R&SQL合并记录并去重

====================================================================================

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", "five"),
stringsAsFactors=FALSE)
want <- data.frame(ID=paste0("id", c(101:105)),
info1=c("one", "twoA; twoB", "threeA; threeB", "four", "five"),
stringsAsFactors=FALSE)

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 MySQL

SELECT
    user_id,
    COUNT(id) AS freq,
    GROUP_CONCAT(DISTINCT ip SEPARATOR ",") AS ips
FROM
    log_table
GROUP BY
    user_id
ORDER BY
    freq ASC;

====================================================================================

 R&SQL

library(sqldf)

sqldf("
SELECT ID,
GROUP_CONCAT(distinct info1) as info1
FROM have
GROUP BY ID")

注：此种情况没能实现更改间隔符，默认为逗号。

====================================================================================

 R

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require(dplyr)

METHOD1:　　have %>%　　　　group_by(ID) %>%　　　　summarise_each(funs(toString(sort(unique(info1)))))

METHOD2:　　have %>%　　　　group_by(ID) %>%　　　　summarise(name = toString(sort(unique(info1))))

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require(data.table)

METHOD1:　　setDT(have)[, .(info1 = toString(sort(unique(info1)))), by = ID]
METHOD2:　　setDT(have)[ , .(info1 = paste(unique(info1), collapse = ",")),by = ID]

注：paste函数作为其他函数的参数时，不能。例如

aggregate(have[,2], by=list(have$ID), paste(unique(info1)), collapse=";")   × 

aggregate(have[,2], by=list(have$ID), paste, collapse=";")  √

setDT(have)[, lapply(.SD, paste(unique(info1)), collapse = "; "), by = ID]  ×

setDT(have)[, lapply(.SD, paste, collapse = "; "), by = ID]  √

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aggregate(data=have,info1~ID,FUN = function(t) sort(unique(t)))