I have two dataframes:
我有两个dataframes:
df1 <- data.frame(cola = c("dum1", "dum2", "dum3"), colb = c("bum1", "bum2", "bum3"), colc = c("cum1", "cum2", "cum3"))
and:
和:
df2 <- data.frame(cola = c("dum1", "dum2", "dum4"), colb = c("bum1", "bum2", "bum3"))
I need to find the indices of the rows in dataframe df1 in which the columns cola and colb are the same, here it would be row 1 and row 2. I know the inner_join function from the dplyr package but this results in a new dataframe. I just need a vector with the indices. I could do this with which for each column needed but this would be ugly if I need to find common rows based on a large number of columns.
我需要找到dataframe df1中的行索引，其中的列cola和colb是相同的，这里是第1行和第2行。我从dplyr包中知道inner_join函数，但是这会产生一个新的dataframe。我只需要一个带指标的向量。对于需要的每一列，我都可以这样做，但是如果我需要基于大量的列找到公共行，这就太糟糕了。
Any help is much appreciated.
非常感谢您的帮助。
2 个解决方案
#1
3
The more general typical way of solving this would look like:
更一般的解决方法是:
colsToUse <- intersect(colnames(df1), colnames(df2))
match(do.call("paste", df1[, colsToUse]), do.call("paste", df2[, colsToUse]))
[1] 1 2 NA
[1]1 2 NA
#2
0
Just do
只做
which(apply(df1[1:2]==df2,1,prod)==1)
#1
3
The more general typical way of solving this would look like:
更一般的解决方法是:
colsToUse <- intersect(colnames(df1), colnames(df2))
match(do.call("paste", df1[, colsToUse]), do.call("paste", df2[, colsToUse]))
[1] 1 2 NA
[1]1 2 NA
#2
0
Just do
只做
which(apply(df1[1:2]==df2,1,prod)==1)