similar to: help with sockets in R

I am curious why readLines() has a default (n=-1L) to read the full file while readChar() has no default for nchars= (i.e., readChar(file) is an error). Is there a technical reason for this? I often[1] see code like paste(readLines(f), collapse="\n") which would be better served by readChar(), especially given issues with the global string cache I've come across[2]. But lacking the

On Fri, 26 Jan 2024, Michael Chirico wrote: > I am curious why readLines() has a default (n=-1L) to read the full > file while readChar() has no default for nchars= (i.e., readChar(file) > is an error). Is there a technical reason for this? > > I often[1] see code like paste(readLines(f), collapse="\n") which > would be better served by readChar(), especially given

My opinion is that the proposed feature would be greatly appreciated by users. I had always wondered if I was the only one doing paste(readLines(f), collapse="\n") all the time. It would be great to have the proposed, more straightforward way to read the whole file as a string: readChar("my_file.txt", -1) or even better readChar("my_file.txt") Thanks for your detailed

Hi, Here's a patch to the readChar manual page (R-trunk as of today) that better clarifies readChar's return value. It could use some work as I'd also like to add some text about using nchar() to find the length of the string that readchar() returns, but I'm unsure which of type="bytes" or type="chars" to mention. Is it type="chars"? Index:

Full_Name: Hugh C. Pumphrey Version: 1.4.1 OS: Linux (Debian Woody) Submission from: (NULL) (129.215.133.170) The function readChar() appears to have some type of problem with memory allocation. I don't know if "memory leak" is the correct term but if one uses readChar() many times, the R binary grows in size until it eats all your memory and swap space. The code enclosed below

I noticed an issue where readChar does not return the correct value after a call to readline. It appears that readChar is not aware of the buffering, so it reads from the end of the buffer, rather than the current position in the file. This is a significant change of behavior from R-3.4.4. Below is a test case that I used to home in on the problem. --- p<-"test2.txt"

Tomas, Thank you for the explanation. I see in the documentation: "These functions are intended to be used with binary-mode connections." So I see how using it on a text connection is undefined, and not a bug. An error or warning when attempting to use a it on a text connection would be helpful considering how the behavior has changed in R-3.5. On Tue, May 29, 2018 at 3:09 AM, Tomas

Hi, I am trying to read in records from an old main frame file. Each record is 640 bytes. I had some success using the following statement: iconv(readChar(con, nchars=640, useBytes = TRUE),from="IBM037",to="",sub="#") What I have found, however, is that ocassionally a record will contain a Null halfway through, which causes readChar() not to read the rest of the

Hi, I am trying to implement messaging protocol that doesn't pre-specify the length of the message in the message header. In other words, I don't know in advance when I will reach the end of the message. I wrote C level parser for strings but when it came to reading from connections I got stuck. API in Connections.h doesn't provide a pointer to an existing connection and there seems

Trying to copy the (binary) header of a input file directly to an output file, I've had repeatable seg faults. The call: writeChar(hdr, outfh, nchars=6144) when hdr just contains one empty string seems to be the culprit. The stack traces weren't all that illuminating, with sig 11 in memory-related functions following this. But in src/main/connections.c it looks like do_writechar

Dear all, I have written a little R program to convert images. See below. Within the loop over j (the filenames) memory consumption grows constantly. rm( ... ) inside the loop did not help. Memory does not grow if I remove the writeBin statements between the two #-------- marks. But obviously this is not solution I want... Thanks for any advice. Manfred Baumstark P.S. As I'm new to R:

Thanks to all who have responded. My concern was to be able to write a csv file that can have line feeds in string columns chr(10). Why? Excel allows line feeds chr(10) within cells and line breaks chr(13)+chr(10) at line ending, but the windows version of R automatically replaces \n by \r\n in writing and \r\n by \n in reading (text mode). The clues for a solution came from Brian Ripley and

Hi, I'm trying to generate valid R code using R. Parts of the task is to read a sequence of characters from file and escape them such that they can be put in quotation marks to form a valid R code string. Example: Let the input file be (four rows containing ASCII 0-255 characters): abcdef<tab>ghijk\nlmno second row\t\a\\ fourth and so on... <EOF> Now, find escapeString() such

Hi, I'm trying to generate valid R code using R. Parts of the task is to read a sequence of characters from file and escape them such that they can be put in quotation marks to form a valid R code string. Example: Let the input file be (four rows containing ASCII 0-255 characters): abcdef<tab>ghijk\nlmno second row\t\a\\ fourth and so on... <EOF> Now, find escapeString() such

Hi. WISHLIST: Regardless on console, I'd like to be able to timeout a call to readline()/file("stdin", blocking=TRUE) via setTimeLimit. OBSERVATION: On Windows Rterm as well as plain R on Linux, setTimeLimit() does not momentarily interrupt from stdin, but only after hitting RETURN. A few examples: timeout00 <- function() { setTimeLimit(elapsed=5); Sys.sleep(10); }

Hello, I am trying to read in elements out of a very large binary file ... the total file is 4 gigs. I want to select rows out of the file, and the current procedure I run works but is prohibitively slow (takes more than a day to run and still won't complete). Is there any faster way to accomplish this? My current procedure looks like this: readHH <- function(file_name,

Hi, I am looking for a way to search a file for position of some expression, from within R. My current code: sha1Pos = gregexpr("<sha1>", readChar(filename, file.info(filename)$size))[[1]] Works fine for small files, but text files I will be working with might get up to Gb range, so I was trying to accomplish the same without loading the whole file into R. I realize this is

I have R code to read a binary header file, consisting of several readBin() and readChar() statements. I am currently using version R-2.2.1 (on x86_64, RH EL4) and have received the following error Error in readChar(fid, n = 1) : invalid UTF-8 input in readChar() This is strange because (a) I was able to read in this file successfully in previous versions of R (circa 2005) and (b) it

Hi all, Since I was having several problems trying to work with a large matrix I started to use the package R.huge but I'm having the following problem > x<-FileByteMatrix("covtype.data",nrow=581012,ncol=55) Error: cannot allocate vector of size 770.8 Mb In addition: Warning messages: 1: Reached total allocation of 447Mb: see help(memory.size) in: readChar(con = con, nchar =

Hi, I was trying to have R read files faster with readChar(). That was before I noticed that readChar() is not that bad! In any case, below I suggest a few simple changes that will make readChar slightly faster. I followed readChar(useBytes=T), and tried to identify all O(N) operations, where N is the size of the file. The assumption is that for LARGE files we want to avoid any O(N) operations,