将 R 中的 2 列合并为其中之一

Question

我对 R 一无所知，我有一个包含 2 列的 data.frame，它们都是关于动物的性别，但其中一个有一些更正，另一个没有。

我想要的 data.frame 是这样的：

    id  sex  father mother birth.date  farm
    0    1    john   ray   05/06/94     1
    1    1    doug   ana   18/02/93     NA
    2    2    bryan  kim   21/03/00     3

但我通过在其他 2 个 data.frames 上使用合并得到了这个 data.frame

  id sex.x father mother birth.date sex.y farm
    0    2    john   ray    05/06/94    1     1
    1    1    doug   ana    18/02/93    NA    NA
    2    2    bryan  kim    21/03/00    2     3

data.frame 1 或 Animals（某些动物的性别错误）

 id sex father mother birth.date
  0  2   john   ray    05/06/94
  1  1   doug   ana    18/02/93
  2  2   bryan  kim    21/03/00

data.frame 2 或 Farm（具有正确的性别）：

 id farm sex
  0  1    1
  2  3    2

我使用的代码是：Animals_Farm <- merge(Animals , Farm, by="id", all.x=TRUE)

我需要将 2 个性别列合并为一个，优先考虑 sex.y。我该怎么做？

Answer 1

如果我正确理解了您的示例，您的情况类似于我根据merge 函数的示例在下面显示的情况。

> (authors <- data.frame(
      surname = I(c("Tukey", "Venables", "Tierney", "Ripley", "McNeil")),
      nationality = c("US", "Australia", "US", "UK", "Australia"),
      deceased = c("yes", rep("no", 3), "yes")))

   surname nationality deceased
1    Tukey          US      yes
2 Venables   Australia       no
3  Tierney          US       no
4   Ripley          UK       no
5   McNeil   Australia      yes

> (books <- data.frame(
      name = I(c("Tukey", "Venables", "Tierney",
                 "Ripley", "Ripley", "McNeil", "R Core")),
      title = c("Exploratory Data Analysis",
                "Modern Applied Statistics ...", "LISP-STAT",
                "Spatial Statistics", "Stochastic Simulation",
                "Interactive Data Analysis",
                "An Introduction to R"),
      deceased = c("yes", rep("no", 6))))

      name                         title deceased
1    Tukey     Exploratory Data Analysis      yes
2 Venables Modern Applied Statistics ...       no
3  Tierney                     LISP-STAT       no
4   Ripley            Spatial Statistics       no
5   Ripley         Stochastic Simulation       no
6   McNeil     Interactive Data Analysis       no
7   R Core          An Introduction to R       no

> (m1 <- merge(authors, books, by.x = "surname", by.y = "name"))

   surname nationality deceased.x                         title deceased.y
1   McNeil   Australia        yes     Interactive Data Analysis         no
2   Ripley          UK         no            Spatial Statistics         no
3   Ripley          UK         no         Stochastic Simulation         no
4  Tierney          US         no                     LISP-STAT         no
5    Tukey          US        yes     Exploratory Data Analysis        yes
6 Venables   Australia         no Modern Applied Statistics ...         no

authors 可能代表您的第一个数据框，books 您的第二个数据框，deceased 可能是两个数据框内的值，但仅在其中一个数据框内是最新的 (authors)。

仅包含正确值 deceased 的最简单方法是从合并中排除不正确的值。

> (m2 <- merge(authors, books[names(books) != "deceased"], 
               by.x = "surname", by.y = "name"))

   surname nationality deceased                         title
1   McNeil   Australia      yes     Interactive Data Analysis
2   Ripley          UK       no            Spatial Statistics
3   Ripley          UK       no         Stochastic Simulation
4  Tierney          US       no                     LISP-STAT
5    Tukey          US      yes     Exploratory Data Analysis
6 Venables   Australia       no Modern Applied Statistics ...

代码行books[names(books) != "deceased"] 只是对数据框books 进行子集化，以删除deceased 列，在最终合并中仅从authors 中留下正确的deceased 列。