正则表达式
R 中级
Filip Schouwenaars
DataCamp Instructor
正则表达式
- （元）字符序列
- 模式存在性
- 模式替换
- 模式提取
grep(),grepl()sub(),gsub()
grepl()
animals <- c("cat", "moose", "impala", "ant", "kiwi")
grepl(pattern = <regex>, x = <string>)
grepl(pattern = "a", x = animals)
TRUE FALSE TRUE TRUE FALSE
grepl()
grepl(pattern = "^a", x = animals)
FALSE FALSE FALSE TRUE FALSE
grepl(pattern = "a$", x = animals)
FALSE FALSE TRUE FALSE FALSE
?regex
grep()
animals <- c("cat", "moose", "impala", "ant", "kiwi")
grepl(pattern = "a", x = animals)
TRUE FALSE TRUE TRUE FALSE
grep(pattern = "a", x = animals)
1 3 4
grep()
which(grepl(pattern = "a", x = animals))
1 3 4
grep(pattern = "^a", x = animals)
4
sub(), gsub()
animals <- c("cat", "moose", "impala", "ant", "kiwi")
sub(pattern = <regex>, replacement = <str>, x = <str>)
sub(pattern = "a", replacement = "o", x = animals)
"cot" "moose" "impola" "ont" "kiwi"
gsub(pattern = "a", replacement = "o", x = animals)
"cot" "moose" "impolo" "ont" "kiwi"
sub(), gsub()
animals <- c("cat", "moose", "impala", "ant", "kiwi")
sub(pattern = "a", replacement = "o", x = animals)
"cot" "moose" "impola" "ont" "kiwi"
gsub(pattern = "a", replacement = "o", x = animals)
"cot" "moose" "impolo" "ont" "kiwi"
sub(), gsub()
gsub(pattern = "a|i", replacement = "_", x = animals)
"c_t" "moose" "_mp_l_" "_nt" "k_w_"
gsub(pattern = "a|i|o", replacement = "_", x = animals)
"c_t" "m__se" "_mp_l_" "_nt" "k_w_"
Passons à la pratique !
R 中级
