Added function to read Perkin-Elmer spectra files.

This function reads *.SP files (ASCII), and currently fetches only data (no meta-data).

PELambda/SP2df.R

@@ -0,0 +1,49 @@
+##################################################
+#################### SP2df #######################
+##################################################
+SP2df <- function(datafile) {
+   ## Description:
+   ##   For now just extracting the bare minimum (the data itself) from SP (ASCII) spectra files.
+   ## Usage:
+   ##   SP2df(datafile)
+   ## Arguments:
+   ##   datafile: text string with full path to TXT file
+   ##             containing single or multiple data ranges
+   ## Value:
+   ##   Dataframe with the following columns:
+   ##   $ sampleid        : chr
+   ##   $ wavelength      : num
+   ##   $ intensity       : num
+   #
+   range.data.start.rexp <- "\\#DATA"
+   #range.data.end.rexp <- ">+End[\\s\\w]*<+"
+   
+   # Read the input file
+   dfile <- file(datafile, "r")
+   # Note that readLines apparently completely skips empty lines. 
+   # That causes line numbers to not match between source and f vector.
+   f <- readLines(dfile, n=-1) # read _all_ lines from data file
+   close(dfile)
+   
+   # Create a sampleid for the current job (use the folder name)
+   sampleid <- basename(dirname(datafile))
+   
+   # Look for data start marker line
+   range.data.start.row <- grep(range.data.start.rexp, f, perl = TRUE) + 1
+   # Data ends one line before EOF
+   range.data.end.row <- length(f) - 1
+   
+   # Extract data (as-is)
+   data.raw <- f[range.data.start.row:range.data.end.row]
+
+   
+   # Collect data into dataframe
+   zz <- textConnection(data.raw, "r")
+   data <- data.frame(stringsAsFactors = FALSE,
+                      sampleid,
+                      matrix(scan(zz, what = numeric()), ncol = 2, byrow = T))
+   close(zz)
+   names(data) <- c("sampleid", "wavelength", "intensity")
+                                                                   
+   return(data)
+}