如何从R中的字符串中删除+(加号)? [英] How to remove + (plus sign) from string in R?

问题描述

说我使用gsub并想从字符串中删除以下(=，+，-)符号并替换为下划线.

Say I use gsub and want to remove the following (=,+,-) sign from the string and replace with an underscore.

有人可以描述当我尝试使用带加号(+)的gsub时发生了什么.

Can someone describe what is going on when I try to use the gsub with a plus sign (+).

test<- "sandwich=bread-mustard+ketchup"
# [1] "sandwich=bread-mustard+ketchup"

test<-gsub("-","_",test)
# [1] "sandwich=bread_mustard+ketchup"

test<-gsub("=","_",test)
# [1] "sandwich_bread_mustard+ketchup"

test<-gsub("+","_",test)
#[1] "_s_a_n_d_w_i_c_h___b_r_e_a_d___m_u_s_t_a_r_d_+_k_e_t_c_h_u_p_"

推荐答案

尝试

test<- "sandwich=bread-mustard+ketchup"
test<-gsub("\\+","_",test)
test
[1] "sandwich=bread-mustard_ketchup"

+是一个特殊字符.您需要逃脱它.例如，与.相同.如果您使用Google regex或正则表达式，则会找到相应的特殊字符列表.例如，描述此处 +表示1 or more of previous expression.有关特殊字符，正则表达式和R的更多信息，请参见此处或此处.

+ is a special character. You need to escape it. Same as, for instance, .. If you google regex or regular expressions, you will find the corresponding lists of special characters. For instance, here + is described to indicate 1 or more of previous expression. More about special characters, regular expressions and R can be found here or here.

一般来说，使用以下代码可以更有效地编写您的上述代码:

On a more general note, your above code could be written more efficiently by using:

 test<- "sandwich=bread-mustard+ketchup"
 test<-gsub("[-|=|\\+]","_",test)
 test
 [1] "sandwich_bread_mustard_ketchup"

在这里，我使用的结构基本上可以理解为[either this or that or something else]，其中|对应于or.

Here I have used a construct that can basically be read as [either this or that or something else], where | corresponds to or.

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