r - 对向量中的重复项进行排序和评估

Question

我正在尝试创建一个变量，用于标识向量中的字符串是第一次出现、前三名还是超过三个。例如:

在下面的数据集中，我有姓名(会有更多姓名)、文本和一个 dup 变量。我希望 dup 变量能够识别文本是第一次出现(来源)，它是否在前三个出现(FirstThree)之内，或者它出现的次数是否超过三次(MoreThanThree)。我还需要为每个人做这件事……但我想我可以弄清楚那部分。在此先感谢您的帮助!

name =c("T","T","T","T","T","T","T","T","T","T")
text =c("a","b","a","a","b","c","a","a","b","a")
dup =c("origin","origin","FirstThree","FirstThree","FirstThree","origin","MoreThanThree","MoreThanThree","FirstThree","MoreThanThree")
dfA = data.frame(name,text,dup)

 name text           dup
1     T    a        origin
2     T    b        origin
3     T    a    FirstThree
4     T    a    FirstThree
5     T    b    FirstThree
6     T    c        origin
7     T    a MoreThenThree
8     T    a MoreThenThree
9     T    b    FirstThree
10    T    a MoreThenThree

Answer 1

您可以使用 data.table::rowid带两个 ifelse检查

dfA[, ict := {
        r <- rowid(text)
        ifelse(r == 1, 'origin', 
        ifelse(r <= 3, 'FirstThree', 
               'MoreThanThree'))}
    , by = name]

dfA
#     name text           dup           ict
#  1:    T    a        origin        origin
#  2:    T    b        origin        origin
#  3:    T    a    FirstThree    FirstThree
#  4:    T    a    FirstThree    FirstThree
#  5:    T    b    FirstThree    FirstThree
#  6:    T    c        origin        origin
#  7:    T    a MoreThanThree MoreThanThree
#  8:    T    a MoreThanThree MoreThanThree
#  9:    T    b    FirstThree    FirstThree
# 10:    T    a MoreThanThree MoreThanThree

您也可以使用 cut .唯一的区别是这产生了一个因素而不是性格。如果您有 3 个以上的类别，可能会有用

dfA[, ict := cut(rowid(text), c(0, 1, 3, Inf), 
                 labels = c('origin', 'FirstThree', 'MoreThanThree'))
    , by = name]