将面板数据从Long改为Wide[复制]

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这个问题已经有了答案:

How to reshape data from long to wide format? 8 answers
如何从长到宽的格式重塑数据?8回答

I would like to convert my panel data from long format to wide format. I know there are a number of other questions which hit on this subject, however, I do not believe any of them have the exact answers I am looking for.

我想把我的面板数据从长格式转换成宽格式。我知道在这个问题上还有很多其他的问题，但是，我不相信他们中的任何一个有我正在寻找的确切答案。

my.df <- data.frame(ID=rep(c("A","B","C"), 3), 
    TIME=rep(1:3, each=3), Price=1:9)
my.df

   ID TIME Price
1   A    1     1
2   B    1     2
3   C    1     3
4   A    2     4
5   B    2     5
6   C    2     6
7   A    3     7
8   B    3     8
9   C    3     9

来

  TIME Price-A Price-B Price-C
1    1       1       2       3
2    2       4       5       6
3    3       7       8       9

Thanks for any help you can provide! Francis

感谢您的帮助!弗朗西斯

2 个解决方案

#1

You can use reshape for this:

您可以使用重塑为此:

reshape(my.df,direction="wide", idvar = "TIME", timevar = "ID")


#    TIME Price.A Price.B Price.C
#     1       1       2       3
#     2       4       5       6
#     3       7       8       9

#2

Or you could use dcast from the reshape2 package:

或者可以使用reshape2包中的dcast:

require(reshape2)
dcast(my.df, TIME~ID, value.var="Price")

For this specific example, reshape is faster than dcast. But if the data.frame gets larger, dcast will be faster.

对于这个特定的示例，重塑比dcast要快。但是如果数据。frame变大，dcast会更快。

# your example data
require(microbenchmark)
microbenchmark(
  dcast(my.df, TIME~ID, value.var="Price")
  ,
  reshape(my.df,direction="wide", idvar = "TIME", timevar = "ID")
)
# Unit: milliseconds
#    expr      min       lq   median       uq      max  neval
#   dcast 2.655360 2.690616 2.718508 2.766484 4.396740    100
# reshape 2.156866 2.191007 2.221800 2.279147 3.896462    100

# my sample data
rows <- 10
LETTERS2 <- do.call(paste0, list(rep(LETTERS, 26), rep(LETTERS, each=26)))
LETTERS3 <- do.call(paste0, list(rep(LETTERS, 26), rep(LETTERS2, each=26)))
my.df <- data.frame(ID=rep(LETTERS3[1:rows], rows), 
                    TIME=rep(1:rows, each=rows), Price=1:(rows^2))
microbenchmark(
  dcast(my.df, TIME~ID, value.var="Price")
  ,
  reshape(my.df,direction="wide", idvar = "TIME", timevar = "ID")
)
# Unit: milliseconds
#   expr       min       lq   median       uq      max  neval
#  dcast  2.742831 2.795938 2.841681 2.912416 4.570789    100
# reshape 6.571011 6.667631 6.749746 6.857076 8.891662    100

#1