[英]Reshaping data table to make column names into row names
我在R
有一个data.table
> dt
SAMPLE junction count
1: R1 a 1
2: R2 a 1
3: R3 b 1
4: R3 a 1
5: R1 c 2
现在我想“重塑”数据表以形成data frame
m
(基本上通过样本矩阵连接,索引值为对应的计数值)。 另外,观察到对于dt
不存在的(SAMPLE,junction)
对,我假设相应的count
数值zero
。 有人可以帮助我如何实现这一目标吗?
> m
R1 R2 R3
a 1 1 1
b 0 0 1
c 2 0 0
dcast
的data.table
将数据集从“long”格式更改为“wide”格式。
library(data.table)#v1.9.5+
dcast(dt, junction~SAMPLE, value.var='count', fill=0)
# junction R1 R2 R3
#1: a 1 1 1
#2: b 0 0 1
#3: c 2 0 0
如果需要矩阵输出
library(reshape2)
acast(dt, junction~SAMPLE, value.var='count', fill=0)
# R1 R2 R3
#a 1 1 1
#b 0 0 1
#c 2 0 0
或者来自base R
xtabs
xtabs(count~junction+SAMPLE, dt)
使用tidyr
spread
的另一种方法:
library(tidyr)
spread(dt, SAMPLE, count, fill=0)
# junction R1 R2 R3
#1: a 1 1 1
#2: b 0 0 1
#3: c 2 0 0
或与老同学的解决方案reshape
从stats
:
reshape(dt, timevar='SAMPLE', idvar=c('junction'), direction='wide')
# junction count.R1 count.R2 count.R3
#1: a 1 1 1
#2: b NA NA 1
#3: c 2 NA NA
数据:
dt = structure(list(SAMPLE = c("R1", "R2", "R3", "R3", "R1"), junction = c("a",
"a", "b", "a", "c"), count = c(1, 1, 1, 1, 2)), .Names = c("SAMPLE",
"junction", "count"), row.names = c(NA, -5L), class = c("data.table",
"data.frame"), .internal.selfref = <pointer: 0x05e924a0>)
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