[R] Help interpreting libarary(nnet) script output..URGENT
cobbler_squad
la.foma at gmail.com
Fri Jan 29 22:44:50 CET 2010
Hello,
I am pretty new to R. I am working on neural network classifiers and I am
feeding the nnet input from different regions of interest (fMRI data). The
script that I am using is this:
library (MASS)
heap_lda <-
data.frame(as.matrix(t(read.table(file="R_10_5runs_matrix9.txt")))*100000,syll
= c(rep("heap",3),rep("hoop",3),rep("hop",3)))
library(nnet)
heap_nnet <- nnet(syll ~ ., data=heap_lda, size=12,iter=100,MaxNWts=10000)
predict(heap_nnet,heap_lda,type = "class")
table(predict(heap_nnet,heap_lda,type = "class"),heap_lda$syll)
# do leave-one-out crossvalidation...
heap_nnet.out<-NULL
all = c(1:9)
for(n in all){
heap_nnet <- nnet(syll ~ ., data=heap_lda[all != n,], CV
=TRUE,size=12,iter=100,MaxNWts=10000)
heap_nnet.out <- c(heap_nnet.out,predict(heap_nnet,heap_lda[all ==
n,],type = "class"))
}
table(heap_nnet.out,heap_lda$syll)
..the output I am receiving so far is fits in this structure..(this input is
from 1 Region of interest file)
> library(MASS)
> heap_lda <-
> data.frame(as.matrix(t(read.table(file="R_10_5runs_matrix9.txt")))*100000,syll
> = c(rep("heap",3),rep("hoop",3),rep("hop",3)))
> library(nnet)
> heap_nnet <- nnet(syll ~ ., data=heap_lda, size=12,iter=100,MaxNWts=10000)
# weights: 1719
initial value 10.469219
iter 10 value 0.057269
iter 20 value 0.000276
final value 0.000069
converged
>
> predict(heap_nnet,heap_lda,type = "class")
[1] "heap" "heap" "heap" "hoop" "hoop" "hoop" "hop" "hop" "hop"
> table(predict(heap_nnet,heap_lda,type = "class"),heap_lda$syll)
heap hoop hop
heap 3 0 0
hoop 0 3 0
hop 0 0 3
> heap_nnet.out<-NULL
> all = c(1:9)
>
> for(n in all){
+ heap_nnet <- nnet(syll ~ ., data=heap_lda[all != n,], CV
=TRUE,size=12,iter=100,MaxNWts=10000)
+ heap_nnet.out <- c(heap_nnet.out,predict(heap_nnet,heap_lda[all ==
n,],type = "class"))
+ }
# weights: 1719
initial value 10.602879
iter 10 value 1.417881
iter 20 value 1.387453
iter 30 value 1.386296
final value 1.386294
converged
# weights: 1719
initial value 11.055741
iter 10 value 0.096622
iter 20 value 0.000189
final value 0.000060
converged
# weights: 1719
initial value 10.029384
iter 10 value 0.046705
final value 0.000063
converged
# weights: 1719
initial value 10.997292
iter 10 value 0.011758
final value 0.000086
converged
# weights: 1719
initial value 8.527452
iter 10 value 0.019332
final value 0.000060
converged
# weights: 1719
initial value 7.470868
iter 10 value 0.016888
final value 0.000085
converged
# weights: 1719
initial value 10.694363
iter 10 value 0.000740
iter 20 value 0.000310
final value 0.000057
converged
# weights: 1719
initial value 13.334826
iter 10 value 0.032689
final value 0.000091
converged
# weights: 1719
initial value 6.861594
iter 10 value 0.008161
final value 0.000081
converged
>
> table(heap_nnet.out,heap_lda$syll)
heap_nnet.out heap hoop hop
heap 2 1 1
hoop 0 1 0
hop 1 1 2
I am having trouble understanding how to interpret the output.
is my intuition correct and we are comparing the
heap_nnet <- nnet(syll ~ ., data=heap_lda, size=12,iter=100,MaxNWts=10000)
[[[[[# weights: 1719
initial value 10.469219
iter 10 value 0.057269
iter 20 value 0.000276
final value 0.000069
converged]]]]]
to the output of leave one out cross-validation? Is the better match the one
that goes through least iterations and arrives at the closest approximation
of the neural network classifier? General ideas/notes regarding this would
be greatly appreciated. Also, which number of weights is best, the one with
larger or the smaller number (given that our max_weights limit is set at
10000).
I apologize for my lack of familiarity with this and the resulting stupid
questions.
Thanks.
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