当我想使用“as.numeric()”将一列从因子更改为数字时，最终数字与我导入的数字完全不同。
这是逗号引起的问题吗？真的很奇怪...
谢谢！
dput(datatest) 结构(list(HOURS.at.sea = structure(c(261L, 84L, 83L, 260L, 307L, 292L, 252L, 72L, 59L, 343L, 244L, 78L, 56L, 9L, 95) 291L, 254L, 69L, 65L, 267L, 283L, 1L, 80L, 169L, 1L, 115L, 67L, 75L, 3L, 309L, 59L, 33L, 52L, 5L, 5L, 2L, 7L, 7L 83L、21L、2L、53L、70L、19L、3L、57L、70L、22L、3L、58L、78L、36L、49L、2L、66L、115L、52L、14L、52L、72L、16L、7L 68L, 116L, 55L, 70L, 327L, 6L, 257L, 2L, 107L, 176L, 182L, 4L, 114L, 35L, 46L, 3L, 67L, 34L, 3,9L, 6L, 46L, 36L 52L、2L、69L、38L、85L、49L、70L、64L、70L、3L、1L、206L、231L、58L、55L、109L、212L、220L、56L、220L、53L、1L、3L 57L、55L、107L、217L、228L、52L、57L、105L、210L、231L、56L、55L、105L、215L、232L、55L、54L、28L、230L、8L、190L 57L、56L、96L、213L、228L、55L、57L、106L、217L、232L、58L、73L、110L、217L、233L、57L、59L、117L、7L、222L、233L、59L、56L、237L、237L、37L、319L 56L, 57L, 106L, 1L, 1L, 247L, 317L, 159L, 316L, 229L, 306L, 129L, 120L, 29L, 74L, 287L, 12L, 16L, 16L, 201L, 159L, 229L 180L, 76L, 281L, 86L, 79L, 258L, 83L, 1L, 229L, 23L, 132L, 56L, 59L, 76L, 115L, 110L, 28L, 236L, 4L, 4L, 5L, 5L, 5L 117L、28L、240L、1L、52L、335L、32L、59L、186L、71L、4L、7L、5L、39L、59L、2L、3L、4L、293L、6L、4L、4L、1L 4L, 148L, 221L, 322L, 31L, 170L, 1L, 286L, 162L, 336L, 129L, 138L, 70L, 71L, 125L, 241L, 277L, 3,7L, 3,7L, 3,7L, 7L 69L, 80L, 1L, 243L, 92L, 139L, 149L, 54L, 67L, 262L, 1L, 240L, 78L, 73L, 1L, 187L, 48L, 65L, 65L, 23L, 37L, 93L, 93L, 97L 266L、334L、188L、303L, 96L, 264L, 313L, 184L, 45L, 66L, 105L, 263L, 330L, 184L, 53L, 24L, 96L, 97L, 272L, 331L, 6L, 2L, 263L, 7L, 4L, 8L, 7L 49L、58L、264L、333L、195L、96L、31L、181L、265L、1L、236L、79L、270L、89L、246L、45L、207L、196L、196L、196L、16L 205L, 57L, 168L, 195L, 284L, 94L, 118L, 340L, 82L, 123L, 57L, 73L, 118L, 58L, 227L, 18L, 51L, 51L, 2L, 6L, 6L, 6L, 82L 67L、114L、234L、1L、15L、201L、163L、42L、72L、47L、10L、66L、106L、224L、17L、189L、44L、204L、204L、204L、7L、7L、7L 14L, 190L, 30L, 199L, 161L, 47L, 71L, 52L, 276L, 32L, 199L, 161L, 48L, 73L, 46L, 70L, 103L, 23,7L, 7,4L, 7,7L, 4L, 4L, 4L 23L, 1L, 66L, 338L, 242L, 155L, 72L, 249L, 57L, 80L, 94L, 225L, 341L, 104L, 1L, 116L, 44L, 5L, 2L, 6L, 6L, 6L, 299 46L，278L, 325L, 57L, 314L, 48L, 108L, 44L, 50L, 59L, 1L, 289L, 49L, 42L, 295L, 53L, 304L, 3L, 49L, 4L, 4L, 4L, 4L, 5L 129L、80L、82L、158L、126L、45L、79L、65L、344L、258L、106L、81L、75L、95L、4L、144L、140L、25L、29L、9L、7L 312L、1L、27L、238L、76L、70L、119L、115L、69L、305L、1L、318L、139L、187L、84L、67L、150L、13、2、7、3、7、1L 1L、122L、254L、28L、5L、4L、4L、4L、6L、156L、247L、88L、248L、81L、78L、42L、258L、87L、165L、4L、8L、7L、7L 108L、102L、48L、74L、102L、223L、103L、48L、5L、5L、67L、98L、226L、104L、57L、4L、3L、3L、2L、2L、4L、37L、2L、8L 4L、4L、4L、78L、94L、234L、103L、2L、26L、3L、3L、4L、4L、3L、3L、60L、98L、84L、218L、11L、1、5、15L 4L、65L、112L、311L、216L、146L、1L、131L、217L、55L, 302L, 60L, 202L, 66L, 56L, 167L, 79L, 179L, 142L, 2L, 54L, 145L, 1L, 196L, 60L, 70L, 13,4L, 7L, 7L, 7L, 7L 