This function executes a ubuntu docker that subset a matrix
subSetCell( group = c("sudo", "docker"), scratch.folder, file, separator, cells.number )
a character string. Two options: sudo or docker, depending to which group the user belongs
a character string indicating the path of the scratch folder
a character string indicating the path of the file, with file name and extension included
separator used in count file, e.g. '\t', ','
number of cells to be extracted
Luca Alessandri, alessandri [dot] luca1991 [at] gmail [dot] com, University of Torino