[R] Reshaping an array - how does it work in R

Roy Mendelssohn - NOAA Federal roy.mendelssohn at noaa.gov
Fri Mar 18 22:28:35 CET 2016

Hi All:

I am working with a very large array.  if noLat is the number of latitudes, noLon the number of longitudes and noTime the number of  time periods, the array is of the form:

myData[noLat, no Lon, noTime].

It is read in this way because that is how it is stored in a (series) of netcdf files.  For the analysis I need to do, I need instead the array:

myData[noLat*noLon, noTime].  Normally this would be easy:

myData<- array(myData,dim=c(noLat*noLon,noTime))

My question is how does this command work in R - does it make a copy of the existing array, with different indices for the dimensions, or does it just redo the indices and leave the given array as is?  The reason for this question is my array is 30GB in memory, and I don’t have enough space to have a copy of the array in memory.  If the latter I will have to figure out a work around to bring in only part of the data at a time and put it into the proper locations.



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Roy Mendelssohn
Supervisory Operations Research Analyst
Environmental Research Division
Southwest Fisheries Science Center
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