I am trying to perform differential gene expression of microarray data using limma. I am referring to the R script in GEO2R. Can someone explain me these steps of log2 transformation. I am a little confused regarding the same. Thankyou so much

Here is the log2 trasnformation code

log2 transformation

ex <- exprs(gset) qx <- as.numeric(quantile(ex, c(0., 0.25, 0.5, 0.75, 0.99, 1.0), na.rm=T))

LogC <- (qx[5] > 100) || (qx[6]-qx[1] > 50 && qx[2] > 0) if (LogC ) { ex[which(ex <= 0)] <- NaN exprs(gset) <- log2(ex) }