Question

我试图从myDF2替换myDF1中的值，其中行匹配列＆＃34; studyno＆＃34; ，但我到目前为止找到的解决方案并不适用好像给了我想要的输出。

以下是data.frames：

myDF1 <- structure(list(studyno = c("J1000/9", "J1000/9", "J1000/9", "J1000/9", 
"J1000/9", "J1000/9"), date = structure(c(17123, 17127, 17135, 
17144, 17148, 17155), class = "Date"), pf_mcl = c(NA_integer_, 
NA_integer_, NA_integer_, NA_integer_, NA_integer_, NA_integer_
), year = c(2016, 2016, 2016, 2016, 2016, 2016)), .Names = c("studyno", 
"date", "pf_mcl", "year"), row.names = c(NA, 6L), class = "data.frame")

myDF2 <- structure(list(studyno = c("J740/4", "J1000/9", "J895/7", "J931/6", 
"J609/1", "J941/3"), pf_mcl = c(0L, 0L, 0L, 0L, 0L, 0L)), .Names = c("studyno", 
"pf_mcl"), row.names = c(NA, 6L), class = "data.frame")

我试过的一个似乎有用的解决方案如下所示，但是，我发现myDF1中的任何值都被移除了。

myDF1$pf_mcl <- myDF2$pf_mcl[match(myDF1$studyno, myDF2$studyno)]

Answer 1

# Merge myDF1 & myDF2 by the "studyno", keeping all the rows in myDF1
agg_df = merge(myDF1, myDF2, "studyno", all.x=TRUE)
# Populate pf_mcl in the merged dataframe by using pf_mcl in myDF2 if it is available. Otherwise, use pf_mcl from myDF1
# is missing in myDF1
agg_df$pf_mcl = ifelse(is.na(agg_df$pf_mcl.y), agg_df$pf_mcl.x, agg_df$pf_mcl.y)
myDF1 = agg_df[, names(myDF1)]

R - 基于行匹配，使用来自另一个数据帧的值填充一个数据帧

1 个答案: