Question

有一个数据框，其中包含日期的三个度量（即date1，date2，date3）以及标记为“ s1”和“ s2”的其他度量。我正在尝试根据这些日期以及度量“ s1”和“ s2”创建标记为“ x1”和“ x2”的新列。例如，如果date1小于或等于date2，则列“ x1”应取值为3，否则应保留s1的值。同样，如果date1小于或等于date3，则“ x2”列应取值为3，否则应保留s2的值。下面是数据的一部分

df <-
structure(
list(
  id = c(1L, 2L, 3L, 4L,5L),
  date1 = c("1/4/2004", "3/8/2004", "NA", "13/10/2004","11/3/2003"),
  date2 = c("8/6/2002", "11/5/2004", "3/5/2004", 
"25/11/2004","21/1/2004"),
  s1=c(1,2,1,"NA","NA"),
  date3=c("23/6/2006", "24/12/2006", "18/2/2006", "NA","NA"),
  s2=c("NA","NA",2,"NA","NA")
 ),
.Names = c("id", "date1","date2","s1","date3","s2"),
 class = "data.frame",
 row.names = c(NA,-5L),
 col_types = c("numeric", "date","date","numeric","date","numeric")
 )

我尝试了以下代码

df$x1<-ifelse(df$date1<=df$date2,3,s1)
df$x2<-ifelse(df$date1<=df$date3,3,s2)

它给出

  id      date1      date2 s1      date3 s2 x1 x2
1  1   1/4/2004   8/6/2002  1  23/6/2006 NA  3  3
2  2   3/8/2004  11/5/2004  2 24/12/2006 NA  2 NA
3  3         NA   3/5/2004  1  18/2/2006  2  1  2
4  4 13/10/2004 25/11/2004 NA         NA NA  3  3
5  5  11/3/2003  21/1/2004 NA         NA NA  3  3

由此，由于“ 3/8/2004”小于“ 24/12/2006”，因此“ x2”列中的“ NA”未响应该代码，因此我希望用3代替“ “ x2”列中的“ NA”。任何人都可以澄清这是为什么发生以及如何解决。非常感谢您的帮助。

Answer 1

日期列在数据中是字符类型。

class(df$date1)
#[1] "character"

我们首先需要将它们转换为Date对象，然后进行比较

cols <- paste0("date", 1:3)
df[cols] <- lapply(df[cols], as.Date, "%d/%m/%Y")
df$x1<-ifelse(df$date1 <= df$date2, 3, df$s1)
df$x2<-ifelse(df$date1 <= df$date3, 3, df$s2)

df
#  id      date1      date2 s1      date3 s2   x1 x2
#1  1 2004-04-01 2002-06-08  1 2006-06-23 NA    1  3
#2  2 2004-08-03 2004-05-11  2 2006-12-24 NA    2  3
#3  3       <NA> 2004-05-03  1 2006-02-18  2 <NA> NA
#4  4 2004-10-13 2004-11-25 NA       <NA> NA    3 NA
#5  5 2003-03-11 2004-01-21 NA       <NA> NA    3 NA

或者根据您需要的输出，也可以将dplyr与replace一起使用

library(dplyr)
df %>%
  mutate_at(vars(starts_with("date")), as.Date, "%d/%m/%Y") %>%
  mutate(x1 = replace(s1, date1 <= date2, 3), 
         x2 = replace(s2, date1 <= date3, 3))

对日期使用“小于”运算符

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