2017年3月6日
special-symbols in package(data.table)
摘要： The general form of data.table syntax is: .SD , .SDcols , .N 等 .SD stands for something like "Subset of Data.table". There's no significance to the in 阅读全文
posted @ 2017-03-06 17:34 Emily_zhu 阅读(255) 评论(0) 推荐(0) 编辑
R&SQL合并记录并去重
摘要： data: have <- data.frame(ID=paste0("id", c(101, 102, 102, 103, 103, 104, 105, 105)), info1=c("one", "twoA", "twoB", "threeA", "threeB", "four", "five" 阅读全文
posted @ 2017-03-06 12:16 Emily_zhu 阅读(1402) 评论(0) 推荐(0) 编辑