similar to: Large regular expressions

Displaying 20 results from an estimated 9000 matches similar to: "Large regular expressions"

2008 Aug 10
2
Basic data structures
I'm new to R and very excited about its possibilities. But I'm struggling with some very simple things, probably because I haven't found the correct documentation. Here's a simple example which illustrates several of my problems. Suppose I want to have a regexp match against a string, and return all the matching substrings in a vector of strings. regexp <-
2009 Mar 09
3
E`<`<rrors in recursive default argument references
Tested in: R version 2.8.1 (2008-12-22) / Windows Recursive default argument references normally give nice clear errors. In the first set of examples, you get the error: Error in ... : promise already under evaluation: recursive default argument reference or earlier problems? (function(a = a) a ) () (function(a = a) c(a) ) () (function(a = a) a[1] ) () (function(a = a)
2008 Nov 29
2
Using grep() to subset lines of text
I have two vectors, a and b. b is a text file. I want to find in b those elements of a which occur at the beginning of the line in b. I have the following code, but it only returns a value for the first value in a, but I want both. Any ideas please. a = c(2,3) b = NULL b[1] = "aaa 2 aaa" b[2] = "2 aaa" b[3] = "3 aaa" b[4] = "aaa 3 aaa"
2009 Feb 17
2
cumsum vs. sum
I recently traced a bug of mine to the fact that cumsum(s)[length(s)] is not always exactly equal to sum(s). For example, x<-1/(12:14) sum(x) - cumsum(x)[3] => 2.8e-17 Floating-point addition is of course not exact, and in particular is not associative, so there are various possible reasons for this. Perhaps sum uses clever summing tricks to get more accurate results? In some
2009 Jul 29
3
Object equality for S4 objects
To test two environments for object equality (Lisp EQ), I can use 'identity': > e1 <- environment(local(function()x)) > e2 <- environment(local(function()x)) > identical(e1,e2) # compares object identity [1] FALSE > identical(as.list(e1),as.list(e2)) # compares values as name->value mapping [1] TRUE # (is there a
2009 May 20
2
Class for time of day?
What is the recommended class for time of day (independent of calendar date)? And what is the recommended way to get the time of day from a POSIXct object? (Not a string representation, but a computable representation.) I have looked in the man page for DateTimeClasses, in the Time Series Analysis Task View and in Spector's Data Manipulation book but haven't found these. Clearly I can
2009 Jun 23
1
Documentation/software inconsistency in `:` and seq
In 2.8.1/Windows: According to ? : Details: For numeric arguments 'from:to' is equivalent to 'seq(from, to)' ... Value: For numeric arguments, a numeric vector. This will be of type 'integer' if 'from' and 'to' are both integers and representable in the integer type, otherwise of type 'numeric'.... The first claim
2009 Feb 08
3
Best 64-bit Linux distro for R?
