我的数据是由V6的ID分组而成的群中的每个元素的“指数”,并下令位置(V1:V3):创建用于data.table
dt
V1 V2 V3 V4 V5 V6
1: chr1 3054233 3054733 . + ENSMUSG00000090025
2: chr1 3102016 3102125 . + ENSMUSG00000064842
3: chr1 3205901 3207317 . - ENSMUSG00000051951
4: chr1 3206523 3207317 . - ENSMUSG00000051951
5: chr1 3213439 3215632 . - ENSMUSG00000051951
6: chr1 3213609 3216344 . - ENSMUSG00000051951
7: chr1 3214482 3216968 . - ENSMUSG00000051951
8: chr1 3421702 3421901 . - ENSMUSG00000051951
9: chr1 3466587 3466687 . + ENSMUSG00000089699
10: chr1 3513405 3513553 . + ENSMUSG00000089699
我想这样做是按位置添加一个带有索引的额外列,也就是说,V6中的每个组的第一个元素是“1”,第二个元素是“2”,依此类推。我能做到这一点使用ddply和一个自定义功能:
rankExons <- function(x){
if(unique(x$V5) == "+"){
x$index <- seq_len(nrow(x))}
else{
x$index <- rev(seq_len(nrow(x)))}
x
}
indexed <- ddply(dt, .(V6), rankExons)
indexed
V1 V2 V3 V4 V5 V6 index
1 chr1 3205901 3207317 . - ENSMUSG00000051951 6
2 chr1 3206523 3207317 . - ENSMUSG00000051951 5
3 chr1 3213439 3215632 . - ENSMUSG00000051951 4
4 chr1 3213609 3216344 . - ENSMUSG00000051951 3
5 chr1 3214482 3216968 . - ENSMUSG00000051951 2
6 chr1 3421702 3421901 . - ENSMUSG00000051951 1
7 chr1 3102016 3102125 . + ENSMUSG00000064842 1
8 chr1 3466587 3466687 . + ENSMUSG00000089699 1
9 chr1 3513405 3513553 . + ENSMUSG00000089699 2
10 chr1 3054233 3054733 . + ENSMUSG00000090025 1
不幸的是,它是完整的数据集(〜620K行)非常缓慢,当使用平行崩溃和烧伤:
library(doMC)
registerDoMC(cores=6)
indexed <- ddply(dt, .(V6), rankExons, .parallel=TRUE)
Error: serialization is too large to store in a raw vector
Error: serialization is too large to store in a raw vector
Error: serialization is too large to store in a raw vector
Error: serialization is too large to store in a raw vector
Error: serialization is too large to store in a raw vector
Error: serialization is too large to store in a raw vector
Warning message:
In mclapply(argsList, FUN, mc.preschedule = preschedule, mc.set.seed = set.seed, :
all scheduled cores encountered errors in user code
所以,我去了data.table,但无法得到它的工作。这是我试过的:
setkey(dt, "V6")
dt[,index:=rankExons(dt), by=V6]
dt[,rankExons(.sd), by=V6, .SDcols=c("V5, V6")]
而且都失败了。我如何用data.table重新创建我的ddply?
dput(dt)
structure(list(V1 = c("chr1", "chr1", "chr1", "chr1", "chr1",
"chr1", "chr1", "chr1", "chr1", "chr1"), V2 = c(3054233L, 3102016L,
3205901L, 3206523L, 3213439L, 3213609L, 3214482L, 3421702L, 3466587L,
3513405L), V3 = c(3054733L, 3102125L, 3207317L, 3207317L, 3215632L,
3216344L, 3216968L, 3421901L, 3466687L, 3513553L), V4 = c(".",
".", ".", ".", ".", ".", ".", ".", ".", "."), V5 = c("+", "+",
"-", "-", "-", "-", "-", "-", "+", "+"), V6 = c("ENSMUSG00000090025",
"ENSMUSG00000064842", "ENSMUSG00000051951", "ENSMUSG00000051951",
"ENSMUSG00000051951", "ENSMUSG00000051951", "ENSMUSG00000051951",
"ENSMUSG00000051951", "ENSMUSG00000089699", "ENSMUSG00000089699"
)), .Names = c("V1", "V2", "V3", "V4", "V5", "V6"), class = c("data.table",
"data.frame"), row.names = c(NA, -10L), .internal.selfref = <pointer: 0x1de6a88>)
+1非常很好的框架问题。 – Arun
“提出好问题,获得好答案”应该是stackoverflow的座右铭:) – fridaymeetssunday