问题
training set
trainSample <- cbind(data[1:980,1], data[1:980,2]) cl <-
factor(c(data[1:980,3]))
test set
testSample <- data(data[981:1485,1], data[981:1485,2])
cl.test <- clknn
prediction
k <- knn(trainSample, testSample, cl, k = 5)
output
< k
[1] 2 2 1 1 1 1 2 1 2 1 1 2 2 2 2 2 1 1 2 2 2 2 2 2 2 2 2 2 2 1 2 2 1 1 2 2 1 1 2 2 2 2 1 2 2 2 2 2 2 1 2 2 2 2 2 2 2 2 2
[60] 2 2 2 2 1 2 2 2 2 1 2 2 1 2 2 2 1 1 2 1 2 2 1 1 1 2 1 2 2 2 1 2 2 2 2 2 1 2 1 2 2 2 2 2 2 2 2 1 2 2 2 2 1 2 2 2 2 2 2
[119] 2 2 2 1 2 2 2 2 2 2 2 1 2 2 2 2 2 2 2 2 2 1 2 2 2 2 1 2 1 1 1 1 2 2 2 2 2 2 2 2 1 2 1 2 2 2 2 2 2 1 2 2 1 2 1 2 2 2 2
[178] 2 2 2 2 1 1 2 2 2 2 2 2 2 2 2 1 1 1 1 2 2 2 2 2 2 2 2 2 2 1 2 2 2 2 2 2 2 1 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 1 2 2 2 2 1
[237] 2 2 2 2 2 1 2 2 1 2 2 1 2 2 2 2 2 1 2 2 2 2 2 2 2 1 2 2 2 2 2 2 1 2 2 1 2 2 2 2 1 2 1 2 2 2 2 1 1 2 1 2 2 2 2 1 2 2 2
[296] 2 2 2 1 2 1 2 1 1 1 2 1 2 2 1 1 2 2 1 2 1 2 2 1 2 2 2 1 2 2 2 2 2 1 2 2 2 1 2 2 2 1 2 2 2 2 2 2 2 1 2 1 1 2 2 2 1 1 2
[355] 1 2 1 2 1 2 1 2 2 2 2 2 2 1 1 1 2 1 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 1 2 2 1 2 2 2 2 2 1 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2
[414] 2 2 1 2 2 2 2 2 2 2 2 2 1 1 2 2 2 1 2 2 2 2 2 2 2 2 2 2 1 2 2 2 2 2 2 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
[473] 2 2 2 2 2 1 1 2 2 2 2 2 1 2 2 1 1 2 2 1 2 2 1 2 1 2 2 1 2 2 2 2 2
Levels: 1 2
I want "c" and "not-c" (like in my original data.csv), instead of 1 and 2 (im also not sure which number is supposed to represent which)
Can anyone help ?
回答1:
It is very easy to change the factor levels and also not get confused about which is which:
Example data:
> a <- factor(rep(c(1,2,1),50))
> a
[1] 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2
[75] 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1 2 1 1
[149] 2 1
Levels: 1 2
#this will help later as a verification
#this counts the instances for 1 and 2
> table(a)
a
1 2
100 50
So as you can see above the order of the levels is 1 first and 2 second. When you change the levels (below) the order remains the same:
#the assignment function levels can be used to change the levels
#the order will remain the same i.e. 'c' for '1' and 'not-c' for '2'
levels(a) <- c('c', 'not-c')
> a
[1] c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c
[25] c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c
[49] c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c
[73] c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c
[97] c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c
[121] c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c c not-c c
[145] c not-c c c not-c c
Levels: c not-c
And this is the verification:
> table(a)
a
c not-c
100 50
回答2:
Subscripted assignment also works. For example, here's a factor:
> a <- factor(sample(letters[1:5],100,replace=T))
> a
[1] a d d d d a d d a b a b e a c d a c a a b e e d a e d e e a a c a a a b a
[38] b b a a e b d b c a a a b e b c e d d b b c c a b a d c b c c d e b d e d
[75] a a a b e e c b c b c c d d e e d a e e e b c e b e
Levels: a b c d e
Now, let's give a couple of those levels new names:
> levels(a)[c(2,4)] <- c('y','z')
> a
[1] a z z z z a z z a y a y e a c z a c a a y e e z a e z e e a a c a a a y a
[38] y y a a e y z y c a a a y e y c e z z y y c c a y a z c y c c z e y z e z
[75] a a a y e e c y c y c c z z e e z a e e e y c e y e
Levels: a y c z e
回答3:
use forcats package.
a <- factor(rep(c(1,2,1),50))
fct_collapse(a,c = c("1"),`not-c` = c("2"))
回答4:
You can do something like this:
x<-factor(c(1,1,2,3,1), labels=c("group1","group2","group3"))
> x
[1] group1 group1 group2 group3 group1
Levels: group1 group2 group3
Or like this:
train <- read.csv("train.csv", header=TRUE)[1:1000, ]
labels <- train[,1]
来源：https://stackoverflow.com/questions/29711067/how-to-change-name-of-factor-levels