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写入函数以计算向量中NA值的数量,同时忽略指定的索引

na vector function r

1

Max Lester · 技术社区 · 7 年前

NA 向量中的值(在第一个参数中指定),在进行计数时也将忽略某些索引(在第二个参数中指定)。

例如,如果我有 x = c(1,NA,3,4,NA,6,NA,8,9)

我想给我们一个函数,比如 countNA(vector = x, ignore = c(5,7)) 并返回计数1(函数被告知忽略 x[5] 和 x[7]

countNA.2 = function(x, ignore){ 
    #define a function with arguments "x" (vector to be searched for NAs) 
    #and "ignore" vector indices to be ignored if NA
    count = c() #define empty vector to hold the counts of na in vector x
    t = c(1:9) #define a reference vector to represent possible indicies
    #(max vector length is 9)
    for (q in t){ #loop through our possible vector indicies
        ifelse(q %in% ignore, count[q] = 0, count[q] = is.na(x[q])) 
        #if index is in ignore vector, then set count[q] = 0 
        #else, set count[q] = TRUE for NA and FALSE otherwise
    }
    numoccurrences = sum(count) #after we're done, sum our count vector
    return(numoccurrences) #return
}

1 回复 | 直到 4 年前

1

thelatemail 7 年前

只需从向量中移除值,然后取 sum 属于 is.na :

cntNA <- function(x, ignore) sum(is.na(x[-(ignore)]))
cntNA(x, ignore=c(5,7))
#[1] 1

ignore if/else 条件:

cntNA <- function(x, ignore=NULL) {
  if (is.null(ignore)) {
    sum(is.na(x))
  } else
  {
    sum(is.na(x[-(ignore)]))
  }
}

cntNA(x)
#[1] 3

cntNA(x, ignore=c(5,7))
#[1] 1