R:有条件地替换循环中的值 [英] R: conditionally replace values in loop

问题描述

我有一个像这样的数据框:

I have a dataframe like so:

rel      <- c(2, 5, NA, 3, 6)
year.in  <- c(4, NA, 2, 3, 2)
year.out <- c(6, 7, NA, 5, 4)
year.1   <- c(NA, NA, NA, NA, NA)
year.2   <- c(NA, NA, NA, NA, NA)
year.3   <- c(NA, NA, NA, NA, NA)
year.4   <- c(NA, NA, NA, NA, NA)
year.5   <- c(NA, NA, NA, NA, NA) 

df <- as.data.frame(cbind(rel, year.in, year.out, year.1, year.2, year.3, 
                      year.4, year.5))

我想做的是将year.1-year.5中的缺失值更新为'rel'，但前提是:(year.in> = year.i AND year.out&=; year.i)(其中i为1:5)

What I would like to do is update the missing values in year.1 - year.5 with the value of 'rel', but only if: (year.in >= year.i AND year.out <= year.i) (with i is 1:5)

着眼于刚入学的那一年，我想到了:

Focussing on the just the year of entry, I came up with this:

for (i in 1:5) ifelse(df$year.in < i,
    df[paste("year", i, sep= ".")]<- NA,
    df[paste("year", i, sep= ".")]<- df["rel"])

但这只是用rel的值替换了所有year.i变量.

But this merely replaces all year.i variables with the value of rel.

我有两个问题:

• 如何在提到的条件下使用"rel"值更新year.i变量?

• how can I update the year.i variables with the 'rel' values on the conditions mentioned?

在这里使用if else语句是否不好?

is it bad to use the if else statement here?

最好先谢谢，

理查德

推荐答案

library(data.table)
dt = data.table(df)

for(i in 1:5) dt[year.in <= i & i <= year.out, paste0('year.', i) := rel]

dt
#   rel year.in year.out year.1 year.2 year.3 year.4 year.5
#1:   2       4        6     NA     NA     NA      2      2
#2:   5      NA        7     NA     NA     NA     NA     NA
#3:  NA       2       NA     NA     NA     NA     NA     NA
#4:   3       3        5     NA     NA      3      3      3
#5:   6       2        4     NA      6      6      6     NA

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