Question

我正在尝试融化数据框，我得到了这个奇怪的错误。有什么想法吗？

str(zx7)
'data.frame':   519 obs. of  5 variables:
 $ calday.new: Date, format: "2011-01-03" "2011-01-04" "2011-01-05" "2011-01-06" ...
 $ A20    : Time-Series  from 1 to 519: 0 0 0 0 0 0 0 0 0 0 ...
 $ B20    : Time-Series  from 1 to 519: 0 0 0 0 0 0 0 0 0 0 ...
 $ C20    : Time-Series  from 1 to 519: 0 0 0 0 0 0 0 0 0 0 ...
 $ D20    : Time-Series  from 1 to 519: 0 0 0 0 0 0 0 0 0 0 ...

zx7.melt <- melt(zx7, id=c("calday.new"))
Error in `[<-.ts`(`*tmp*`, ri, value = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  : only replacement of elements is allowed

Answer 1

问题是旧的“reshape”包的melt()函数在遇到类ts的对象时不知道该怎么做。

所以，你有两个明显的选择（尽管可能还有更多）：

unclass在您ts数据之前当前被归类为melt()的变量：

zx7b <- zx7         # Make a backup, just in case
library(reshape)    # Notice this is "reshape", not "reshape2"
head(melt(zx7b, id=c("calday.new"))) # Doesn't work
# Error in `[<-.ts`(`*tmp*`, ri, value = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  : 
#   only replacement of elements is allowed

## Unclass the relevant columns from your data.frame
zx7b[sapply(zx7b, is.ts)] <- lapply(zx7b[sapply(zx7b, is.ts)],
                                    unclass)
head(melt(zx7b, id=c("calday.new")))
#   calday.new variable value
# 1 2011-01-03      A20     0
# 2 2011-01-04      A20     0
# 3 2011-01-05      A20     0
# 4 2011-01-06      A20     0
# 5 2011-01-07      A20     0
# 6 2011-01-08      A20     0

改为升级为“reshape2”，不需要取消分类。

library(reshape2) # Notice that this is reshape2!
head(melt(zx7, id=c("calday.new"))) # Melt the original data.frame
#   calday.new variable value
# 1 2011-01-03      A20     0
# 2 2011-01-04      A20     0
# 3 2011-01-05      A20     0
# 4 2011-01-06      A20     0
# 5 2011-01-07      A20     0
# 6 2011-01-08      A20     0

我没有花时间去做，但你可以从“reshape”软件包的每个版本检查melt.data.frame melt()方法的代码，看看差异在哪里。安装两个软件包，然后键入reshape2:::melt.data.frame和reshape:::melt.data.frame以查看基础功能。

R - 重塑 - 熔体错误

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