Question

我的数据框rep如下所示：

> head(rep)
     position chrom  value label  
[1,] "17408"  "chr1" "0"   "miRNA"
[2,] "17409"  "chr1" "0"   "miRNA"
[3,] "17410"  "chr1" "0"   "miRNA"
[4,] "17411"  "chr1" "0"   "miRNA"
[5,] "17412"  "chr1" "0"   "miRNA"
[6,] "17413"  "chr1" "0"   "miRNA"

如何从所有元素中删除引号？

注意：rep$position和rep$value应为numeric类型，rep$chrom和rep$label应为character类型。

Answer 1

两个步骤：1）去除引号，2）相应地转换列：

数据

x <- read.table(text='
position chrom  value label  
"\\"17408\\""  "\\"chr1\\"" "\\"0\\""   "\\"miRNA\\""
"\\"17409\\""  "\\"chr1\\"" "\\"0\\""   "\\"miRNA\\""'
, header=T)

1）摆脱引号

library(stringr)
library(plyr)

del <- colwise(function(x) str_replace_all(x, '\"', ""))
x <- del(x)

2）相应地转换列

num <- colwise(as.numeric)    
x[c(1,3)] <- num(x[c(1,3)])
x

  position chrom value label
1    17408  chr1     0 miRNA
2    17409  chr1     0 miRNA

Answer 2

如@Roland所示，您有一个matrix，而不是data.frame，这些方法有不同的默认print方法。坚持使用matrix，您可以在quote = FALSE中明确设置print，也可以使用noquote。

这是一个基本的例子：

## Sample data
x <- matrix(c(17, "chr1", 0, "miRNA", 18, "chr1", 0, "miRNA"), nrow = 2, 
            byrow = TRUE, dimnames = list(
              NULL, c("position", "chrom", "value", "label")))

## Default printing
x
#      position chrom  value label  
# [1,] "17"     "chr1" "0"   "miRNA"
# [2,] "18"     "chr1" "0"   "miRNA"

## Two options to make the quotes disappear
print(x, quote = FALSE)
#      position chrom value label
# [1,] 17       chr1  0     miRNA
# [2,] 18       chr1  0     miRNA
noquote(x)
#      position chrom value label
# [1,] 17       chr1  0     miRNA
# [2,] 18       chr1  0     miRNA

另外，正如您自己想出的那样，将matrix转换为data.frame会使引号消失。如果每列是不同类型的数据（数字，字符，因子等），data.frame是一种更适合保存数据的结构。但是，将matrix转换为data.frame并不会自动为您转换列。相反，您可以使用type.convert（在使用data.frame和系列创建read.table时也会使用）：

y <- data.frame(x, stringsAsFactors = FALSE)
str(y)
# 'data.frame':  2 obs. of  4 variables:
#  $ position: chr  "17" "18"
#  $ chrom   : chr  "chr1" "chr1"
#  $ value   : chr  "0" "0"
#  $ label   : chr  "miRNA" "miRNA"
y[] <- lapply(y, type.convert)
str(y)
# 'data.frame':  2 obs. of  4 variables:
#  $ position: int  17 18
#  $ chrom   : Factor w/ 1 level "chr1": 1 1
#  $ value   : int  0 0
#  $ label   : Factor w/ 1 level "miRNA": 1 1
y
#   position chrom value label
# 1       17  chr1     0 miRNA
# 2       18  chr1     0 miRNA

Answer 3

我想我找到了答案。我所拥有的不是data.frame而是矩阵。将它转换为data.frame摆脱了引号。我仍然想知道为什么......

rep <- data.frame(rep)
> head(rep)
  position chrom value label
1    17408  chr1     0 miRNA
2    17409  chr1     0 miRNA
3    17410  chr1     0 miRNA
4    17411  chr1     0 miRNA
5    17412  chr1     0 miRNA
6    17413  chr1     0 miRNA

从数据框中删除所有引号

3 个答案: