R语言做GRNN的程序，运行出错求教

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1. pkgs <- c('MASS', 'doParallel', 'foreach', 'grnn')
   
2. lapply(pkgs, require, character.only = T)
   
3. registerDoParallel(cores = 8)
   
4. 
   
5. data(Boston)
   
6. # PRE-PROCESSING DATA
   
7. X <- Boston[-14]
   
8. st.X <- scale(X)
   
9. Y <- Boston[14]
   
10. boston <- data.frame(st.X, Y)
    
11. 
    
12. # SPLIT DATA SAMPLES
    
13. set.seed(2013)
    
14. rows <- sample(1:nrow(boston), nrow(boston) - 200)
    
15. set1 <- boston[rows, ]
    
16. set2 <- boston[-rows, ]
    
17. 
    
18. # DEFINE A FUNCTION TO SCORE GRNN
    
19. pred_grnn <- function(x, nn){
    
20.   xlst <- split(x, 1:nrow(x))
    
21.   pred <- foreach(i = xlst, .combine = rbind) %dopar% {
    
22.     data.frame(pred = guess(nn, as.matrix(i)), i, row.names = NULL)
    
23.   }
    
24. }
    
25. 
    
26. # SEARCH FOR THE OPTIMAL VALUE OF SIGMA BY THE VALIDATION SAMPLE
    
27. cv <- foreach(s = seq(0.2, 1, 0.05), .combine = rbind) %dopar% {
    
28.   grnn <- smooth(learn(set1, variable.column = ncol(set1)), sigma = s)
    
29.   pred <- pred_grnn(set2[, -ncol(set2)], grnn)
    
30.   test.sse <- sum((set2[, ncol(set2)] - pred$pred)^2)
    
31.   data.frame(s, sse = test.sse)
    
32. }
    
33. 
    
34. cat("\n### SSE FROM VALIDATIONS ###\n")
    
35. print(cv)
    
36. jpeg('grnn_cv.jpeg', width = 800, height = 400, quality = 100)
    
37. with(cv, plot(s, sse, type = 'b'))
    
38. 
    
39. cat("\n### BEST SIGMA WITH THE LOWEST SSE ###\n")
    
40. print(best.s <- cv[cv$sse == min(cv$sse), 1])
    
41. 
    
42. # SCORE THE WHOLE DATASET WITH GRNN
    
43. final_grnn <- smooth(learn(set1, variable.column = ncol(set1)), sigma = best.s)
    
44. pred_all <- pred_grnn(boston[, -ncol(set2)], final_grnn)
    
45. jpeg('grnn_fit.jpeg', width = 800, height = 400, quality = 100)
    
46. plot(pred_all$pred, boston$medv)
    
47. dev.off()

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关键词：运行出错 GRNN R语言 程序

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