更改最大差值以结转值的次数 [英] Change maxgap for number of times a value is carried forward
问题描述
我有一个类似于以下内容的数据框:
I have a data frame similar to the following:
library(data.table)
test <- data.table(data.frame("value" = c(5,NA,8,NA,NA,8,6,NA,NA,10),
"locf_N" = c(1,NA,1,NA,NA,1,2,NA,NA,2)) )
在此数据帧中,我有一个变量,该变量指示我可以进行最后一次观察的时间(locf_N).这不是所有观察值的固定数字.我试图为此目的在na.locf函数中使用maxgap参数,但这实际上并不是我想要的.
In this data frame I have a variable that indicates the times I could carry forward the last observation (locf_N). This is not a fixed number for all observations. I have tried to use the maxgap parameter in the na.locf function for this purpose but it is not actually what I am looking for.
require(zoo)
test[,value := na.locf(value, na.rm = FALSE, maxgap = 1)]
test[,value := na.locf(value, na.rm = FALSE, maxgap = locf_N)]
是否有任何参数设置可以延续上一次观察的次数?任何想法都欢迎.
Is there any parameter to set the number of times the last observation can be carried forward? Any ideas welcome.
所需的输出:
output <- data.table(data.frame("value" = c(5,5,8,8,NA,8,6,6,6,10),
"locf_N" = c(1,NA,1,NA,NA,1,2,NA,NA,2)) )
推荐答案
cumsum(!is.na(value))
是一个分组向量,用于将每个非NA与以下NA进行分组.然后,对于每个这样的组,将第一个值重复所需的次数,并将其余值保留为NA.
cumsum(!is.na(value))
is a grouping vector that groups each non-NA with the following NAs. Then for each such group repeat the first value the required number of times and leave the remaining values as NA.
test[, list(value = replace(value, 1:min(.N, locf_N[1] + 1), value[1]), locf_N),
by = cumsum(!is.na(value))][, -1]
给予:
value locf_N
1: 5 1
2: 5 NA
3: 8 1
4: 8 NA
5: NA NA
6: 8 1
7: 6 2
8: 6 NA
9: 6 NA
10: 10 2
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