有时候使用
如果代码包含在脚本文件中,
有人能告诉我为什么
print
命令打印 data.table
时需要尝试两次才能成功:> library(data.table)
>
> rm(list=ls())
>
> Tbl <- fread( input = "Nr; Value
+ Nr 1;46.73
+ Nr 2;49.02
+ Nr 3;50.62
+ Nr 4;49.80
+ Nr 5;50.15",
+ sep = ";",
+ header = TRUE,
+ colClasses = c("character","numeric") )
> print(Tbl)
Nr Value
1: Nr 1 46.73
2: Nr 2 49.02
3: Nr 3 50.62
4: Nr 4 49.80
5: Nr 5 50.15
> Tbl <- Tbl[, Nr := as.numeric( gsub( "Nr ", "", Tbl$Nr ))]
> print(Tbl)
> print(Tbl)
Nr Value
1: 1 46.73
2: 2 49.02
3: 3 50.62
4: 4 49.80
5: 5 50.15
>
不是data.frame
类型的数据:
> rm(list=ls())
>
> DF <- read.table( text = "Nr; Value
+ Nr 1;46.73
+ Nr 2;49.02
+ Nr 3;50.62
+ Nr 4;49.80
+ Nr 5;50.15",
+ sep = ";",
+ header = TRUE,
+ colClasses = c("character","numeric"))
>
> DF$Nr <- as.numeric( gsub( "Nr ", "", DF$Nr ))
> print(DF)
Nr Value
1 1 46.73
2 2 49.02
3 3 50.62
4 4 49.80
5 5 50.15
>
如果代码包含在脚本文件中,
data.table
会立即打印出来。> source(path_to_Script_1,echo=TRUE,prompt.echo="(script) ",max.deparse.length=500)
(script) library(data.table)
(script) rm(list=ls())
(script) Tbl <- fread( input = "Nr; Value
+ Nr 1;46.73
+ Nr 2;49.02
+ Nr 3;50.62
+ Nr 4;49.80
+ Nr 5;50.15",
+ sep = ";",
+ header = TRUE,
+ colClasses = c("character","numeric") )
(script) Tbl <- Tbl[, Nr := as.numeric( gsub( "Nr ", "", Tbl$Nr ))]
(script) print(Tbl)
Nr Value
1: 1 46.73
2: 2 49.02
3: 3 50.62
4: 4 49.80
5: 5 50.15
>
但是如果脚本文件中省略了print(Tbl)
,则控制台上的print
需要再次尝试两次:
> source(path_to_Script_2,echo=TRUE,prompt.echo="(script) ",max.deparse.length=500)
(script) library(data.table)
(script) rm(list=ls())
(script) Tbl <- fread( input = "Nr; Value
+ Nr 1;46.73
+ Nr 2;49.02
+ Nr 3;50.62
+ Nr 4;49.80
+ Nr 5;50.15",
+ sep = ";",
+ header = TRUE,
+ colClasses = c("character","numeric") )
(script) Tbl <- Tbl[, Nr := as.numeric( gsub( "Nr ", "", Tbl$Nr ))]
> print(Tbl)
> print(Tbl)
Nr Value
1: 1 46.73
2: 2 49.02
3: 3 50.62
4: 4 49.80
5: 5 50.15
>
有人能告诉我为什么
print
需要尝试两次吗? 我正在使用R版本3.2.2:> R.version
_
platform x86_64-w64-mingw32
arch x86_64
os mingw32
system x86_64, mingw32
status
major 3
minor 2.2
year 2015
month 08
day 14
svn rev 69053
language R
version.string R version 3.2.2 (2015-08-14)
nickname Fire Safety
操作系统是Windows 7。
print(Tbl)
包含在脚本文件中和不包含有什么区别? - mra68Tbl <-
?这是一个无用的复制。可以直接使用Tbl[, Nr := as.numeric( gsub( "Nr ", "", Tbl$Nr ))]
,该语句会直接修改数据表中的内容。 - Roland[ ]
。 - MichaelChiricorm(list = ls())
,以免有人复制粘贴并运行而没有仔细阅读。如果您需要删除特定对象以使示例正常工作,请具体说明rm(Tbl)
。 - Gregor Thomas