[英]Why does reshape2 melt return value = NA for me?
Why does reshape2 melt
return value
= NA
for me? 为什么reshape2
melt
返回value
= NA
?
It works for me with reshape, but not with reshape2: 它可以重塑,但不是reshape2:
Here is an example datafile: 这是一个示例数据文件:
"","station_id","year","month","day","h1","h2","h3","h4","h5","h6","h7","h8","h9","h10","h11","h12","h13","h14","h15","h16","h17","h18","h19","h20","h21","h22","h23","h24"
"1",1,2004,1,1,46,46,45,41,39,35,33,33,36,47,53,54,55,55,55,55,52,46,40,40,39,38,40,41
"2",1,2004,1,2,43,44,46,46,47,47,47,47,47,47,47,49,52,56,54,56,57,53,50,47,46,45,45,45
"3",1,2004,1,3,45,46,46,44,43,46,46,47,51,55,56,59,65,68,69,68,68,65,64,63,62,63,63,62
"4",1,2004,1,4,63,62,62,62,60,60,60,62,60,64,64,66,71,70,71,72,71,68,67,67,65,64,65,64
"5",1,2004,1,5,64,63,65,64,64,64,64,64,65,66,66,67,68,68,66,66,66,66,63,54,52,49,47,47
"6",1,2004,1,6,47,46,45,43,41,41,39,39,40,43,45,44,45,46,46,46,45,39,39,39,38,36,32,32
Let's say it is saved as /tmp/foo.csv
, then: 假设它保存为
/tmp/foo.csv
,然后:
Using reshape: 使用重塑:
$ R
...
Type 'q()' to quit R.
> library("reshape")
Loading required package: plyr
Attaching package: ‘reshape’
The following object(s) are masked from ‘package:plyr’:
rename, round_any
> hlist <- NULL; for(z in 1:24) { hlist <- cbind(hlist, sprintf("h%d",z)) }
>
> thh <- read.csv('/tmp/foo.csv')
> thm <- melt(thh,measure.vars=hlist,variable="hour")
> head(thm)
station_id year month day hour value
1 1 2004 1 1 h1 46
2 1 2004 1 2 h1 43
3 1 2004 1 3 h1 45
4 1 2004 1 4 h1 63
5 1 2004 1 5 h1 64
6 1 2004 1 6 h1 47
> q()
Using reshape2: 使用reshape2:
$ R
...
Type 'q()' to quit R.
> library("reshape2")
> hlist <- NULL; for(z in 1:24) { hlist <- cbind(hlist, sprintf("h%d",z)) }
>
> thh <- read.csv('/tmp/foo.csv')
> thm <- melt(thh,measure.vars=hlist,variable="hour")
> head(thm)
station_id year month day hour value
1 1 2004 1 1 h1 NA
2 1 2004 1 2 h1 NA
3 1 2004 1 3 h1 NA
4 1 2004 1 4 h1 NA
5 1 2004 1 5 h1 NA
6 1 2004 1 6 h1 NA
> q()
You can see that using library("reshape")
, the value
column has numbers, but for libary("reshape2")
, it has NA
, for the same data. 您可以看到使用
library("reshape")
, value
列具有数字,但对于libary("reshape2")
,它具有NA
,用于相同的数据。
There are better ways to do what you are trying to do. 有更好的方法来做你想做的事情。
All of the following would work with melt()
from reshape2
: 所有以下内容都适用于
reshape2
melt()
:
# Not using hlist
melt(th, measure.vars=5:ncol(th), variable="hour")
melt(th, id.vars=1:4, variable="hour")
# Using your hlist
hlist <- NULL; for(z in 1:24) { hlist <- cbind(hlist, sprintf("h%d",z)) }
melt(th, measure.vars=as.vector(hlist), variable="hour")
# Using an alternative hlist
hlist <- paste0("h", 1:24)
melt(th, measure.vars=hlist, variable="hour")
It seems like melt()
from "reshape" accepts a matrix as an input for measure.vars
, but melt()
from "reshape2" does not (which I find more reasonable). 这似乎是
melt()
从“重塑”接受一个矩阵作为输入measure.vars
,但melt()
从“reshape2”没有(我觉得这更合理)。
FYI, below is a start-to-finish way that you can share this problem in a way that is convenient for other Stack Overflow users to copy and paste: 仅供参考,以下是一种从头到尾的方式,您可以通过方便其他Stack Overflow用户复制和粘贴的方式分享此问题:
# Use set.seed when you want to use random numbers
# but want others to have the same data as you.
set.seed(1)
# Make up some data that mimics your actual dataset
# Does not have to be your exact dataset
th <- cbind(
data.frame(station = rep(LETTERS[1:3], each = 3),
year = 2004, month = rep(1:3, times = 3)),
setNames(data.frame(
matrix(sample(100, 45, replace = TRUE), nrow = 9)),
paste0("h", 1:5)))
hlist <- NULL; for(z in 1:5) { hlist <- cbind(hlist, sprintf("h%d",z)) }
# Cleanup any unnecessary stuff that your code leaves behind in the workspace
rm(z)
Now, demonstrate your problem. 现在,展示你的问题。 You can use
detach(package:package_name)
instead of having to quit and restart R. 您可以使用
detach(package:package_name)
而不必退出并重新启动R.
library(reshape)
head(melt(th, measure.vars = hlist, variable = "hour"))
# station year month hour value
# 1 A 2004 1 h1 27
# 2 A 2004 2 h1 38
# 3 A 2004 3 h1 58
# 4 B 2004 1 h1 91
# 5 B 2004 2 h1 21
# 6 B 2004 3 h1 90
detach(package:reshape)
library(reshape2)
head(melt(th, measure.vars = hlist, variable = "hour"))
# station year month hour value
# 1 A 2004 1 h1 <NA>
# 2 A 2004 2 h1 <NA>
# 3 A 2004 3 h1 <NA>
# 4 B 2004 1 h1 <NA>
# 5 B 2004 2 h1 <NA>
# 6 B 2004 3 h1 <NA>
detach(package:reshape2)
Hope this helps! 希望这可以帮助!
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