern);
// results in substrings = {"3", "+", "10", "-", "5"}
By using Regex.Split instead of String.Split you are able to retrieve the math operators as well. This is done by putting the math operators in a capture group ( ). If you're not familiar with regular expressions you should google the basics.
The code above will stubbornly use the math operators to split your string. If the string doesn't make sense, the method doesn't care and may even produce unexpected results. For example "5//10-" will result in {"5", "/", "", "10", "-", ""}. Note that only one / is returned and empty strings are added.
You can use more complex regular expressions to check if your string is a valid mathematical expression before you try to split it. For example ^(\d+(?:.\d+)?+([-+*^\/]\g<1>)?)$ would check if your string consists of a decimal number and zero or more combinations of an operator and another decimal number.
Here is the C# way -- which I mention because you are using Unity.
words = phrase.Split(default(string[]),StringSplitOptions.RemoveEmptyEntries);
https://msdn.microsoft.com/en-us/library/tabh47cf%28v=vs.110%29.aspx
Here is Java code for splitting a String by math operators
String[] splitByOperators(String input) {
String[] output = new String[input.length()];
int index = 0;
String current = "";
for (char c : input){
if (c == '+' || c == '-' || c == '*' || c == '/'){
output[index] = current;
index++;
output[index] = c;
index++;
current = "";
} else {
current = current + c;
}
}
output[index] = current;
return output;
}
Using Python regular expressions:
>>> import re
>>> match = re.search(r'(\d+)(.*)(\d+)', "3+1")
>>> match.group(1)
'3'
>>> match.group(2)
'+'
>>> match.group(3)
'1'
The reason for using regular expressions is for greater flexibility in handling a variety of simple arithmetic expressions.
R: EDITED
Take your input vector as x<-c("3+10", "4/12" , "8-3" ,"12*1","1+2-3*4/8").
We can use the following string split based on regex:
> strsplit(x,split="(?<=\\d)(?=[+*-/])|(?<=[+*-/])(?=\\d)",perl=T)
[[1]]
[1] "3" "+" "10"
[[2]]
[1] "4" "/" "12"
[[3]]
[1] "8" "-" "3"
[[4]]
[1] "12" "*" "1"
[[5]]
[1] "1" "+" "2" "-" "3" "*" "4" "/" "8"
How it works:
Split the string when one of two things is found:
A digit followed by an arithmetic operator. (?<=\\d) finds something immediately preceded by a digit, while (?=[+*-/]) finds something immediately succeeded by an arithmetic operator, i.e. +, *, -, or /. The "something" in both cases is the blank string "" found between a digit and an operator, and the string is split at such a point.
An arithmetic operator followed by a digit. This is just the reverse of the above.
Suppose I have a string like:
x<-c("bv_bid_bayley_inf_development_f7r","bv_fci_family_care_indicator_f7r")
how can I position the first "_" (a) and the last "_" (b) so that I can substr(x,a,b) in R. Such a output like that:
bid_bayley_inf_development
fci_family_care_indicator
You can use regular expressions to extract the substring:
x <- c("bv_bid_bayley_inf_development_f7r", "bv_fci_family_care_indicator_f7r")
sub("[^_]*_(.*)_[^_]*", "\\1", x)
# [1] "bid_bayley_inf_development" "fci_family_care_indicator"
for position only,
gregexpr("_",x)
Long strings in plots aren't always attractive. What's the shortest way of making an acronym in R? E.g., "Hello world" to "HW", and preferably to have unique acronyms.
There's function abbreviate, but it just removes some letters from the phrase, instead of taking first letters of each word.
An easy way would be to use a combination of strsplit, substr, and make.unique.
Here's an example function that can be written:
makeInitials <- function(charVec) {
make.unique(vapply(strsplit(toupper(charVec), " "),
function(x) paste(substr(x, 1, 1), collapse = ""),
vector("character", 1L)))
}
Test it out:
X <- c("Hello World", "Home Work", "holidays with children", "Hello Europe")
makeInitials(X)
# [1] "HW" "HW.1" "HWC" "HE"
That said, I do think that abbreviate should suffice, if you use some of its arguments:
abbreviate(X, minlength=1)
# Hello World Home Work holidays with children Hello Europe
# "HlW" "HmW" "hwc" "HE"
Using regex you can do following. The regex pattern ((?<=\\s).|^.) looks for any letter followed by space or first letter of the string. Then we just paste resulting vectors using collapse argument to get first letter based acronym. And as Ananda suggested, if you want to make unique pass the result through make.unique.
