我们可以使用str_detect函数来检查单个字符串或字符串向量是小写还是大写。与str_detect函数一起，我们需要使用大写或小写来检查字符串是小写还是大写，并且输出将以TRUE或FALSE形式返回，如果字符串是小写并且通过str_detect函数传递小写，则输出将为TRUE，反之亦然。
x1<-letters[1:26] x1
输出结果
[1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" [20] "t" "u" "v" "w" "x" "y" "z"
str_detect(x1,"[[:upper:]]")
输出结果
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE [13] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE [25] FALSE FALSE
x2<-LETTERS[1:26] x2
输出结果
[1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R" "S" [20] "T" "U" "V" "W" "X" "Y" "Z"
str_detect(x2,"[[:upper:]]")
输出结果
[1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE [16] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
x3<-"india" x3
输出结果
[1] "india"
str_detect(x3,"[[:upper:]]")
输出结果
[1] FALSE
x4<-c("abc","abcd","abcde","bacdef")
x4输出结果
[1] "abc" "abcd" "abcde" "bacdef"
str_detect(x4,"[[:upper:]]")
输出结果
[1] FALSE FALSE FALSE FALSE
x5<-c("AK", "AL", "AR", "AS", "AZ", "CA", "CO", "CT", "DC", "DE", "FL", "GA", "GU", "HI", "IA", "ID", "IL", "IN", "KS", "KY", "LA", "MA", "MD", "ME", "MI", "MN", "MO", "MP", "MS", "MT", "NC", "ND", "NE", "NH", "NJ", "NM", "NV", "NY", "OH", "OK", "OR", "PA", "PR", "RI", "SC", "SD", "TN", "TX", "UM", "UT", "VA", "VI", "VT", "WA", "WI", "WV", "WY")
x5输出结果
[1] "AK" "AL" "AR" "AS" "AZ" "CA" "CO" "CT" "DC" "DE" "FL" "GA" "GU" "HI" "IA" [16] "ID" "IL" "IN" "KS" "KY" "LA" "MA" "MD" "ME" "MI" "MN" "MO" "MP" "MS" "MT" [31] "NC" "ND" "NE" "NH" "NJ" "NM" "NV" "NY" "OH" "OK" "OR" "PA" "PR" "RI" "SC" [46] "SD" "TN" "TX" "UM" "UT" "VA" "VI" "VT" "WA" "WI" "WV" "WY"
str_detect(x5,"[[:upper:]]")
输出结果
[1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE [16] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE [31] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE [46] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
x6<-c("alabama", "alaska", "american samoa", "arizona", "arkansas", "california", "colorado", "connecticut", "delaware", "district of columbia", "florida", "georgia", "guam", "hawaii", "idaho", "illinois", "indiana", "iowa", "kansas", "kentucky", "louisiana", "maine", "maryland", "massachusetts", "michigan", "minnesota", "minor outlying islands", "mississippi", "missouri", "montana", "nebraska", "nevada", "new hampshire", "new jersey", "new mexico", "new york", "north carolina", "north dakota", "northern mariana islands", "ohio", "oklahoma", "oregon", "pennsylvania", "puerto rico", "rhode island", "south carolina", "south dakota", "tennessee", "texas", "u.s. virgin islands", "utah", "vermont", "virginia", "washington", "west virginia", "wisconsin", "wyoming")
x6输出结果
[1] "alabama" "alaska" [3] "american samoa" "arizona" [5] "arkansas" "california" [7] "colorado" "connecticut" [9] "delaware" "district of columbia" [11] "florida" "georgia" [13] "guam" "hawaii" [15] "idaho" "illinois" [17] "indiana" "iowa" [19] "kansas" "kentucky" [21] "louisiana" "maine" [23] "maryland" "massachusetts" [25] "michigan" "minnesota" [27] "minor outlying islands" "mississippi" [29] "missouri" "montana" [31] "nebraska" "nevada" [33] "new hampshire" "new jersey" [35] "new mexico" "new york" [37] "north carolina" "north dakota" [39] "northern mariana islands" "ohio" [41] "oklahoma" "oregon" [43] "pennsylvania" "puerto rico" [45] "rhode island" "south carolina" [47] "south dakota" "tennessee" [49] "texas" "u.s. virgin islands" [51] "utah" "vermont" [53] "virginia" "washington" [55] "west virginia" "wisconsin" [57] "wyoming"
str_detect(x6,"[[:upper:]]")
输出结果
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE [13] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE [25] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE [37] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE [49] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE