VCF to PED

One of the classic bioinformatics problems is converting files from one format into another. In this post, I go through the process of creating a PED and MAP file from a VCF file. All the files described in this post are available in this GitHub repository.

Continue Reading

BED to GRanges

Updated 2015 April 6th to include the intersect_bed() function in the bedr package. Last year I saw a post on Writing an R package from scratch and I always wanted to follow the tutorial. Yesterday while trying to make some plots using Gviz, I had some BED-like files (not supported by Gviz), which I wanted...

Continue Reading

BAM to CRAM

I was catching up on some blog reading and just read Ewan's latest post on CRAM going mainline. CRAM files are alignment files like BAM files but provides better compression. The toolkit for manipulating CRAM files is called CRAMTools and is a set of Java tools and APIs for efficient compression of sequence read data....

Continue Reading

Getting started with Picard

Updated hyperlinks on the 2015 January 26th; please comment if you find any more dead links. Picard is a suite of Java-based command-line utilities that manipulate SAM/BAM files. Currently, I'm analysing some paired-end libraries and I wanted to calculate the average insert size based on the alignments; that's how I found Picard. While reading the...

Continue Reading

I've joined Twitter

Today while reading a paper, I found some interesting one-liner facts. They are way too short to create a post on but I would like to make a repository of them. What better place to store these facts than Twitter! You can follow me on Twitter for a list of facts on molecular biology and...

Continue Reading

Setting up Windows for bioinformatics

Updated 2014 May 20th: I created this post on the 19th of August in 2011 when I just purchased yet another computer (Core i7 2600, 8 gigs ram and a GTX460) and was setting it up for doing some bioinformatics. I updated this page again around mid 2013 when I bought another laptop (Asus N56V,...

Continue Reading

DESeq vs. edgeR vs. baySeq

6th April 2012: For a more updated version of this post, please refer see this post. A very simple comparison Using the TagSeqExample.tab file from the DESeq package as the benchmark dataset. According to DESeq authors, T1a and T1b are similar, so I removed the second column in the file corresponding to T1a: Hierarchical clustering...

Continue Reading