83L、44L、66L、140L、44L、83L、337L、1L、52L、319L、1L、47L、62L、50L、234L、81L、57L、254L、6、5、2L、56L、319L 121L, 234L, 77L, 51L, 241L, 49L, 63L, 44L, 234L, 81L, 54L, 250L, 2L, 1L, 153L, 338L, 107L, 6,10L, 10L, 10L, 10L, 5L, 10L, 234L, 81L 194L, 160L, 338L, 112L, 139L, 3L, 68L, 2L, 65L, 130L, 49L, 139L, 1L, 50L, 310L, 76L, 279L, 141L, 2L, 2L, 2L, 2L, 14L, 11L, 1L, 130L 84L, 198L, 43L, 54L, 298L, 268L, 26L, 208L, 49L, 51L, 297L, 226L, 92L, 199L, 42L, 54L, 299L, 216L, 8L, 8L, 296L, 8L, 8L, 8L 203L, 43L, 58L, 299L, 267L, 288L, 25L, 183L, 42L, 315L, 92L, 199L, 32L, 56L, 300L, 1L, 105L, 90,4L, 7L, 40L, 4L, 703L 94L、56L、133L, 136L, 72L, 67L, 67L, 115L, 244L, 174L, 112L, 84L, 68L, 143L, 240L, 1L, 220L, 147L, 209L, 1L, 17, 1L, 3, 15L, 1L, 15L 139L, 111L, 55L, 1L, 102L, 51L, 80L, 208L, 241L, 70L, 96L, 80L, 259L, 103L, 70L, 223L, 326L, 25L, 53,57L, 55L, 52L, 57L, 52L 105L, 76L, 53L, 54L, 83L, 84L, 247L, 91L, 68L, 106L, 30L, 324L, 59L, 65L, 296L, 79L, 20L, 71L, 5L, 5L, 5L, 5L 217L、247L、83L、75L、2L、78L、242L、192L、249L、56L、77L、99L、82L、75L、65L、241L、6L、63L、80L、19L、19L、19L 1L、14L、222L、71L、74L、98L、215L、325L、282L、117L、325L、226L、97L、91L、92L、57L、72L、246L、120L、37L、117L 217L, 53L, 70L, 93L, 242L, 329L, 43L, 92L, 104L, 127L, 50L, 306L, 328L, 256L, 76L, 49L, 280L, 20L, 4L, 4L, 4L, 4L, 4L 125L),.Label = c("#VALUE!", "0,1", "0,2", "0,3", "0,4", "0,5", "0,6", "0, 8", "1,0", "1,3", "10,1", "10,2", "10,3", "10,4", "10,5", "10,8" , "10,9", "1023,7", "107,5", "108,5", "108,9", "109,2", "11,0", "11,1", " 11,2", "11,3", "11,4", "11,5", "11,6", "11,7", "11,8", "11,9", "110, 1", "110,2", "110,4", "110,7", "110,8", "110,9", "111,1", "115,8", "12,0" , "12,1", "12,2", "12,3", "12,4", "12,5", "12,6", "12,7", "12,8", "12,9", "13,0", "13,1", "13,2", "13,3" , "13,4", "13,5", "13,6", "13,7", "13,8", "13,9", "132,9", "133,8", " 133,9", "138,1", "14,0", "14,1", "14,2", "14,3", "14,4", "14,5", "14, 6", "14,7", "14,8", "14,9", "15,0", "15,1", "15,2", "15,3", "15,4" , "15,5", "15,6", "15,7", "15,8", "15,9", "156,1", "1569,2", "157,3", " 157,6", "158,5", "16,0", "16,1", "16,2", "16,3", "16,4", "16,5", "16,6", "16,7", "16,8", "16,9", "162,4", " 165,6", "17,0", "17,1", "17,2", "17,3", "17,4", "17,5", "17,6", "17, 7", "17,8", "17,9", "18,0", "18,2", "18,3", "18,4", "18,5", "18,6" , "18,7", "18,8", "18,9", "180,9", "181,4", "19,0", "19,1", "19,3", " 19,4", "19,5", "19,6", "19,7", "19,8", "19,9", "2,1", "2,3", "2, 5", "2,7", "2,8", "20,0", "20,1", "20,3", "20,5", "20,7", "208,1", "21,0", "21,1", "21,3", "21,5", "21,6" , "21,8", "2101,8", "22,0", "22,1", "22,4", "22,5", "22,6", "225,8", " 23,1", "23,2", "23,3", "23,6", "23,9", "24,3", "24,9", "25,3", "25, 4", "253,7", "254,9", "255,3", "26,9", "27,7", "277,6", "278,9", "279,3" , "28,0", "288,3", "29,6", "297,3", "299,6", "3,2", "3,3", "3,8", " 