I'm trying to identify the values in a data frame that do not match, but can't figure out how to do this.
我正在尝试识别数据框中不匹配的值，但无法弄清楚如何执行此操作。
# make data frame
a <- data.frame( x = c(1,2,3,4))
b <- data.frame( y = c(1,2,3,4,5,6))
# select only values from b that are not in 'a'
# attempt 1:
results1 <- b$y[ !a$x ]
# attempt 2:
results2 <- b[b$y != a$x,]
If a = c(1,2,3) this works, as a is a multiple of b. However, I'm trying to just select all the values from data frame y, that are not in x, and don't understand what function to use.
如果a = c（1,2,3），则这是有效的，因为a是b的倍数。但是，我试图只选择数据框y中的所有值，这些值不在x中，并且不了解要使用的函数。
2 个解决方案
#1
39
If I understand correctly, you need the negation of the %in% operator. Something like this should work:
如果我理解正确，您需要否定％in％运算符。像这样的东西应该工作：
subset(b, !(y %in% a$x))
子集（b，！（％y $ x中的y％））
> subset(b, !(y %in% a$x))
y
5 5
6 6
#2
19
Try the set difference function setdiff. So you would have
尝试设置差异函数setdiff。所以你会的
results1 = setdiff(a$x, b$y) # elements in a$x NOT in b$y
results2 = setdiff(b$y, a$x) # elements in b$y NOT in a$x
#1
39
If I understand correctly, you need the negation of the %in% operator. Something like this should work:
如果我理解正确，您需要否定％in％运算符。像这样的东西应该工作：
subset(b, !(y %in% a$x))
子集（b，！（％y $ x中的y％））
> subset(b, !(y %in% a$x))
y
5 5
6 6
#2
19
Try the set difference function setdiff. So you would have
尝试设置差异函数setdiff。所以你会的
results1 = setdiff(a$x, b$y) # elements in a$x NOT in b$y
results2 = setdiff(b$y, a$x) # elements in b$y NOT in a$x