[英]How can I select two characters in a string?
I know that maybe is something of very easy to resolve but, looking for various example online, I did not find the right example to resolve my problem. 我知道这也许很容易解决,但是在网上寻找各种示例时,我没有找到解决问题的正确示例。
I have in a data.frame under a column a following phrase: 我在列下的data.frame中有以下短语:
ID
p_IIJSJ;o_OODJ;l_jjjjw;g_jjjdI
p_HHDU;o_WWj;l_WWOJ;g_jjjDI
I would like to select two words: the one who start with p_ and the one who start with g_ and eliminate all the rest which is between them.... do you have any suggestion about how make it? 我想选择两个词:一个以p_开头,一个以g_开头,并消除它们之间的所有其余词。...您对此有何建议? I'm trying with
gsub
but with no success at the moment. 我正在尝试使用
gsub
但目前没有成功。 Thank you a lot in advance 提前多谢
An approach with strrsplit
, 一种
strrsplit
的方法,
sapply(strsplit(x, ';'), function(i) paste(grep('p_|g_', i, value = TRUE), collapse = ';'))
#[1] "p_IIJSJ;g_jjjdI"
or if the order is always the same (as @Jaap mentions) 或顺序始终相同(如@Jaap所述)
sapply(strsplit(df$ID,';'), function(x) paste(x[c(1,4)], collapse=';'))
I suggest you use package stringr
which makes it easy: 我建议您使用
stringr
package stringr
:
library(stringr)
a <- "p_IIJSJ;o_OODJ;l_jjjjw;g_jjjdI"
b <- "p_HHDU;o_WWj;l_WWOJ;g_jjjDI"
str_extract(string = a, pattern = c("p_[a-zA-Z]+", "g_[a-zA-Z]+"))
# [1] "p_IIJSJ" "g_jjjdI"
str_extract(string = b, pattern = c("p_[a-zA-Z]+", "g_[a-zA-Z]+"))
# [1] "p_HHDU" "g_jjjDI"
We can use sub
我们可以使用
sub
sub(";*(p_\\w+).*;*(g_\\w+).*", "\\1;\\2", df1$ID)
#[1] "p_IIJSJ;g_jjjdI" "p_HHDU;g_jjjDI"
Or with gsub
或搭配
gsub
gsub("[^pg]_\\w+;", "", df1$ID)
#[1] "p_IIJSJ;g_jjjdI" "p_HHDU;g_jjjDI"
df1 <- structure(list(ID = c("p_IIJSJ;o_OODJ;l_jjjjw;g_jjjdI", "p_HHDU;o_WWj;l_WWOJ;g_jjjDI"
)), .Names = "ID", class = "data.frame", row.names = c(NA, -2L))
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