如何在其他列中查找相对分配ids

Question

我有一个玩具例子来解释我想要做的事情：

aski = data.frame(x=c("a","b","c","a","d","d"),y=c("b","a","d","a","b","c"))

我设法为y列分配了唯一的ids，现在的输出如下所示：

aski2 = data.frame(x=c("a","b","c","a","d","d"),y=c("1","2","3","2","1","4"))

正如您所看到的，在col和y中都存在"b“，我们在col中分配了一个id=1，而在col中分配了一个带有id=2的"a”等等。如你所见，这些值也存在于x中.col x的第一个元素是"a“。”a“也在col中，并分配了一个id=2，所以我将为一个in col分配一个id=2，现在我要做的是在col中查找这些值，如果它发生在col中，我会将这个id分配给它。

像一样的

aski3 = data.frame(x=c("2","1","4","2","3","3"),y=c("1","2","3","2","1","4"))

Answer 1

首先，将两列转换为字符向量。然后，收集两列的所有唯一值，作为一个因子的级别使用。

将两列转换为因素，然后转换为数字。

aski = data.frame(x=c("a","b","c","a","d","d"),y=c("b","a","d","a","b","c"))

aski$x <- as.character(aski$x)
aski$y <- as.character(aski$y)

lev <- unique(c(aski$y, aski$x))
aski$x <- factor(aski$x, levels=lev)
aski$y <- factor(aski$y, levels=lev)

aski$x <- as.numeric(aski$x)
aski$y <- as.numeric(aski$y)
aski

Answer 2

不需要创建aski2作为中间程序，一个可能的解决方案是使用match和lapply来获取字母的数字表示：

# create a vector of the unique values in the order
# in which you want them assigned to '1' till '4'
v <- unique(aski$y) 

# convert both columns to integer values with 'match' and 'lapply'
aski[] <- lapply(aski, match, v)

这意味着：

阿斯基x 1 2 1 2 1 2 3 4 4 2 2 5 3 6 3 4

如果要将数字作为字符，则还可以执行以下操作：

aski[] <- lapply(aski, as.character)

Answer 3

来自dplyr的解决方案。首先，我们可以通过vec创建一个向量，将索引和字母之间的关系用unique(aski$y)表示。在这一步之后，您可以使用Jaap的lapply解决方案，也可以使用来自dplyr的mutata_all，如下所示。

# Create the vector showing the relationship of index and letter 
vec <- unique(aski$y)
# View vec
vec
[1] "b" "a" "d" "c"

library(dplyr)

# Modify all columns
aski2 <- aski %>% mutate_all(funs(match(., vec)))
# View the results
aski2
  x y
1 2 1
2 1 2
3 4 3
4 2 2
5 3 1
6 3 4

数据

aski <- data.frame(x = c("a","b","c","a","d","d"),
                   y = c("b","a","d","a","b","c"),
                   stringsAsFactors = FALSE)