如何在 R 中写入或更改文件中的某些字符？

Question

我有一个 PRM 文件，它是一种文本文件。我想改变其中的一些字符。例如，“md = minf;”到“md = maxf;”和“ls = 1”到“ls = 3”。 你能指导我如何改变它吗？我不知道在这种情况下如何使用 WriteLines 函数？

> setwd("C:/Users/Documents/CONN")
> fileName <- "Hmin.PRM"
> conn <- file(fileName,open="r")
> linn <-readLines(conn)
> for (i in 1:length(linn)){
+   print(linn[i])
+ }
[1] ""
[1] "begin_pop = \"p1\";"
[1] "   beginfounder;"
[1] "      male   [n =   20, pop = \"hp\"];"
[1] "      female [n = 400, pop = \"hp\"];"
[1] "   endfounder;"
[1] "   ls  = 1;           "
[1] "   pmp = 0.5;                 "
[1] "   ng  = 10;                  "
[1] "   md  = minf;                 "
[1] "   sr  = 0.5;                 "
[1] "   dr  = 0.3;                 "
[1] "   sd  = ebv /h;             "
[1] "   cd  = ebv /l;              "
[1] "   ebvest = true_av;"
[1] "   begpop;"
[1] "        ld /maft 0.1;"
[1] "\t   crossover;"
[1] "        data;"
[1] "        stat;"
[1] "        genotype/gen 8 9 10;"
[1] "   endpop;"
[1] "end_pop;"
[1] "  "
> close(conn)

Answer 1

linn <- c("begin_pop = \\p1\\;", "   beginfounder;", "      male   [n =   20, pop = \\hp\\];", "      female [n = 400, pop = \\hp\\];", "   endfounder;", "   ls  = 1;", "   pmp = 0.5;", "   ng  = 10;", "   md  = minf;", "   sr  = 0.5;", "   dr  = 0.3;", "   sd  = ebv /h;", "   cd  = ebv /l;", "   ebvest = true_av;", "   begpop;", "        ld /maft 0.1;", "\t   crossover;", "        data;", "        stat;", "        genotype/gen 8 9 10;", "   endpop;", "end_pop;")

gsub("\\b(ls\\s*=\\s*)1", "\\1 3",
     gsub("\\b(md\\s*=\\s*)minf", "\\1maxf", linn))
#  [1] "begin_pop = \\p1\\;"                    "   beginfounder;"                      
#  [3] "      male   [n =   20, pop = \\hp\\];" "      female [n = 400, pop = \\hp\\];" 
#  [5] "   endfounder;"                         "   ls  =  3;"                          
#  [7] "   pmp = 0.5;"                          "   ng  = 10;"                          
#  [9] "   md  = maxf;"                         "   sr  = 0.5;"                         
# [11] "   dr  = 0.3;"                          "   sd  = ebv /h;"                      
# [13] "   cd  = ebv /l;"                       "   ebvest = true_av;"                  
# [15] "   begpop;"                             "        ld /maft 0.1;"                 
# [17] "\t   crossover;"                         "        data;"                         
# [19] "        stat;"                          "        genotype/gen 8 9 10;"          
# [21] "   endpop;"                             "end_pop;"                              

正则表达式的解释：

• \\b是一个单词边界，所以我们匹配md 但不是 amd；
• \\s* 是零个或多个空格
• (..) 是一个匹配组，（在本例中）我们希望将其带回替代品;
• \\1 正在回忆第一个匹配组，
• 这是我在 ls = 和 3 之间引入空格的唯一原因（而我没有添加maxf 之前的空格）是我希望 \\1 和 \\13 之间在视觉上绝对没有歧义，建议 13 个匹配组。 R 对后者没有问题，但我想我应该在正则表达式中保持清晰。