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coala (version 0.2.0)

sumstat_omega: Calculates the Omega Statistic from Simulations

Description

This summary statistic calculates the omega statistic introduced by Kim & Nielsen (2004) from the simulated data. The statistic is senistive for LD patterns that are characteristic for selective sweeps. To calculate the statistic, coala relies on the command line program http://sco.h-its.org/exelixis/web/software/omegaplus/index.html{OmegaPlus}, which needs to be downloaded and compiled manually in order to use the statistic.

Usage

sumstat_omega(name = "omega", min_win = 100, max_win = 1000,
  grid = 1000, binary = "automatic", transformation = identity)

Arguments

name
The name of the summary statistic. When simulating a model, the value of the statistics are written to an entry of the returned list with this name. Summary statistic names must be unique in a model.
min_win
The minimum distance from the grid point that a SNP must have to be included in the calculation of omega.
max_win
The maximum distance from the grid point that a SNP must have to be included in the calculation of omega.
grid
The number of points for which omega is calculated on each locus. Should be significantly lower than the locus length.
binary
The path of the binary for OmegaPlus. If set to "automatic", coala will try to find a binary called "OmegaPlus" using the PATH environment variable.
transformation
An optional function for transforming the results of the statistic. If specified, the results of the transformation are returned instead of the original values.

Value

  • A data frame consisting of the locus and the genetic position of the calculated omega values.

References

Linkage disequilibrium as a signature of selective sweeps. Y. Kim and R. Nielsen (2004). Genetics, 167, 1513-1524.

OmegaPlus: a scalable tool for rapid detection of selective sweeps in whole-genome datasets. N. Alachiotis, A. Stamatakis and P. Pavlidis (2012). Bioinformatics Vol. 28 no. 17 2012, pages 2274-2275 doi:10.1093/bioinformatics/bts419