Extract the Print Layout of an Array from the GAL File
From the Block, Row and Column information in a genelist, determine the number of grid rows and columns on the array and the number of spot rows and columns within each grid.
getLayout(gal, guessdups=FALSE) getLayout2(galfile) getDupSpacing(ID)
gal |
data.frame containing the GAL, i.e., giving the position and gene identifier of each spot |
galfile |
name or path of GAL file |
guessdups |
logical, if |
ID |
vector or factor of gene IDs |
A GenePix Array List (GAL) file is a list of genes and associated information produced by an Axon microarray scanner.
The function getLayout
determines the print layout from a data frame created from a GAL file or gene list.
The data.frame must contain columns Block
, Column
and Row
.
(The number of tip columns is assumed to be either one or four.)
On some arrays, each probe may be duplicated a number of times (ndups
) at regular intervals (spacing
) in the GAL file.
getDupSpacing
determines valid values for ndups
and spacing
from a vector of IDs.
If guessdups=TRUE
, then getLayout
calls getDupSpacing
.
The function getLayout2
attempts to determine the print layout from the header information of an actual GAL file.
A printlayout
object, which is a list with the following components.
The last two components are present only if guessdups=TRUE
.
ngrid.r |
integer, number of grid rows on the arrays |
ngrid.c |
integer, number of grid columns on the arrays |
nspot.r |
integer, number of rows of spots in each grid |
nspot.c |
integer, number of columns of spots in each grid |
ndups |
integer, number of times each probe is printed on the array |
spacing |
integer, spacing between multiple printings of each probe |
Gordon Smyth and James Wettenhall
An overview of LIMMA functions for reading data is given in 03.ReadingData.
# gal <- readGAL() # layout <- getLayout(gal)
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