30,3", "303,8", "32,1", "32,4", "32,5", "32,6", "32,7", "32,9", "322,0", "322,2", "326,4", "326,7", "328,9" , "329,4", "33,1", "33,2", "33,3", "33,4", "33,5", "33,6", "33,7", " 33,8", "33,9", "331,4", "34,0", "34,4", "34,5", "34,7", "34,9", "35, 0", "35,3", "35,5", "35,6", "35,7", "35,8", "35,9", "36,0", "36,1" , "36,2", "36,3", "36,4", "36,5", "36,6", "36,7", "36,8", "36,9", " 37,0", "37,1", "37,2", "37,3", "37,4", "37,5", "37,6", "37,8", "37,9", "370,8", "375,6", "38,0", "38,1", " 38,2", "38,3", "38,4", "38,5", "38,6", "38,7", "38,8", "38,9", "39, 0", "39,1", "39,2", "39,3", "39,4", "39,6", "39,7", "39,8", "39,9" , "396,2", "40,1", "40,2", "40,3", "40,7", "40,9", "41,3", "41,4", " 41,6", "41,7", "41,8", "41,9", "42,7", "42,8", "421,0", "43,5", "43, 7", "433,0", "44,2", "446,1", "448,9","449,3", "45,4", "45,8", "47,7", "472,8", "49,2", "492,3", "494,9", "497" ,9", "507,6", "520,8", "54,4", "541,6", "575,4", "577,4", "6,6", "6,8" ", "60,0", "61,2", "61,4", "61,5", "61,6", "61,7", "61,9", "619,1", “62,3”、“62,9”、“63,0”、“63,5”、“64,0”、“64,1”、“64,6”、“642,8”、“646” ,2", "65,8", "663,5", "666,2", "671,6", "7,2", "7,8", "708,7", "711,6" ", "8,1", "8,2", "8,3", "8,5","8,7", "8,8", "8,9", "804,0", "829,0", "856,0", "87,0", "87,4", "87" ,5", "88,1", "88,3", "9,0", "9,1", "9,3", "9,5", "9,7", "9,8" ", "9,9", "90,9", "928,2", "975,8"), class = "factor")), .Names = "HOURS.at.sea", class = "data .frame", row.names = c(NA, -913L))2", "975,8"), class = "factor")), .Names = "HOURS.at.sea", class = "data.frame", row.names = c(NA, -913L))2", "975,8"), class = "factor")), .Names = "HOURS.at.sea", class = "data.frame", row.names = c(NA, -913L))
如果逗号是千位分隔符，这是用户将格式化的 Excel 电子表格保存为 *.csv 然后尝试将其导入 R 时的常见问题，那么您将遇到两个问题。R 中的数字中不允许使用逗号（或者它们被解释为小数点 - 取决于您的语言环境设置），因此，例如as.numeric("1,000")将返回NA，而不是 1000。您必须摆脱逗号并将因子转换为数字。
a <- factor(c("10","20","30","40","50"))
as.numeric(a) # returns the factor codes!!
# [1] 1 2 3 4 5
as.numeric(as.character(a)) # returns the factor levels, as numeric
# [1] 10 20 30 40 50
b <- factor(c(10,20,30,40,50))
as.numeric(b) # returns the factor codes!!
# [1] 1 2 3 4 5
c <- factor(c("1,000","2,000","3,000","4,000","5,000"))
as.numeric(c) # returns the factor codes
# [1] 1 2 3 4 5
as.numeric(as.character(c)) # returns NA - commas are NOT allowed in numbers in R
# [1] NA NA NA NA NA
# Warning message:
# NAs introduced by coercion
as.numeric(gsub(",","",c,fixed=TRUE))
# [1] 1000 2000 3000 4000 5000
在最后一行，gsub(",","",c,fixed=TRUE)只删除逗号。
编辑 正如@CarlWitthoft 在评论中指出的那样，如果逗号是小数点分隔符，则可以使用以下方法导入数据：
df <- read.csv("mydata.csv", dec=",")
这样以后就可以避免很多问题了。鉴于您在问题中提供的（已导入的）数据集，这将解决它：
datatest$HOURS.at.sea <- as.numeric(gsub(",",".",datatest$HOURS.at.sea,fixed=TRUE))
这将替换","用"."。由于gsub(...)返回的是字符向量，而不是因子，因此您可以as.numeric(...)直接使用它。请注意，您仍然会得到一些NAs，因为某些行具有"#VALUE!"- 看起来像 Excel 转储。