The R FAQ is very helpful about installing R on various Linuxes, but doesn't seem to discuss the advantages of one distribution over another. I am new to Linux (though not to Unix!), and would appreciate some guidance from those with experience. I plan to set up a headless Linux x86 server for the sole purpose of running 64-bit R. Are there reasons to prefer some Linux distributions over
2009 Feb 10
1
Variable/function namespaces WAS: Bug in subsetting data frame (PR#13515)
On Tue, Feb 10, 2009 at 10:11 AM, Duncan Murdoch <murdoch at stats.uwo.ca> wrote: > Stavros Macrakis wrote: >> On Tue, Feb 10, 2009 at 8:31 AM, Duncan Murdoch <murdoch at stats.uwo.ca>wrote: >>> The evaluator recognizes the context of usage and will get the >>> function for a function call.... >> Can you point me to chapter and verse in the language
2009 Dec 18
2
Vectorized switch
What is the 'idiomatic' way of writing a vectorized switch statement? That is, I would like to write, e.g., vswitch( c('a','x','b','a'), a= 1:4, b=11:14, 100 ) => c(1, 100, 13, 4 ) equivalent to ifelse( c('a','x','b','a') ==
2011 Oct 19
2
Speed difference between df$a[1] and df[1,"a"]
I was surprised to find that df$a[1] is an order of magnitude faster than df[1,"a"]: > df <- data.frame(a=1:10) > system.time(replicate(100000, df$a[3])) user system elapsed 0.36 0.00 0.36 > system.time(replicate(100000, df[3,"a"])) user system elapsed 4.09 0.00 4.09 A priori, I'd have thought that combining the row and column
2009 Apr 20
2
The assign(paste(...,i),...) idiom
Judging from the traffic on this mailing list, a lot of R beginners are trying to write things like assign( paste( "myvar", i), ...) where they really should probably be writing myvar[i] <- ... Do we have any idea where this bizarre habit comes from? -s
2009 Mar 23
2
dput(as.list(function...)...) bug
Tested in R 2.8.1 Windows > ff <- formals(function(x)1) > ff1 <- as.list(function(x)1)[1] # ff1 acts the same as ff in the examples below, but is a list rather than a pairlist > dput( ff , control=c("warnIncomplete")) list(x = ) This string is not parsable, but dput does not give a warning as specified. > dput( ff ,
2008 Dec 08
4
R and Scheme
I've read in many places that R semantics are based on Scheme semantics. As a long-time Lisp user and implementor, I've tried to make this more precise, and this is what I've found so far. I've excluded trivial things that aren't basic semantic issues: support for arbitrary-precision integers; subscripting; general style; etc. I would appreciate corrections or additions from
2011 Apr 04
2
General binary search?
Is there a generic binary search routine in a standard library which a) works for character vectors b) runs in O(log(N)) time? I'm aware of findInterval(x,vec), but it is restricted to numeric vectors. I'm also aware of various hashing solutions (e.g. new.env(hash=TRUE) and fastmatch), but I need the greatest-lower-bound match in my application. findInterval is also slow for
2009 May 27
1
R Books listing on R-Project
I was wondering what the criteria were for including books on the Books Related to R page <http://www.r-project.org/doc/bib/R-books.html>. (There is no maintainer listed on this page.) In particular, I was wondering why the following two books are not listed: * Andrew Gelman, Jennifer Hill, *Data Analysis Using Regression and Multilevel/Hierarchical Models*. (CRAN package 'arm') *
2009 Jun 26
3
Automatically placing a legend in an area with the most white space...
At one point I believe I heard of an R package that would automatically find the most empty space in a plot, and then that answer could then be used to intelligently place a legend. I would like to try to apply that R package to the contrived example shown below, so thank you for any hints or tips that can be provided. x = seq(0, 1000, by = 1) y1_vals<-rnorm(1000, mean = 0, sd = 50)
2009 Apr 01
2
Definition of = vs. <-
NOTA BENE: This email is about `=`, the assignment operator (e.g. {a=1} which is equivalent to { `=`(a,1) } ), not `=` the named-argument syntax (e.g. f(a=1), which is equivalent to eval(structure(quote(f(1)),names=c('','a'))). As far as I can tell from the documentation, assignment with = is precisely equivalent to assignment with <-. Yet they call different primitives: >
2009 Apr 01
2
Definition of = vs. <-
NOTA BENE: This email is about `=`, the assignment operator (e.g. {a=1} which is equivalent to { `=`(a,1) } ), not `=` the named-argument syntax (e.g. f(a=1), which is equivalent to eval(structure(quote(f(1)),names=c('','a'))). As far as I can tell from the documentation, assignment with = is precisely equivalent to assignment with <-. Yet they call different primitives: >
2009 Jun 19
3
Floating point precision / guard digits? (PR#13771)
Full_Name: D Kreil Version: 2.8.1 and 2.9.0 OS: Debian Linux Submission from: (NULL) (141.244.140.179) Group: Accuracy I understand that most floating point numbers are approximated due to their binary storage. On the other hand, I thought that modern math CPUs used guard digits to protect against trivial underflows. Not true? # integers, no problem > 1+1+1==3 [1] TRUE # binary floating