R - 字符串处理的变异 - 没有得到我希望的行为

Question

我正在尝试在 dplyr 中使用 mutate 来处理字符串，但我没有得到我想要的输出(见下文)，mutate 不是逐行操作，而是获取第一个元素并将其向下填充。我想知道是否有人可以帮助我了解我做错了什么以及如何调整此代码以使其正常工作。

short.idfun = function(longid) 
{
    x      = strsplit(longid,"_")
    y      = x[[1]]
    study  = substr(y[1],8,nchar(y[1]))
    subj   = y[length(y)]
    subj   = substr(subj,regexpr("[^0]",subj),nchar(subj)) #remove leading zeros
    shortid= paste(study,subj,sep="-")
    return(shortid)
}

data = data.frame(test=c("1234567Andy_003_003003","1234567Beth_004_003004","1234567Char_003_003005"),stringsAsFactors=FALSE)
data= mutate(data,shortid=short.idfun(test))
print(data)

#### Below is my output
#                       test   shortid
#1    1234567Andy_003_003003 Andy-3003
#2    1234567Beth_004_003004 Andy-3003
#3    1234567Char_003_003005 Andy-3003

#### This is the behavior I was hoping for
#                       test   shortid
#1    1234567Andy_003_003003 Andy-3003
#2    1234567Beth_004_003004 Beth-3004
#3    1234567Char_003_003005 Char-3005

Answer 1

另一种选择是使用 rowwise():

data %>%
  rowwise() %>% 
  mutate(shortid = short.idfun(test))

给出:

#Source: local data frame [3 x 2]
#Groups: <by row>
#
#                    test   shortid
#                   (chr)     (chr)
#1 1234567Andy_003_003003 Andy-3003
#2 1234567Beth_004_003004 Beth-3004
#3 1234567Char_003_003005 Char-3005