按日期范围联接表

Question

我正在寻找一种简单的方法来按日期范围联接两个表。一个表包含确切的日期，另一个表包含两个标识时间段开始和结束的变量。如果第一个表中的日期与第二个表中的范围不符，则需要加入表。

data1 <- data.table(date = c('2010-01-21', '2010-01-25', '2010-02-02', '2010-02-09'),
                name = c('id1','id2','id3','id4'))


data2 <- data.table(beginning=c('2010-01-15', '2010-01-23', '2010-01-30', '2010-02-05'), 
                ending = c('2010-01-22','2010-01-29','2010-02-04','2010-02-13'),
                class = c(1,2,3,4))

result <- data.table(date = c('2010-01-21', '2010-01-25', '2010-02-02', '2010-02-09'),
                 beginning=c('2010-01-15', '2010-01-23', '2010-01-30', '2010-02-05'), 
                 ending = c('2010-01-22','2010-01-29','2010-02-04','2010-02-13'),
                 name = c('id1','id2','id3','id4'),
                 class = c(1,2,3,4))

有什么帮助吗？我发现了一些困难的例子，但由于格式的原因，它们甚至无法处理我的数据。我需要类似的东西：

select * from data1
left join
select * from data2
where data2.beginning <= data1.date <= data2.ending

谢谢

Answer 1

我知道以下内容看起来很可怕，但这是我想出的。最好使用“ sqldf”包（请参见下文）。

library(data.table)
data1 <- data.table(date = c('2010-01-21', '2010-01-25', '2010-02-02', '2010-02-09'),
                    name = c('id1','id2','id3','id4'))


data2 <- data.table(beginning=c('2010-01-15', '2010-01-23', '2010-01-30', '2010-02-05'), 
                    ending = c('2010-01-22','2010-01-29','2010-02-04','2010-02-13'),
                    class = c(1,2,3,4))

result <- cbind(data1,"beginning"=sapply(1:nrow(data2),function(x) data2$beginning[data2$beginning[x]<data1$date & data2$ending[x]>data1$date]),
            "ending"=sapply(1:nrow(data2),function(x) data2$ending[data2$beginning[x]<data1$date & data2$ending[x]>data1$date]),
            "class"=sapply(1:nrow(data2),function(x) data2$class[data2$beginning[x]<data1$date & data2$ending[x]>data1$date]))

使用软件包sqldf：

library(sqldf)
result = sqldf("select * from data1
                left join data2
                on data1.date between data2.beginning and data2.ending")