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spp (version 1.16.0)

get.binding.characteristics: Calculate characteristics of observed DNA-binding signal from cross-correlation profiles

Description

The methods calculates strand cross-correlation profile to determine binding peak separation distance and approximate window size that should be used for binding detection. If quality scores were given for the tags, which quality bins improve the cross-correlation pattern.

Usage

get.binding.characteristics(data, srange = c(50, 500), bin = 5, 
  cluster = NULL, debug = F, min.tag.count = 1000, 
  acceptance.z.score = 3, remove.tag.anomalies = T, 
  anomalies.z = 5,accept.all.tags=F)

Arguments

data

Tag/quality data: output of read.eland.tags or similar function

srange

A range within which the binding peak separation is expected to fall. Should be larger than probe size to avoid artifacts.

bin

Resolution (in basepairs) at which cross-corrrelation should be calculated. bin=1 is ideal, but takes longer to calculate.

cluster

optional snow cluster for parallel processing

debug

whether to print debug messages

min.tag.count

minimal number of tags on the chromosome to be considered in the cross-correlation calculations

acceptance.z.score

A Z-score used to determine if a given tag quality bin provides significant improvement to the strand cross-correlation

remove.tag.anomalies

Whether to remove singular tag count peaks prior to calculation. This is recommended, since such positions may distort the cross-correlation profile and increase the necessary computational time.

anomalies.z

Z-score for determining if the number of tags at a given position is significantly higher about background, and should be considered an anomaly.

accept.all.tags

Whether tag alignment quality calculations should be skipped and all available tags should be accepted in the downstream analysis.

Value

cross.correlation

Cross-correlation profile as an $x/$y data.frame

peak

Position ($x) and height ($y) of automatically detected cross-correlation peak.

whs

Optimized window half-size for binding detection (based on the width of the cross-correlation peak)

quality.bin.acceptance

A list structure, describing the effect of inclusion of different tag quality bins on cross-correlation, and a resolution on which bins should be considered.

informative.bins: A boolean vector indicating whether the inclusion of tags from the tag quality bin specified in the name attribute signiificantly increases cross-correlation profile near the peak. quality.cc: A list giving the cross-correlation profile after the inclusion of the tags from different quality bins