使用 ordered() 对 R 中的因子水平进行排序时，观察结果变为 NA

Question

你好有一个包含 4 个变量的纵向数据框 p，如下所示：

> head(p)
    date.1           County.x providers beds    price
1 Jan/2011              essex       258 5545 251593.4
2 Jan/2011 greater manchester       108 3259 152987.7
3 Jan/2011               kent       301 7191 231985.7
4 Jan/2011      tyne and wear       103 2649 143196.6
5 Jan/2011      west midlands       262 6819 149323.9
6 Jan/2012              essex         2   27 231398.5

我的变量结构如下：

'data.frame':   259 obs. of  5 variables:
 $ date.1   : Factor w/ 66 levels "Apr/2011","Apr/2012",..: 23 23 23 23 23 24 24 24 25 25 ...
 $ County.x : Factor w/ 73 levels "avon","bedfordshire",..: 22 24 32 65 67 22 32 67 22 32 ...
 $ providers: int  258 108 301 103 262 2 9 2 1 1 ...
 $ beds     : int  5545 3259 7191 2649 6819 27 185 24 70 13 ...
 $ price    : num  251593 152988 231986 143197 149324 ...

我想按时间顺序date.1。在应用 ordered() 之前，此变量不包含 NA 观察值。

> summary(is.na(p$date.1))
   Mode   FALSE    NA's 
logical     259       0

但是，一旦我应用我的函数来排序对应于 date.1 的级别：

p$date.1 = with(p, ordered(date.1, levels = c("Jun/2010", "Jul/2010",
                               "Aug/2010", "Sep/2010", "Oct/2010", "Nov/2010", "Dec/2010", "Jan/2011", "Feb/2011",
                                                          "Mar/2011","Apr/2011", "May/2011", "Jun/2011", "Jul/2011", "Aug/2011", "Sep/2011",
                                                          "Oct/2011", "Nov/2011", "Dec/2011" ,"Jan/2012", "Feb/2012" ,"Mar/2012" ,"Apr/2012",
                                                          "May/2012", "Jun/2012", "Jul/2012", "Aug/2012", "Sep/2012", "Oct/2012", "Nov/2012",
                                                          "Dec/2012", "Jan/2013", "Feb/2013", "Mar/2013", "Apr/2013", "May/2013",
                                                          "Jun/2013", "Jul/2013", "Aug/2013", "Sep/2013", "Oct/2013", "Nov/2013", 
                                                          "Dec/2013", "Jan/2014",
                                                          "Feb/2014", "Mar/2014", "Apr/2014", "May/2014", "Jun/2014", "Jul/2014" ,"Aug/2014",
                                                          "Sep/2014", "Oct/2014", "Nov/2014", "Dec/2014", "Jan/2015", "Feb/2015", "Mar/2015",
                                                          "Apr/2015","May/2015", "Jun/2015" ,"Jul/2015" ,"Aug/2015", "Sep/2015", "Oct/2015",
                                                          "Nov/2015")))

看来我漏掉了一些观察结果。

> summary(is.na(p$date.1))
   Mode   FALSE    TRUE    NA's 
logical     250       9       0

有人在使用ordered()时遇到过这个问题吗？或者，是否有任何其他可能的解决方案来按时间顺序对我的观察结果进行分组？

Answer 1

您的 p$date.1 可能有一个不符合任何级别。试试这个 ord.mon 作为关卡。

ord.mon <- do.call(paste, c(expand.grid(month.abb, 2010:2015), sep = "/"))

那你可以试试看这两者有没有不匹配的地方

p$date.1 %in% ord.mon

最后，您还可以在将 date.1 列转换为 Date 之后对数据框进行排序（注意您必须事先添加实际日期）

p <- p[order(as.Date(paste0("01/", p$date.1), "%d/%b/%Y")), ]

使用 ordered() 对 R 中的因子水平进行排序时，观察结果变为 NA

Observations becoming NA when ordering levels of factors in R with ordered()

r

factors