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1 library("MatrixEQTL");
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2
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3 # Number of columns (samples)
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4 n = 25;
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5
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6 # Number of covariates
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7 nc = 10;
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8
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9 # Generate the standard deviation of the noise
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10 noise.std = 0.1 + rnorm(n)^2;
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11
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12 # Generate the covariates
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13 cvrt.mat = 2 + matrix(rnorm(n*nc), ncol = nc);
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14
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15 # Generate the vectors with single genotype and expression variables
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16 snps.mat = cvrt.mat %*% rnorm(nc) + rnorm(n);
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17 gene.mat = cvrt.mat %*% rnorm(nc) + rnorm(n) * noise.std +
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18 1 + 0.5 * snps.mat + snps.mat * cvrt.mat[,nc];
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19 # Create 3 SlicedData objects for the analysis
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20 snps1 = SlicedData$new( matrix( snps.mat, nrow = 1 ) );
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21 gene1 = SlicedData$new( matrix( gene.mat, nrow = 1 ) );
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22 cvrt1 = SlicedData$new( t(cvrt.mat) );
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23
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24 # Produce no output files
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25 filename = NULL; # tempfile()
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26
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27 # Call the main analysis function
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28 me = Matrix_eQTL_main(
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29 snps = snps1,
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30 gene = gene1,
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31 cvrt = cvrt1,
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32 output_file_name = filename,
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33 pvOutputThreshold = 1,
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34 useModel = modelLINEAR_CROSS,
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35 errorCovariance = diag(noise.std^2),
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36 verbose = TRUE,
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37 pvalue.hist = FALSE );
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38
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39 # Pull Matrix eQTL results - t-statistic and p-value
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40 beta = me$all$eqtls$beta;
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41 tstat = me$all$eqtls$statistic;
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42 pvalue = me$all$eqtls$pvalue;
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43 rez = c(beta = beta, tstat = tstat, pvalue = pvalue);
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44 # And compare to those from the linear regression in R
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45 {
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46 cat("\n\n Matrix eQTL: \n");
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47 print(rez);
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48 cat("\n R summary(lm()) output: \n");
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49 lmdl = lm( gene.mat ~ snps.mat + cvrt.mat + snps.mat*cvrt.mat[,nc],
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50 weights = 1/noise.std^2 );
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51 lmout = tail(summary(lmdl)$coefficients,1)[,c(1,3,4)];
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52 print( tail(lmout) );
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53 }
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54
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55 # Results from Matrix eQTL and "lm" must agree
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56 stopifnot(all.equal(lmout, rez, check.attributes=FALSE));
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