PROSAGA码农传奇-R-根据R中的四个条件计算两列的值

<div class =“post-text”itemprop =“text”>
  
    让我感到震惊的是你的专栏
     <code>
 "Length", "TNumStat", "TNumLK"
 </code>
     有
     <code>
 ,
 </code>
     代替
     <code>
 .
 </code>
     因此，字符格式不容易被强制转换为数字。
  
   <pre>
 <code>
 TNumStat[c("TNumStat", "TNumLK")] <- 
 lapply(TNumStat[c("TNumStat", "TNumLK")], 
 function(x) as.numeric(gsub(",", ".", x)))

</code>
 </pre>
  
    也许这取决于您的系统区域设置，因此如果适合您，请忽略此步骤。
  
  
    然后，你可以使用
     <code>
 by
 </code>
     申请你的公式。
  
   <pre>
 <code>
 l <- by(TNumStat, TNumStat[c("Cruiseid", "Samplenr", "Species")],
 function(x) cbind(unique(x[1:3]),
 value=with(x, ((mean(TNumLK)/mean(TNumStat))*0.5+0.25)*10)))

</code>
 </pre>
  
    这给你一个列表
     <code>
 rbind
 </code>
     得到结果。
  
   <pre>
 <code>
 TNumStat.new <- do.call(rbind, l)

TNumStat.new
#    Cruiseid Samplenr Species     value
# 6    197502       35     154 148.46288
# 10   197502       36     154  85.14956
# 1    197502       37     154 149.61421
# 12   197502       41     154 174.24600
# 26   197503       53     154 106.86347
# 20   197503       54     154 159.17545
# 16   197503       56     154 131.26698

</code>
 </pre>
  <HR />
  
    的
      
        数据
      
    </强>
  
   <pre>
 <code>
 TNumStat <- structure(list(Cruiseid = c(197502L, 197502L, 197502L, 197502L, 
197502L, 197502L, 197502L, 197502L, 197502L, 197502L, 197502L, 
197502L, 197502L, 197502L, 197502L, 197503L, 197503L, 197503L, 
197503L, 197503L, 197503L, 197503L, 197503L, 197503L, 197503L, 
197503L, 197503L, 197503L, 197503L), Samplenr = c(37L, 37L, 37L, 
37L, 37L, 35L, 35L, 35L, 35L, 36L, 36L, 41L, 41L, 41L, 41L, 56L, 
56L, 56L, 56L, 54L, 54L, 54L, 54L, 54L, 54L, 53L, 53L, 53L, 53L
), Species = c(154L, 154L, 154L, 154L, 154L, 154L, 154L, 154L, 
154L, 154L, 154L, 154L, 154L, 154L, 154L, 154L, 154L, 154L, 154L, 
154L, 154L, 154L, 154L, 154L, 154L, 154L, 154L, 154L, 154L), 
 Age = c(0L, 0L, 2L, 2L, 2L, 0L, 2L, 2L, 2L, 0L, 2L, 0L, 2L, 
 2L, 2L, 0L, 0L, 2L, 2L, 0L, 0L, 0L, 2L, 2L, 2L, 0L, 0L, 0L, 
 0L), Length = structure(c(3L, 8L, 9L, 10L, 11L, 2L, 13L, 
 16L, 17L, 3L, 11L, 8L, 14L, 15L, 18L, 8L, 5L, 9L, 12L, 3L, 
 6L, 7L, 9L, 12L, 16L, 3L, 19L, 1L, 4L), .Label = c("107,5", 
 "112,5", "12,5", "142,5", "147,5", "157,5", "167,5", "17,5", 
 "172,5", "177,5", "182,5", "187,5", "197,5", "202,5", "212,5", 
 "217,5", "232,5", "242,5", "97,5"), class = "factor"), LK = c(2L, 
 3L, 34L, 35L, 36L, 22L, 39L, 43L, 46L, 2L, 36L, 3L, 40L, 
 42L, 48L, 3L, 29L, 34L, 37L, 2L, 31L, 33L, 34L, 37L, 43L, 
 2L, 19L, 21L, 28L), TNumStat = structure(c(16L, 11L, 2L, 
 5L, 9L, 3L, 10L, 10L, 10L, 21L, 19L, 13L, 20L, 12L, 12L, 
 24L, 1L, 6L, 14L, 18L, 4L, 7L, 8L, 15L, 15L, 17L, 22L, 23L, 
 25L), .Label = c("10,30952381", "11,54166667", "11,85654008", 
 "12", "12,0625", "13,19047619", "13,25", "13,85", "2,083333333", 
 "2,109704641", "2,166666667", "2,173913043", "2,260869565", 
 "2,380952381", "2,5", "2,791666667", "2,875536481", "3,35", 
 "3,496503497", "4,347826087", "4,685314685", "4,806866953", 
 "5,622317597", "7,428571429", "8,776824034"), class = "factor"), 
 TNumLK = structure(c(16L, 18L, 11L, 12L, 21L, 8L, 22L, 25L, 
 29L, 24L, 4L, 20L, 5L, 26L, 1L, 6L, 9L, 14L, 23L, 19L, 10L, 
 13L, 15L, 28L, 2L, 17L, 27L, 3L, 7L), .Label = c("104,3478", 
 "107,5", "118,0687", "125,8741", "173,913", "22,28571", "245,7511", 
 "260,8439", "298,9762", "372", "392,4167", "422,1875", "437,25", 
 "448,4762", "470,9", "5,583333", "5,751073", "6,5", "6,7", 
 "6,782609", "75", "82,27848", "88,09524", "9,370629", "90,7173", 
 "91,30435", "91,33047", "92,5", "97,04641"), class = "factor")), class = "data.frame", row.names = c(NA, 
-29L))

</code>
 </pre>
</DIV>