重塑数据集r

Question

我需要从长变成宽格式。我没有时间变量。为以后的数据集中的每个id创建一个时间变量，以便在基础r（而不是重塑包）中进行后续整形，最简单的方法是什么？

h<-seq(from=as.Date("2005-06-01"), to=as.Date("2008-06-30"), by=1) 

a<-data.frame(id=sample(c(1:100),300,replace=T),val=rnorm(n=300),date=sample(h,300,replace=T)) 

//中号

Answer 1

这里是一种可能的方法。它使用ave根据“id”发生的次数来创建一个“时间”变量，对我而言，这听起来就像您要查找的内容。

你的数据，但是订购（使用set.seed以便其他人可以复制它）：

set.seed(1) 
h <- seq(from=as.Date("2005-06-01"), 
     to=as.Date("2008-06-30"), by=1) 
a <- data.frame(id=sample(c(1:100), 300, replace=TRUE), 
       val=rnorm(n=300), 
       date=sample(h, 300, replace=TRUE)) 
rm(h) 
a <- a[order(a$id, a$date), ] 
rbind(head(a), tail(a)) 
#  id   val  date 
# 27 2 0.78763961 2007-08-25 
# 116 2 0.27005490 2008-03-05 
# 281 3 -2.03328560 2006-08-08 
# 47 3 1.44115771 2007-06-25 
# 133 4 1.32425863 2006-06-14 
# 228 5 -0.14587563 2006-10-15 
# 111 98 0.95101281 2008-04-29 
# 293 99 -0.01825971 2006-01-20 
# 139 99 0.43370215 2008-02-20 
# 121 100 -0.25893258 2005-06-07 
# 18 100 -1.42449465 2007-08-19 
# 104 100 -0.24766434 2008-05-11 

您将与8“时代”，通过使用table检查结束。

max(table(a$id)) 
# [1] 8 
a$time <- ave(a$id, a$id, FUN=seq_along) 
rbind(head(a), tail(a)) 
#  id   val  date time 
# 27 2 0.78763961 2007-08-25 1 
# 116 2 0.27005490 2008-03-05 2 
# 281 3 -2.03328560 2006-08-08 1 
# 47 3 1.44115771 2007-06-25 2 
# 133 4 1.32425863 2006-06-14 1 
# 228 5 -0.14587563 2006-10-15 1 
# 111 98 0.95101281 2008-04-29 1 
# 293 99 -0.01825971 2006-01-20 1 
# 139 99 0.43370215 2008-02-20 2 
# 121 100 -0.25893258 2005-06-07 1 
# 18 100 -1.42449465 2007-08-19 2 
# 104 100 -0.24766434 2008-05-11 3 
a.wide <- reshape(a, direction = "wide", idvar="id", timevar="time") 
a.wide[1:8, 1:8] 
#  id  val.1  date.1  val.2  date.2  val.3  date.3 val.4 
# 27 2 0.7876396 2007-08-25 0.2700549 2008-03-05  NA  <NA>  NA 
# 281 3 -2.0332856 2006-08-08 1.4411577 2007-06-25  NA  <NA>  NA 
# 133 4 1.3242586 2006-06-14   NA  <NA>  NA  <NA>  NA 
# 228 5 -0.1458756 2006-10-15 0.5929847 2008-03-31  NA  <NA>  NA 
# 299 6 0.2368037 2006-02-06 1.0341077 2006-10-07  NA  <NA>  NA 
# 10 7 1.8692906 2005-07-19 -0.4839749 2006-06-02 1.435070 2007-11-30 1.017754 
# 158 8 0.5672209 2006-08-28 -0.4075286 2006-11-11 -2.285236 2007-03-29  NA 
# 69 9 0.6422413 2008-06-20   NA  <NA>  NA  <NA>  NA 
names(a.wide) 
# [1] "id"  "val.1" "date.1" "val.2" "date.2" "val.3" "date.3" "val.4" 
# [9] "date.4" "val.5" "date.5" "val.6" "date.6" "val.7" "date.7" "val.8" 
# [17] "date.8"