替换多行文本列中的第一行字符

Question

我试图在案文中将"o“替换为”·“：

·指导该部的技术工作 ·作为项目负责人履行监督和管理职责 确定方向以确保目标和目的 O选择管理人员和其他关键人员 与执行同事合作，制定和执行公司计划和部门战略。 监督部门年度财务计划和预算的编制和执行 O管理绩优薪酬 ·履行分配的其他职责

因为这些都是我尝试过的

test<- sub(test, pattern = "o ", replacement = "• ")  # does not work
test<- gsub(test, pattern = "^o ", replacement = "• ")  # does not work
test<- gsub(test, pattern = "o ", replacement = "• ") # works but it also replaces to to t•

为什么"^o“不能工作，因为它只出现在每一行的开头。

Answer 1

这些都是一个单一的值吗？如果是这样的话，请使用查找后的方法在换行符或字符串开始之后找到o：

test2 <- gsub(test, pattern = "(?<=\n|\r|^)o ", replacement = "• ", perl = TRUE)
cat(test2)

• Direct the Department’s technical

• Perform supervisory and managerial responsibilities as leader of the program

• Set direction to ensure goals and objectives

• Select management and other key personnel

• Collaborate with executive colleagues to develop and execute corporate initiatives and department strategy

• Oversee the preparation and execution of department’s Annual Financial Plan and budget

• Manage merit pay

• Perform other duties as assigned

或者，将每一行的值拆分为单独的值，然后使用原始regex：

test3 <- gsub(unlist(strsplit(test, "\n|\r")), pattern = "^o ", replacement = "• ")
test3

 [1] "• Direct the Department’s technical"                                                                         
 [2] ""                                                                                                            
 [3] "• Perform supervisory and managerial responsibilities as leader of the program"                              
 [4] ""                                                                                                            
 [5] "• Set direction to ensure goals and objectives"                                                              
 [6] ""                                                                                                            
 [7] "• Select management and other key personnel"                                                                 
 [8] ""                                                                                                            
 [9] "• Collaborate with executive colleagues to develop and execute corporate initiatives and department strategy"
[10] ""                                                                                                            
[11] "• Oversee the preparation and execution of department’s Annual Financial Plan and budget"                    
[12] ""                                                                                                            
[13] "• Manage merit pay"                                                                                          
[14] ""                                                                                                            
[15] "• Perform other duties as assigned"   

Answer 2

这里不需要任何查找，请使用^和(?m)标志：

test <- gsub(test, pattern = "(?m)^o ", replacement = "• ", perl=TRUE)

(?m)重新定义了^锚点的行为，如果您指定了m标志，这意味着“行的开始”。

见在线R演示

test <- "• Direct the Department’s technical\n\no Set direction to ensure goals and objectives\n\no Select management and other key personnel"
cat(gsub(test, pattern = "(?m)^o ", replacement = "• ", perl=TRUE))

输出：

• Direct the Department’s technical

• Set direction to ensure goals and objectives

• Select management and other key personnel