Salmon Beta v0.2.2

What is Salmon?

It's a type of fish! But, in the context of RNA-seq, it's the
successor to Sailfish (a rapid "alignment-free" method for transcript
quantification from RNA-seq reads).

Why use Salmon?

Well, Salmon is designed with a lot of what we learned from Sailfish
in mind. We're still adding to and improving Salmon, but it already
has a number of benefits over Sailfish; for example:

• Salmon can make better use of paired-end information than Sailfish. The
  algorithm used in Salmon considers both ends of a paired-end read
  simultaneously, rather than independently as does Sailfish. Therefore it is
  able to make use of any increased specificity that results from this
  information.
• Salmon has a smaller memory footprint that Sailfish. While the
  quantification phase of Sailfish already has a fairly compact memory
  footprint, Salmon's is even smaller. Additionally, building the Salmon index
  (which is only required if you don't use the alignment-based mode) requires
  substantially less memory, and can be faster, than building the Sailfish
  index.
• Salmon can use (but doesn't require) pre-computed alignments. If you want,
  you can use Salmon much like Sailfish, by building an index and feeding it
  raw reads. However, if you already have reads from your favorite, super-fast
  aligner (cough cough maybe STAR), you can use them with Salmon to quantify
  the transcript abundances.
• Salmon is fast --- in all of our testing so far, it's actually faster than
  Sailfish (though the same relationship doesn't hold between the actual fish).

Further details are contained in the online documentation.

What's New

Version 0.2.2 includes a number of improvements and bug fixes, including a new logger and fewer dependencies. The other big addition is the implementation of a "mapping cache" in read-based quantification mode (this is described in the documentation). This should substantially speed up salmon for smaller experiments.