Aliases: readBinFragments.default readBinFragments
Keywords: IO
### ** Examples # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - # Create a data file # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - data <- 1:255 size <- 2 pathname <- tempfile("exampleReadBinFragments") writeBin(con=pathname, data, size=size) # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - # Read and write using index vectors # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - cat("Read file...\n")
Read file...
# Read every 16:th byte in the file idxs <- seq(from=1, to=255, by=16) x <- readBinFragments(pathname, what="integer", size=size, signed=FALSE, idxs=idxs) stopifnot(identical(x, data[idxs])) print(x)
[1] 1 17 33 49 65 81 97 113 129 145 161 177 193 209 225 241
# Read every 16:th byte in a connection starting with the 6th. idxs <- idxs + 5L x <- readBinFragments(pathname, what="integer", size=size, signed=FALSE, idxs=idxs) stopifnot(identical(x, data[idxs])) print(x)
[1] 6 22 38 54 70 86 102 118 134 150 166 182 198 214 230 246
cat("Read file...done\n")
Read file...done
cat("Write file...\n")
Write file...
# Update every 16:th byte in the file idxs <- seq(from=1, to=255, by=16) x0 <- data[idxs] writeBinFragments(pathname, idxs=idxs, rev(x0), size=size) x <- readBinFragments(pathname, what="integer", size=size, signed=FALSE, idxs=idxs) print(x)
[1] 241 225 209 193 177 161 145 129 113 97 81 65 49 33 17 1
stopifnot(identical(rev(x0), x)) # Update every 16:th byte in the file idxs <- seq(from=1, to=255, by=16) writeBinFragments(pathname, idxs=idxs, rev(x), size=size) x <- readBinFragments(pathname, what="integer", size=size, signed=FALSE, idxs=idxs) print(x)
[1] 1 17 33 49 65 81 97 113 129 145 161 177 193 209 225 241
stopifnot(identical(x0, x)) # Assert everything is as expected # Read the complete file x <- readBin(pathname, what="integer", size=size, signed=FALSE, n=length(data)) stopifnot(identical(x, data)) cat("Write file...done\n")
Write file...done
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - # Ditto but via a connection # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - cat("Read connection...\n")
Read connection...
# Read every 16:th byte in a connection con <- file(pathname, open="rb") idxs <- seq(from=1, to=255, by=16) x <- readBinFragments(con, what="integer", size=size, signed=FALSE, idxs=idxs) stopifnot(identical(x, data[idxs])) print(x)
[1] 1 17 33 49 65 81 97 113 129 145 161 177 193 209 225 241
# Read every 16:th byte in a connection starting with the 6th. idxs <- idxs + 5L x <- readBinFragments(con, what="integer", size=size, signed=FALSE, idxs=idxs, origin="start") stopifnot(identical(x, data[idxs])) print(x)
[1] 6 22 38 54 70 86 102 118 134 150 166 182 198 214 230 246
close(con) cat("Read connection...done\n")
Read connection...done
# Update every 16:th byte in a connection cat("Write connection...\n")
Write connection...
con <- file(pathname, open="r+b") idxs <- seq(from=1, to=255, by=16) x0 <- data[idxs] writeBinFragments(pathname, idxs=idxs, rev(x0), size=size) x <- readBinFragments(pathname, what="integer", size=size, signed=FALSE, idxs=idxs) print(x)
[1] 241 225 209 193 177 161 145 129 113 97 81 65 49 33 17 1
stopifnot(identical(rev(x0), x)) # Update every 16:th byte in the file idxs <- seq(from=1, to=255, by=16) writeBinFragments(pathname, idxs=idxs, rev(x), size=size) x <- readBinFragments(pathname, what="integer", size=size, signed=FALSE, idxs=idxs, origin="start") print(x)
[1] 1 17 33 49 65 81 97 113 129 145 161 177 193 209 225 241
stopifnot(identical(x0, x)) close(con) # Assert everything is as expected # Read the complete file x <- readBin(pathname, what="integer", size=size, signed=FALSE, n=length(data)) stopifnot(identical(x, data)) cat("Write connection...done\n")
Write connection...done
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - # Clean up # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - file.remove(pathname)
[1] TRUE