我一直在玩MNIST数字识别数据集,我有点卡住了。我阅读了一些研究论文,并实施了我所了解的全部内容。基本上我做的是我首先创建了我的训练集和用于评估分类器的交叉验证集,然后在测试和训练集上运行PCA,然后使用KNN和SVM执行分类任务。我面临的主要问题是,我应该在所有集合上运行PCA,然后将我的训练集和交叉验证集分开或分开,然后在交叉验证测试和训练集上单独运行PCA。我很抱歉询问我已经尝试过的事情,因为我已经尝试了两种情况,在第一种情况下,我的分类器表现出色,因为我猜测PCA使用测试数据集的同时创建了调整我的结果的主要组件,在我的模型中偏见的原因,在另一种情况下,表现是20%至30%左右,这是非常低的。所以我有点困惑,应该如何改进我的模型,高度赞赏任何帮助和指导,我已经粘贴了我的代码以供参考。MNIST数字识别数据集性能不佳
library(ggplot2)
library(e1071)
library(ElemStatLearn)
library(plyr)
library(class)
import.csv <- function(filename){
return(read.csv(filename, sep = ",", header = TRUE, stringsAsFactors = FALSE))
}
train.data <- import.csv("train.csv")
test.data <- train.data[30001:32000,]
train.data <- train.data[1:6000,]
#Performing PCA on the dataset to reduce the dimensionality of the data
get_PCA <- function(dataset){
dataset.features <- dataset[,!(colnames(dataset) %in% c("label"))]
features.unit.variance <- names(dataset[, sapply(dataset, function(v) var(v, na.rm=TRUE)==0)])
dataset.features <- dataset[,!(colnames(dataset) %in% features.unit.variance)]
pr.comp <- prcomp(dataset.features, retx = T, center = T, scale = T)
#finding the total variance contained in the principal components
prin_comp <- summary(pr.comp)
prin_comp.sdev <- data.frame(prin_comp$sdev)
#print(paste0("%age of variance contained = ", sum(prin_comp.sdev[1:500,])/sum(prin_comp.sdev)))
screeplot(pr.comp, type = "lines", main = "Principal Components")
num.of.comp = 50
red.dataset <- prin_comp$x
red.dataset <- red.dataset[,1:num.of.comp]
red.dataset <- data.frame(red.dataset)
return(red.dataset)
}
#Perform k-fold cross validation
do_cv_class <- function(df, k, classifier){
num_of_nn = gsub("[^[:digit:]]","",classifier)
classifier = gsub("[[:digit:]]","",classifier)
if(num_of_nn == "")
{
classifier = c("get_pred_",classifier)
}
else
{
classifier = c("get_pred_k",classifier)
num_of_nn = as.numeric(num_of_nn)
}
classifier = paste(classifier,collapse = "")
func_name <- classifier
output = vector()
size_distr = c()
n = nrow(df)
for(i in 1:n)
{
a = 1 + (((i-1) * n)%/%k)
b = ((i*n)%/%k)
size_distr = append(size_distr, b - a + 1)
}
row_num = 1:n
sampling = list()
for(i in 1:k)
{
s = sample(row_num,size_distr)
sampling[[i]] = s
row_num = setdiff(row_num,s)
}
prediction.df = data.frame()
outcome.list = list()
for(i in 1:k)
{
testSample = sampling[[i]]
train_set = df[-testSample,]
test_set = df[testSample,]
if(num_of_nn == "")
{
classifier = match.fun(classifier)
result = classifier(train_set,test_set)
confusion.matrix <- table(pred = result, true = test_set$label)
accuracy <- sum(diag(confusion.matrix)*100)/sum(confusion.matrix)
print(confusion.matrix)
outcome <- list(sample_ID = i, Accuracy = accuracy)
outcome.list <- rbind(outcome.list, outcome)
}
else
{
classifier = match.fun(classifier)
result = classifier(train_set,test_set)
print(class(result))
confusion.matrix <- table(pred = result, true = test_set$label)
accuracy <- sum(diag(confusion.matrix)*100)/sum(confusion.matrix)
print(confusion.matrix)
outcome <- list(sample_ID = i, Accuracy = accuracy)
outcome.list <- rbind(outcome.list, outcome)
}
}
return(outcome.list)
}
#Support Vector Machines with linear kernel
get_pred_svm <- function(train, test){
digit.class.train <- as.factor(train$label)
train.features <- train[,-train$label]
test.features <- test[,-test$label]
svm.model <- svm(train.features, digit.class.train, cost = 10, gamma = 0.0001, kernel = "radial")
svm.pred <- predict(svm.model, test.features)
return(svm.pred)
}
#KNN model
get_pred_knn <- function(train,test){
digit.class.train <- as.factor(train$label)
train.features <- train[,!colnames(train) %in% "label"]
test.features <- test[,!colnames(train) %in% "label"]
knn.model <- knn(train.features, test.features, digit.class.train)
return(knn.model)
}
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谢谢你的帮助和指导:)。 – user37940
如果它有帮助,考虑upvoting /接受:) –
我很感谢你帮助我,因为我得到了96.87%的准确性,这是惊人的,我很抱歉没有投票,因为它一直说我需要有15这样做的声誉。 – user37940