X <- c("Hello World", "Home Work", "holidays with children")
sapply(regmatches(X, gregexpr(pattern = "((?<=\\s).|^.)", text = X, perl = T)), paste, collapse = ".")
## [1] "H.W" "H.W" "h.w.c"
# If you want to make unique
make.unique(sapply(regmatches(X, gregexpr(pattern = "((?<=\\s).|^.)", text = X, perl = T)), paste, collapse = "."))
## [1] "H.W" "H.W.1" "h.w.c"
This question already has answers here:
How do I specify a dynamic position for the start of substring?
(4 answers)
Closed 5 years ago.
I have a list of strings in R which looks like:
WDN.TO
WDR.N
WDS.AX
WEC.AX
WEC.N
WED.TO
I want to get all the postfix of the strings starting from the character ".", the result should look like:
.TO
.N
.AX
.AX
.N
.TO
Anyone have any ideas?
Joshua's solution works fine. I'd use sub instead of gsub though. gsub is for substituting multiple occurrences of a pattern in a string - sub is for one occurrence. The pattern can be simplified a bit too:
> x <- c("WDN.TO","WDR.N","WDS.AX","WEC.AX","WEC.N","WED.TO")
> sub("^[^.]*", "", x)
[1] ".TO" ".N" ".AX" ".AX" ".N" ".TO"
...But if the strings are as regular as in the question, then simply stripping the first 3 characters should be enough:
> x <- c("WDN.TO","WDR.N","WDS.AX","WEC.AX","WEC.N","WED.TO")
> substring(x, 4)
[1] ".TO" ".N" ".AX" ".AX" ".N" ".TO"
Using gsub:
x <- c("WDN.TO","WDS.N")
# replace everything from the start of the string to the "." with "."
gsub("^.*\\.",".",x)
# [1] ".TO" ".N"
Using strsplit:
# strsplit returns a list; use sapply to get the 2nd obs of each list element
y <- sapply(strsplit(x,"\\."), `[`, 2)
# since we split on ".", we need to put it back
paste(".",y,sep="")
# [1] ".TO" ".N"
Strsplit might do it but in case the data set is too large it will show an error
subscript out of bounds
x <- c("WDN.TO","WDR.N","WDS.AX","WEC.AX","WEC.N","WED.TO")
y <- strsplit(x,".")[,2]
#output y= TO N AX AX N TO
I would like to convert the a string like be33szfuhm100060 into BESZFUHM0060.
In order to replace the small letters with capital letters I've so far used the gsub function.
test1=gsub("be","BE",test)
Is there a way to tell this function to replace the 3rd and 4th string element? If not, I would really appreciate if you could tell me another way to solve this problem. Maybe there is also a more general solution to change a string element at a certain position into a capital letter whatever the element is?
A couple of observations:
Cnverting a string to uppercase can be done with toupper, e.g.:
> toupper('be33szfuhm100060')
> [1] "BE33SZFUHM100060"
You could use substr to extract a substring by character positions and paste to concatenate strings:
> x <- 'be33szfuhm100060'
> paste(substr(x, 1, 2), substr(x, 5, nchar(x)), sep='')
[1] "beszfuhm100060"
As an alternative, if you are going to be doing this alot:
String <- function(x="") {
x <- as.character(paste(x, collapse=""))
class(x) <- c("String","character")
return(x)
}
"[.String" <- function(x,i,j,...,drop=TRUE) {
unlist(strsplit(x,""))[i]
}
"[<-.String" <- function(x,i,j,...,value) {
tmp <- x[]
tmp[i] <- String(value)
x <- String(tmp)
x
}
print.String <- function(x, ...) cat(x, "\n")
## try it out
> x <- String("be33szfuhm100060")
> x[3:4] <- character(0)
> x
beszfuhm100060
You can use substring to remove the third and fourth elements.
x <- "be33szfuhm100060"
paste(substring(x, 1, 2), substring(x, 5), sep = "")
If you know what portions of the string you want based on their position(s), use substr or substring. As I mentioned in my comment, you can use toupper to coerce characters to uppercase.
paste( toupper(substr(test,1, 2)),
toupper(substr(test,5,10)),
substr(test,12,nchar(test)),sep="")
# [1] "BESZFUHM00060"