R：ksvm函数-错误：对象不是矩阵

问题描述

我似乎在使用ksvm函数时遇到错误。每次尝试运行以下代码时，我都会收到错误消息

Error in model.frame.default(data = ..1,formula = x) : 
object is not a matrix

我已经问过同事，但是似乎没有人能够复制（出于任何原因）。任何援助将不胜感激。请参见下面的代码：

注意：我已经尝试使用as.matrix。我收到相同的错误

library(kernlab)

#Import airquality df
aq_df<-airquality

#Function to replace NA's
replaceNAs<-function(df,df_col)
{
  for (i in 1:dim(df)[1])
  {
    if(is.na(df_col[i]))
    {
      #print(df_col[i])
      df_col[i]<-mean(na.omit(df_col))
    }
    
  }
  return(df_col)
}

#Call the function to replace NA's with mean
aq_df$Ozone<-replaceNAs(aq_df,aq_df$Ozone)
aq_df$Solar.R<-replaceNAs(aq_df,aq_df$Solar.R)
aq_df$Wind<-replaceNAs(aq_df,aq_df$Wind)
aq_df$Temp<-replaceNAs(aq_df,aq_df$Temp)

#Setup ksvm
randindex<-sample(1:dim(aq_df)[1])
cutPoint_23<-floor(2*dim(aq_df)[1]/3)


trainData<-aq_df[randindex[1:cutPoint_23],]
testData<-aq_df[randindex[(cutPoint_23+1):dim(aq_df)[1]],]

svmOutput<-ksvm(type ~.,data=trainData,kernel="rbfdot",kpar="automatic",C=5,cross=3,prob.model=TRUE)

解决方法

变量type不在数据框中。如果您有一个名为type的变量，它将可以正常工作：

## add a variable named type
aq_df$type <- sample(1:2,nrow(aq_df),replace=TRUE)

## proceed as above
#Setup ksvm
randIndex<-sample(1:dim(aq_df)[1])
cutPoint_23<-floor(2*dim(aq_df)[1]/3)


trainData<-aq_df[randIndex[1:cutPoint_23],]
testData<-aq_df[randIndex[(cutPoint_23+1):dim(aq_df)[1]],]

svmOutput<-ksvm(type ~.,data=trainData,kernel="rbfdot",kpar="automatic",C=5,cross=3,prob.model=TRUE)

svmOutput
# Support Vector Machine object of class "ksvm" 
# 
# SV type: eps-svr  (regression) 
# parameter : epsilon = 0.1  cost C = 5 
# 
# Gaussian Radial Basis kernel function. 
# Hyperparameter : sigma =  0.161753619421595 
# 
# Number of Support Vectors : 93 
# 
# Objective Function Value : -225.2614 
# Training error : 0.413681 
# Cross validation error : 0.373122 
# Laplace distr. width : 0.952921

data-modeling r r svm