R语言中的字符处理

R语言中的字符处理

 (2011-07-10 22:29:48)

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标签：  r语言   字符处理   字符串   连接   分割

分类： R

R的字符串处理能力还是很强大的，具体有base包的几个函数和stringr包。

1.计算字符串的字符数

nchar() 

2. 字符串连接
paste(..., sep = " ", collapse = NULL)，其中collpase参数可将多个字符串连接成一个。

=====================================

> paste(letters[1:5], "_1", sep = '')

[1] "a_1" "b_1" "c_1" "d_1" "e_1"

> paste(letters[1:5], collapse='_')

[1] "a_b_c_d_e"

=====================================

3. 字符串分割

3.1 分隔符截取
strsplit(x, split, extended = TRUE, fixed = FALSE, perl = FALSE)
=================================================================================
QWE <- c("QWERTYUIOPASDFGHJKLZXCVBNM")
> unlist(strsplit(QWE, ""))
 [1] "Q" "W" "E" "R" "T" "Y" "U" "I" "O" "P" "A" "S" "D" "F" "G" "H" "J" "K" "L"
[20] "Z" "X" "C" "V" "B" "N" "M"

> xtest  #将xtest表示化成小时为单位的时间表示形式，以便用于坐标轴显示
 [1] "0:00:04"  "0:53:18"  "1:53:18"  "2:53:17"  "3:53:16"  "4:53:16"
 [7] "5:53:16"  "6:53:16"  "7:53:16"  "8:53:16"  "9:53:15"  "10:53:14"
[13] "11:53:13" "12:53:13" "13:53:13" "14:53:13" "15:53:13" "16:53:13"
[19] "17:53:13" "18:53:13" "19:53:13" "20:53:13" "21:53:13" "22:53:13"
[25] "23:53:14"

> xtest <- as.data.frame(strsplit(xtest, split= ":"))
> xtest
  c..0....00....04.. c..0....53....18.. c..1....53....18.. c..2....53....17..
1                  0                  0                  1                  2
2                 00                 53                 53                 53
3                 04                 18                 18                 17
  c..3....53....16.. c..4....53....16.. c..5....53....16.. c..6....53....16..
1                  3