r - R 中 `str` 报告的第二列是什么，该列中的 `atomic` 是什么意思？

Question

使用 str(survey_OM)在我的数据框中表示我所有的数值数据都是 atomic .如果我使用 class(survey_OM$perc.OM)它返回 numeric .

一直以为str的第二栏显示了数据的类，但看起来并不那么简单......所以我的问题是:

str的第二列是什么报告？

什么是atomic以及它与 numeric 有何不同?

为什么在这种情况下数据会显示为 atomic而不是 num或 int ?

谢谢你。 dput(head(survey_OM, 20))提供:

> dput(head(survey_OM, 20))
  structure(list(lake = structure(c(3L, 3L, 3L, 3L, 3L, 3L, 3L, 
  3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L), .Label = c("E-2", 
  "E-4", "E pond", "EX 1", "GTH 110", "GTH 112", "GTH 114", "GTH 156", 
  "GTH 91", "GTH 98", "N-1", "NE-10", "NE-11", "NE-3", "NE-8", 
  "NE-9", "NE-9b", "S-10", "S-11", "S-3", "S-6", "S-7"), class = "factor"), 
  date = structure(c(2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
  2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("2007/06/15", 
  "2007/06/18", "2007/06/19", "2007/06/20", "2007/06/21", "2007/06/27", 
  "2007/06/29", "2007/07/07", "2007/07/19", "2007/07/20", "2008/07/26", 
  "2008/07/30", "2008/08/04", "2008/08/06"), class = "factor"), 
  depth = structure(c(2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
  2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("E", 
  "epi", "H", "hypo"), class = "factor"), 
  depth.m = structure(c(6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L), .Label = c("", "10.9", "12.9", "1.5", "2", 
  "2.1", "2.2", "2.3", "2.4", "2.5", "2.6", "2.7", "3", "3.1", 
  "3.5", "4", "4.2", "4.8", "4.9", "5", "5.1", "5.5", "6", 
  "6.5", "7", "7.2", "9.9", "not recorded"), class = "factor"), 
  rep = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
  2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("A", 
  "B", "C"), class = "factor"), 
  sed = c(0L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 0L, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L), 
  notes = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = c("", 
  "col on SE side", "lg snail shell", "not collected", "very hard sediments"
  ), class = "factor"), 
  dry.mass = c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), 
  perc.OM = c(47.1300248455119, 47.4260808104607, 47.7349307375515, 46.4501104675465, 44.1513415737111, 43.5608499678045, 42.9921259842519, 42.2674677347574, 39.6643311064039, 
  39.0968130690949, 46.7768514928267, 46.9211608642763, 46.7877013177158, 
  47.0709930313588, 44.3241152581706, 43.7905468025952, 41.706074101281, 
  36.5061097383474, 37.4329041152142, 37.7757939038389)), .Names = c("lake", 
  "date", "depth", "depth.m", "rep", "sed", "notes", "dry.mass", 
  "perc.OM"), comment = c("working data frame of the sediment char from the 2007 sed    survey       created:", "Wed Apr 27 14:23:33 2011"), row.names = c(NA, 20L), class = "data.frame")

以及 str(survey_OM) 的完整输出是:

> str(survey_OM)
'data.frame':   780 obs. of  9 variables:
 $ lake    : Factor w/ 22 levels "E-2","E-4","E pond",..: 3 3 3 3 3 3 3 3 3 3 ...
  ..- attr(*, "comment")= chr "names of the lakes"
 $ date    : Factor w/ 14 levels "2007/06/15","2007/06/18",..: 2 2 2 2 2 2 2 2 2 2 ...
  ..- attr(*, "comment")= chr "date that the cores were collected"
 $ depth   : Factor w/ 4 levels "E","epi","H",..: 2 2 2 2 2 2 2 2 2 2 ...
  ..- attr(*, "comment")= chr "relative depth ID; epi = shallowest corable Z, hypo =   deepest Z, S, M, D = shallow, med, deep"
 $ depth.m : Factor w/ 28 levels "","10.9","12.9",..: 6 6 6 6 6 6 6 6 6 6 ...
  ..- attr(*, "comment")= chr "depth that core was collected in m"
 $ rep     : Factor w/ 3 levels "A","B","C": 1 1 1 1 1 1 1 1 1 1 ...
  ..- attr(*, "comment")= chr "replicate ID for core"
 $ sed     : atomic  0 1 2 3 4 5 6 7 8 9 ...
  ..- attr(*, "comment")= chr "depth of sample from sed/water interface in cm"
 $ notes   : Factor w/ 5 levels "","col on SE side",..: 1 1 1 1 1 1 1 1 1 1 ...
  ..- attr(*, "comment")= chr "comments on sample"
 $ dry.mass: atomic  0 0 0 0 0 0 0 0 0 0 ...
  ..- attr(*, "comment")= chr "dry mass of the sediment at that sed Z in g/m^2"
 $ perc.OM : atomic  47.1 47.4 47.7 46.5 44.2 ...
  ..- attr(*, "comment")= chr "percent OM of the samp. based on LOI at 550d C"
 - attr(*, "comment")= chr  "working data frame of the sediment char from the 2007 sed survey created:" "Wed Apr 27 14:23:33 2011"

Answer 1

看着 utils:::str.default ，我们看到我们得到了通常的输出 int , num等，如果以下if声明为真:

if (     is.vector(object) 
     || (is.array(object) && is.atomic(object))
     ||  is.vector(object, mode = "language") 
     || is.vector(object, mode = "symbol")
   )

我们得到 atomic如果这个陈述是错误的(否则它会是 int 、 num 等)。

查看 is.vector 的帮助页面，我们看到它只有在它是一个除了名称之外没有其他属性的向量时才返回真。这是一个数据框，其中 b有一个额外的属性:

d <- data.frame(a=1:4, b=5:8)
attr(d$b, "tmp") <- "surprise!"

并调用 str在它上面给 atomic为 b而不是 int .

> str(d)
'data.frame':   4 obs. of  2 variables:
 $ a: int  1 2 3 4
 $ b: atomic  5 6 7 8
  ..- attr(*, "tmp")= chr "surprise!"

我在你的编辑中看到你的数据框的元素有额外的属性，并且你也得到了关于你的属性的这些额外的行，所以这似乎解释了它。