library(knitr) opts_chunk$set(out.extra='style="display:block; margin: auto"', fig.align="center")
snp.plotter is an R package that creates publishable-quality plots of p-values using single SNP and/or haplotype data. Main features of the package include options to display a linkage disequilibrium (LD) plot and the ability to plot multiple sets of results simultaneously. Plots can be created using global and/or individual haplotype p-values along with single SNP p-values. Images are created as either Portable Document Format (PDF) or Encapsulated (EPS) files.
Here is a sample image as both a PDF and a EPS image. PDF images can be viewed using the free Adobe Reader software. EPS (or PDF) images can be viewed using front-end software for Ghostscript, a Postscript and PDF interpreter: Ghostview and GV for Unix/X11 systems and GSView for Windows.
Researchers conducting gene association studies who need to create images showing results in the form of p-values of their work along with a linkage disequilibrium plot to show the underlying structure of the study population. Because snp.plotter is a visualization tool, the type of study design used either family-based, case-control, or a combination is irrelevant.
snp.plotter requires the installation of R, the statistical computing software, freely available here for Linux, Windows, or MacOS. snp.plotter uses three contributed packages: grid, lattice, and genetics available from the R Project website. snp.plotter can be downloaded CRAN. Packages in the current working directory of R can be installed using the install.packages command.
In Windows, make sure that you have downloaded the .zip version of a package, which is a pre-compiled binary. Change the word PACKAGE_FILENAME to the name of the package being installed.
install.packages("PACKAGE_FILENAME.zip", repos=NULL)
In Unix/Linux, make sure that you have downloaded a source package, the .tar.gz version, of a package. Change the word PACKAGE_FILENAME to the name of the package being installed.
install.packages("PACKAGE_FILENAME.tar.gz", repos=NULL)
The following error indicates that additional packages need to be installed: PACKAGE_FILENAME can be grid or genetics. These packages can be downloaded from CRAN. and installed using the same process described above.
Error: package 'PACKAGE_FILENAME' could not be loaded
Once snp.plotter and its dependencies are installed, snp.plotter can be loaded into R using this command:
library(snp.plotter)
snp.plotter is then run using the following command. Explanation of snp.plotter configuration files and input files is provided in the file formats section. The configuration file specifies all the characteristics for the plot to be produced and the names of the data files to be used as input. Example configuration and input files are also provided.
snp.plotter(config.file="config.txt")
Information about the configuration options is provided in the documentation on CRAN, which can viewed from within R using this command.
?snp.plotter
The listing below shows the most common scenarios for inclusion of a figure into a publication; methods will vary based on the intended publication type:
\documentclass{article} \usepackage{graphicx} \begin{document} \begin{figure} \includegraphics{FILENAME} \end{figure} \end{document}
gs -q -dNOPAUSE -dSAFER -dBATCH -r300 -g1050x1050 -sOutputFile=FILENAME.jpg -sDEVICE=jpeg FILENAME.eps
snp.plotter uses tab-delimited text files as input files. These files can be created in a basic text editor such as Notepad in Windows or Excel saved as tab-delimited files using the "Save As" option. A dataset is composed a configuration file, a SNP and haplotype file for each result set, one genotype file, and an optional palette file. More information about these files can be found in the documentation on CRAN.
SNP.FILE=snp8_ss.txt,snp8_ss2.txt HAP.FILE=snp8_haplo.txt,snp8_haplo2.txt PALETTE.FILE=palette.txt EVEN.SPACED=TRUE USE.GBL.PVAL=TRUE DISP.HAP=TRUE DISP.LDMAP=FALSE LD.COLOR.SCHEME=heat COLOR.LIST=blue,red SYMBOLS=circle,NA PVAL.THRESHOLD=1 LAB.Y=ln GENOTYPE.FILE=snp8_geno.txt LD.TYPE=rsquare DISP.COLOR.BAR=TRUE DISP.TYPE=symbol DISP.LEGEND=TRUE SAMPLE.LABELS=Sample 1,Sample 2 IMAGE.TYPE=eps DISP.SNP=TRUE IMAGE.TITLE="8 SNP Example" IMAGE.NAME=snp8_example IMAGE.SIZE=3.5
ASSOC SNP.NAME LOC SS.PVAL + rs10_8 126272509 0.065 - rs11_8 126274467 0.029 + rs12_8 126275017 0.046 - rs13_8 126275750 0.005 + rs14_8 126283659 0.258 + rs15_8 126284467 0.036 - rs16_8 126298007 0.05 - rs17_8 126299520 0.202
ASSOC G.PVAL I.PVAL rs10_8 rs11_8 rs12_8 rs13_8 rs14_8 rs15_8 rs16_8 rs17_8 - 0.015 0.004 1 1 1 + 0.015 0.062 1 2 2 + 0.075 0.079 1 1 1 + 0.075 0.039 2 2 2 - 0.032 0.121 1 1 1 + 0.032 0.153 1 2 2 + 0.425 0.474 1 1 1 + 0.425 0.003 2 2 2 + 0.1 0.077 1 1 1 + 0.1 0.1 1 2 2 - 0.003 0.341 1 1 1 + 0.003 0.001 2 2 2
1 1 0 0 1 1 1 1 1 1 2 1 0 0 2 1 1 1 1 1 3 1 0 0 1 1 1 1 1 2 4 1 0 0 2 1 1 1 2 2 5 1 0 0 1 1 0 0 1 1
FFFFFF CCCCFF 9999FF 6666FF 3333FF 0000FF 0000CC 000099 000066
Anushka Aqil for her feedback
Please cite the following publication, if you include figures generated with snp.plotter
Luna A, Nicodemus KK. snp.plotter: an R-based SNP/haplotype association and linkage disequilibrium plotting package. Bioinformatics. 2007 Mar 15;23(6):774-6.
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