我有一个data.table
,我想为其添加一列随机二项式数字作为试验次数,并基于其他列添加多个概率:
require(data.table)
DT = data.table(
ID = letters[sample.int(26,10, replace = T)],
Quantity=as.integer(100*runif(10))
)
prob.vecs <- LETTERS[1:5]
DT[,(prob.vecs):=0]
set.seed(123)
DT[,(prob.vecs):=lapply(.SD, function(x){runif(.N,0,0.2)}), .SDcols=prob.vecs]
DT
ID Quantity A B C D E
1: b 66 0.05751550 0.191366669 0.17790786 0.192604847 0.02856000
2: l 9 0.15766103 0.090666831 0.13856068 0.180459809 0.08290927
3: u 38 0.08179538 0.135514127 0.12810136 0.138141056 0.08274487
4: d 27 0.17660348 0.114526680 0.19885396 0.159093484 0.07376909
5: o 81 0.18809346 0.020584937 0.13114116 0.004922737 0.03048895
6: f 44 0.00911130 0.179964994 0.14170609 0.095559194 0.02776121
7: d 81 0.10562110 0.049217547 0.10881320 0.151691908 0.04660682
8: t 81 0.17848381 0.008411907 0.11882840 0.043281587 0.09319249
9: x 79 0.11028700 0.065584144 0.05783195 0.063636202 0.05319453
10: j 43 0.09132295 0.190900730 0.02942273 0.046325157 0.17156554
现在我要添加五列Quantity_A
Quantity_B
Quantity_C
Quantity_D
Quantity_E
,其将rbinom
与第二列中的相应概率和数量一起应用。
例如,Quantity_A的第一个条目为:
set.seed(741)
sum(rbinom(66,1,0.05751550))
> 2
这个问题似乎与以下帖子非常相似:How do I pass column-specific arguments to lapply in data.table .SD?,但我似乎无法使其正常工作。我的尝试:
DT[,(paste0("Quantity_", prob.vecs)):= mapply(function(x, Quantity){sum(rbinom(Quantity, 1 , x))}, .SD), .SDcols = prob.vecs]
rbinom(Quantity,1,x)中的错误: 参数“数量”缺失,没有默认值
有什么想法吗?
答案 0 :(得分:1)
我似乎找到了一种解决方法,尽管我不太确定为什么这样做(可能与功能rbinom
不在两个参数中都进行向量化有关):
首先定义一个索引:
DT[,Index:=.I]
,然后按索引进行操作:
DT[,(paste0("Quantity_", prob.vecs)):= lapply(.SD,function(x){sum(rbinom(Quantity, 1 , x))}), .SDcols = prob.vecs, by=Index]
set.seed(789)
ID Quantity A B C D E Index Quantity_A Quantity_B Quantity_C Quantity_D Quantity_E
1: c 37 0.05751550 0.191366669 0.17790786 0.192604847 0.02856000 1 0 4 7 8 0
2: c 51 0.15766103 0.090666831 0.13856068 0.180459809 0.08290927 2 3 5 9 19 3
3: r 7 0.08179538 0.135514127 0.12810136 0.138141056 0.08274487 3 0 0 2 2 0
4: v 53 0.17660348 0.114526680 0.19885396 0.159093484 0.07376909 4 8 4 16 12 3
5: d 96 0.18809346 0.020584937 0.13114116 0.004922737 0.03048895 5 17 3 12 0 4
6: u 52 0.00911130 0.179964994 0.14170609 0.095559194 0.02776121 6 1 3 8 6 0
7: m 43 0.10562110 0.049217547 0.10881320 0.151691908 0.04660682 7 6 1 7 6 2
8: z 3 0.17848381 0.008411907 0.11882840 0.043281587 0.09319249 8 1 0 2 1 1
9: m 3 0.11028700 0.065584144 0.05783195 0.063636202 0.05319453 9 1 0 0 0 0
10: o 4 0.09132295 0.190900730 0.02942273 0.046325157 0.17156554 10 0 0 0 0 0
数字看起来很适合我
如果有人找到了没有索引的解决方案,我们将不胜感激。