R:在同一数据表中合并行,连接某些列

Question

我在R中有我的数据表.我想合并具有相同的行customerID,然后连接其他合并列的元素.

我想离开这个:

   title  author customerID
1 title1 author1          1
2 title2 author2          2
3 title3 author3          1

对此:

           title           author Group.1
1 title1, title3 author1, author3       1
2         title2          author2       2

Answer 1

该aggregate功能应该可以帮助您找到解决方案:

dat = data.frame(title = c("title1", "title2", "title3"),
                 author = c("author1", "author2", "author3"),
                 customerID = c(1, 2, 1))
aggregate(dat[-3], by=list(dat$customerID), c)
#   Group.1 title author
# 1       1  1, 3   1, 3
# 2       2     2      2

或者,只需确保stringsAsFactors = FALSE在创建数据框时添加,然后就可以了.如果您的数据已经被分解,您可以先使用类似的dat[c(1, 2)] = apply(dat[-3], 2, as.character)方法将它们转换为字符,然后:

aggregate(dat[-3], by=list(dat$customerID), c)
#   Group.1          title           author
# 1       1 title1, title3 author1, author3
# 2       2         title2          author2