confusionMatrix.matrix(data = df_name, reference = numeric_vector_name, positive = "increase") 错误：矩阵必须具有相等的维度

Question

I have had the error in the title of this post occur 3 times in a row now and none of the first couple of resulting similar Questions on Stack Overflow when I entered this error message into Google or Bing had answers that work for my particular situation. The script which the following lines of code come from is in my GitHub Repository for this analytics project in the R script file called "AIT 622 Big Data Analytics Project script".

### Classification Forecasting Model #5: Multivariate Adaptive Regression Splines
library(earth)
library(plotmo)
library(plotrix)
marsGrid = expand.grid(.degree = 1:2, .nprune = 2:38)
set.seed(100)
marsModelR1 = train(x = data2014, y = pr_var2014, method = "earth", 
                    preProc = c("center", "scale"), tuneGrid = marsGrid)

# compare the expected classifications in 2015 to the observed classifications in 2015
marsR1Pred = predict(marsModelR1, newdata = data2015)
> dim(marsR1Pred)
[1] 4120    1

I am adding in the following here to show what I believe might be the source of the error message/warning. > length(pr_var2014) 1 3808

marsR1_PR = postResample(pred = marsR1Pred, obs = pr_var2014)
> marsR1_PR
       RMSE    Rsquared         MAE 
         NA 1.24489e-06          NA

marsModelR1_CFM <- confusionMatrix(data = marsR1Pred, reference = pr_var2014,
                                   positive = "Increase")
> marsModelR1_CFM <- confusionMatrix(data = marsR1Pred, reference = pr_var2014,
+                                    positive = "Increase")
Error in confusionMatrix.matrix(data = marsR1Pred, reference = pr_var2014,  : 
  matrix must have equal dimensions

I have tried the following 2 attempted fixes already with the same result for both

> marsModelR1_CFM <- confusionMatrix(data = marsR1Pred, 
+                                    reference = sample(pr_var2014, length(marsR1Pred)),
+                                    positive = "Increase")
Error in confusionMatrix.matrix(data = marsR1Pred, reference = sample(pr_var2014,  : 
  matrix must have equal dimensions

> length(pr_var2014)
[1] 3808
> length(marsR1Pred)
[1] 4120
> marsModelR1_CFM <- confusionMatrix(data = marsR1Pred, 
+                                    reference = sample(pr_var2014, 4120),
+                                    positive = "Increase")
Error in confusionMatrix.matrix(data = marsR1Pred, reference = sample(pr_var2014,  : 
  matrix must have equal dimensions

Any suggestions would be much appreciated, Also, all of these commands are in the final section of my script. Part 4 at the bottom.

Answer 1

Make sure you are working with a factor for the data argument, not eg matrix .

# this will fail with similar error to yours
confusionMatrix(as.matrix(iris$Species), sample(iris$Species))
# Error in confusionMatrix.matrix(as.matrix(iris$Species), sample(iris$Species)) : 
#  matrix must have equal dimensions

# this will pass as I convert the variable to be a factor variable
confusionMatrix(as.factor(as.matrix(iris$Species)), sample(iris$Species))

for your case:

marsModelR1_CFM <- confusionMatrix(data = as.factor(marsR1Pred), 
                                   reference = sample(as.factor(pr_var2014), 4120),
                                   positive = "Increase")