@@ -374,17 +374,26 @@ readCelUnits <- function(filenames, units=NULL, stratifyBy=c("nothing", "pmmm",

   fields <- vector("list", length(cellValueFields));

   names(fields) <- cellValueFields;

+  # Keep a copy for groups with empty fields

+  emptyFields <- fields;

+

   # Add a dimension for the arrays, unless only one array is read

   # and the array dimension is not wanted.

   addArrayDim <- (nbrOfArrays >= 2 || !dropArrayDim);

   seqOfArrays <- list(1:nbrOfArrays);

   offset <- 0;

+  

   res <- lapply(cdf, FUN=function(u) {

-    lapply(u$groups, FUN=function(g) {

+    lapply(.subset2(u, "groups"), FUN=function(g) {

       # Same dimensions of all fields

       field <- .subset2(g, 1);  # Faster than g[[1]]

       ncells <- length(field);

+

+      # Empty unit group?

+      if (ncells == 0)

+        return(fields <- emptyFields);

+

       idxs <- offset + 1:ncells;

       offset <<- offset + ncells;

@@ -445,6 +454,9 @@ readCelUnits <- function(filenames, units=NULL, stratifyBy=c("nothing", "pmmm",

 ############################################################################

 # HISTORY:

+# 2007-02-01 [KS]

+# o Now readCelUnits() can handle unit groups for which there are no probes,

+#   e.g. when stratifying on PM in a unit containing only MMs.

 # 2006-10-04 [HB]

 # o Made readCelUnits() a bit more clever if a 'cdf' structure with only

 #   cell indices is passed. Then all fields are just indices and one can

@@ -2,6 +2,9 @@ Package: affxparser

 ===================

 Version: 1.7.3 [2007-02-01]

+o Now readCelUnits() can handle unit groups for which there are 

+  no probes, e.g. when stratifying on PM in a unit containing 

+  only MMs. 

 o Added writeCdfHeader(), writeCdfQcUnits() and writeCdfUnits(). 

   These are all used by writeCdf(). They also make it possible

   to write a CDF in chunks in order to for instance convertCdf()