附图(曼哈顿图)包含来自基因组和X轴的染色体位置-log(p),其中p是与点(变体)相关的p值,从那个特定的位置。 曼哈顿图中的峰检测
我已经使用下述R代码来生成它(从间隙包):
require(gap)
affy <-c(40220, 41400, 33801, 32334, 32056, 31470, 25835, 27457, 22864, 28501, 26273,
24954, 19188, 15721, 14356, 15309, 11281, 14881, 6399, 12400, 7125, 6207)
CM <- cumsum(affy)
n.markers <- sum(affy)
n.chr <- length(affy)
test <- data.frame(chr=rep(1:n.chr,affy),pos=1:n.markers,p=runif(n.markers))
oldpar <- par()
par(cex=0.6)
colors <- c("red","blue","green","cyan","yellow","gray","magenta","red","blue","green", "cyan","yellow","gray","magenta","red","blue","green","cyan","yellow","gray","magenta","red")
mhtplot(test,control=mht.control(colors=colors),pch=19,bg=colors)
> head(test)
chr pos p
1 1 1 0.79296584
2 1 2 0.96675136
3 1 3 0.43870076
4 1 4 0.79825513
5 1 5 0.87554143
6 1 6 0.01207523
我对获得高于某一阈值的曲线的峰的坐标(-log (p))。
你是什么意思的“过零”? – 2013-02-25 13:57:41
“峰值的一阶导数在峰值最大处有一个向下的过零点” - 从这里开始:http://terpconnect.umd.edu/~toh/spectrum/PeakFindingandMeasurement.htm#findpeaks;我不确定我的理解是否正确 – agatha 2013-02-25 14:03:26
@agatha,这与您在[** biostars **](http://www.biostars.org/p/64416/#64558)上询问的问题有何不同提供了一个答案..? – Arun 2013-02-25 14:34:22