R-字符串操作

Question

我正在使用一个由“readLines”命令生成的字符向量。

在这个向量的某一部分，我有以下内容：

> metadata[147:157]
 [1] "    RADIANCE_MULT_BAND_1 = 1.2852E-02"  "    RADIANCE_MULT_BAND_2 = 1.3161E-02" 
 [3] "    RADIANCE_MULT_BAND_3 = 1.2128E-02"  "    RADIANCE_MULT_BAND_4 = 1.0227E-02" 
 [5] "    RADIANCE_MULT_BAND_5 = 6.2583E-03"  "    RADIANCE_MULT_BAND_6 = 1.5564E-03" 
 [7] "    RADIANCE_MULT_BAND_7 = 5.2458E-04"  "    RADIANCE_MULT_BAND_8 = 1.1574E-02" 
 [9] "    RADIANCE_MULT_BAND_9 = 2.4459E-03"  "    RADIANCE_MULT_BAND_10 = 3.3420E-04"
[11] "    RADIANCE_MULT_BAND_11 = 3.3420E-04"

我需要的是只得到每一行的值，或者更好的，所有在等号之后出现的东西。就像这样：

factor <- as.numeric (everything coming after the equal symbol (metadata[147:157]))

我想这可以用gsub来完成，但是我在文档中没有发现任何有用的东西。有什么想法吗？

非常感谢蒂亚戈。

Answer 1

你可以试试regex

as.numeric(sub(".*= ?", "", metadata))
#[1] 0.01285200 0.01316100 0.01212800 0.01022700 0.00625830 0.00155640
#[7] 0.00052458 0.01157400 0.00244590 0.00033420 0.00033420

数据

metadata <- c("    RADIANCE_MULT_BAND_1 = 1.2852E-02", 
"    RADIANCE_MULT_BAND_2 = 1.3161E-02",
"    RADIANCE_MULT_BAND_3 = 1.2128E-02", 
"    RADIANCE_MULT_BAND_4 = 1.0227E-02",
"    RADIANCE_MULT_BAND_5 = 6.2583E-03",
"    RADIANCE_MULT_BAND_6 = 1.5564E-03", 
"    RADIANCE_MULT_BAND_7 = 5.2458E-04",
"    RADIANCE_MULT_BAND_8 = 1.1574E-02", 
"    RADIANCE_MULT_BAND_9 = 2.4459E-03",
"    RADIANCE_MULT_BAND_10 = 3.3420E-04", 
"    RADIANCE_MULT_BAND_11 = 3.3420E-04")