当measure.vars包含不在data.table中的变量时，melt.data.table可能会崩溃 [英] melt.data.table may crash when measure.vars contains variables not in data.table

问题描述

以下代码在我的安装中崩溃：

  library（data.table）
 library（reshape2）
x = data.table（a = c（1,2），b = c（2,3），c = c（3,4））
 melt（x，id.vars =a ）＃OK 
 melt（x，id.vars =a，measure.vars = c（c，d））＃崩溃
  

邮件如下：

  ***捕获segfault *** 
地址0x21000038，原因'内存未映射'
回溯：
 1：melt.data.table（x，id.vars =a，measure.vars = c c，d））
 2：melt（x，id.vars =a，measure.vars = c（c，d））
  
 
 
 
这里是sessionInfo（）
  R版本3.1.0（2014-04-10）
平台：x86_64-pc-linux-gnu（64位）
 
语言环境：
 [1] LC_CTYPE = en_US.UTF-8 LC_NUMERIC = C 
 [3] LC_TIME = ro_RO.UTF-8 LC_COLLATE = en_US.UTF-8 
 [5] LC_MONETARY = ro_RO.UTF-8 LC_MESSAGES = en_US.UTF-8 
 [7] LC_PAPER = ro_RO.UTF-8 LC_NAME = C 
 [9] LC_ADDRESS = C LC_TELEPHONE = C 
 [11] LC_MEASUREMENT = ro_RO.UTF-8 LC_IDENTIFICATION = C 
 
附加的基本包：
 [1] stats graphics grDevices utils数据集方法base 
> library（data.table）
 data.table 1.9.2对于帮助类型：help（data.table）
> library（reshape2）
> sessionInfo（）
 R版本3.1.0（2014-04-10）
平台：x86_64-pc-linux-gnu（64位）
 
语言环境：
 [1] LC_CTYPE = en_US.UTF-8 LC_NUMERIC = C 
 [3] LC_TIME = ro_RO.UTF-8 LC_COLLATE = en_US.UTF-8 
 [5] LC_MONETARY = ro_RO.UTF-8 LC_MESSAGES = en_US.UTF-8 
 [7] LC_PAPER = ro_RO.UTF-8 LC_NAME = C 
 [9] LC_ADDRESS = C LC_TELEPHONE = C 
 [11] LC_MEASUREMENT = ro_RO.UTF-8 LC_IDENTIFICATION = C 
 
附加的基本包：
 [1] stats graphics grDevices utils数据集方法base 
 
其他附加包：
 [1] reshape2_1。 4 data.table_1.9.2 
 
通过命名空间加载（未附加）：
 [1] plyr_1.8.1 Rcpp_0.11.1 stringr_0.6.2 
  
这可能是同一个问题：熔解data.table似乎崩溃RStudio？ 
解决方案
帖子和错误报告。现在，此问题已通过v1.9.3的提交1261 解决。从新闻：
 
 
 
 
  melt 现在会在 meaure.vars 不在数据而不是segfault。关闭＃699 。感谢vsalmendra对 SO上的这篇文章以及后续的错误报告。
 
 
 
 
如果问题仍然存在，请回复。
 
The following code crashes in my installation:
library(data.table)
library(reshape2)
x = data.table(a=c(1,2),b=c(2,3),c=c(3,4))
melt(x,id.vars="a") # OK
melt(x,id.vars="a",measure.vars=c("c","d")) # Crashes
The message is the following:
*** caught segfault ***
address 0x21000038, cause 'memory not mapped'
Traceback:
1: melt.data.table(x, id.vars = "a", measure.vars = c("c", "d"))
2: melt(x, id.vars = "a", measure.vars = c("c", "d"))
Here is the sessionInfo()
R version 3.1.0 (2014-04-10)
Platform: x86_64-pc-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=ro_RO.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=ro_RO.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=ro_RO.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=ro_RO.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     
> library(data.table)
data.table 1.9.2  For help type: help("data.table")
> library(reshape2)
> sessionInfo()
R version 3.1.0 (2014-04-10)
Platform: x86_64-pc-linux-gnu (64-bit)

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=ro_RO.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=ro_RO.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=ro_RO.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=ro_RO.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] reshape2_1.4     data.table_1.9.2

loaded via a namespace (and not attached):
[1] plyr_1.8.1    Rcpp_0.11.1   stringr_0.6.2
It may be the same problem reported here: melting data.table seems to crash RStudio?
解决方案
Thanks for the post and the bug report. This is now fixed with commit 1261 of v1.9.3. From NEWS:

  

  
melt now returns friendly error when meaure.vars are not in data instead of segfault. Closes #699. Thanks to vsalmendra for this post on SO and the subsequent bug report.
  
Please write back if the issue persists.

                        
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