R在多个标准上交叉data.frame

Question

我试图基于多个条件上的两个data.frames的交集来填充二进制向量.

我有代码工作,但我觉得只是为了得到二进制矢量是内存过多.

当我将我的代码应用于我的完整数据(40毫米+行)时.我开始有记忆问题.

是否有更简单的方法来生成向量？

以下是一些样本数据(例如,子样本仅包括完整样本中的obs.):

ob1_1 <- as.data.frame(cbind(c(1999),c("111","222","666","777")),stringsAsFactors=FALSE)
ob2_1 <- as.data.frame(cbind(c(2000),c("111","333","555","777")),stringsAsFactors=FALSE)
ob3_1 <- as.data.frame(cbind(c(2001),c("111","222","333","777")),stringsAsFactors=FALSE)
ob4_1 <- as.data.frame(cbind(c(2002),c("111","444","555","777")),stringsAsFactors=FALSE)

full_sample <-  rbind(ob1_1,ob2_1,ob3_1,ob4_1)
colnames(full_sample) <- c("yr","ID")

ob1_2 <- as.data.frame(cbind(c(1999),c("111","222","777")),stringsAsFactors=FALSE)
ob2_2 <- as.data.frame(cbind(c(2000),c("333")),stringsAsFactors=FALSE)
ob3_2 <- as.data.frame(cbind(c(2001),c("888")),stringsAsFactors=FALSE)
ob4_2 <- as.data.frame(cbind(c(2002),c("111","444","555","777")),stringsAsFactors=FALSE)

sub_sample <-  rbind(ob1_2,ob2_2,ob3_2,ob4_2)
colnames(sub_sample) <- c("yr","ID")

这是我的工作代码:

q_intersect <- ""
q_intersect <- paste(q_intersect , "select       a.yr, a.ID       ", sep=" ")
q_intersect <- paste(q_intersect , "from         full_sample a  ", sep=" ")
q_intersect <- paste(q_intersect , "intersect                     ", sep=" ")
q_intersect <- paste(q_intersect , "select       b.yr, b.ID       ", sep=" ")
q_intersect <- paste(q_intersect , "from         sub_sample b  ", sep=" ")
q_intersect <- trim(gsub(" {2,}", " ", q_intersect ))

intersect_temp <- cbind(sqldf(q_intersect ),1)
colnames(intersect_temp ) <- c("yr","ID","in_both")

q_expand <- ""
q_expand <- paste(q_expand , "select       in_both            ", sep=" ")
q_expand <- paste(q_expand , "from         full_sample a      ", sep=" ")
q_expand <- paste(q_expand , "left join    intersect_temp  b  ", sep=" ")
q_expand <- paste(q_expand , "on           a.yr=b.yr          ", sep=" ")
q_expand <- paste(q_expand , "and          a.ID=b.ID          ", sep=" ")
q_expand <- trim(gsub(" {2,}", " ", q_expand ))

solution <- as.integer(sqldf(q_expand)[,1])
solution [is.na(solution )] <- 0 

提前感谢您的帮助!

Answer 1

目前尚不完全清楚您想要完成什么，但我相信这样的事情会简单得多。

library(data.table)
fullDT <- data.table(full_sample, key=c("yr", "ID"))
subDT  <- data.table(sub_sample,  key=c("yr", "ID"))

fullDT[ , intersect := 0L]
fullDT[subDT, intersect := 1, nomatch=0]

这个想法是将key每个列设置data.table为要相交的列。当您调用时，full[sub], nomatch=0]您会获得内部连接，我们仅将这些值设置为1; 内连接中未识别的值保留为0，如前面行中设置的那样。

fullDT
#        yr  ID intersect
#   1: 1999 111         1
#   2: 1999 222         1
#   3: 1999 666         0
#   4: 1999 777         1
#   5: 2000 111         0
#   6: 2000 333         1
#   7: 2000 555         0
#   8: 2000 777         0
#   9: 2001 111         0
#  10: 2001 222         0
#  11: 2001 333         0
#  12: 2001 777         0
#  13: 2002 111         1
#  14: 2002 444         1
#  15: 2002 555         1
#  16: 2002 777         1