predict() function throws error using factors on linear model in R - r

Question

I am using the "lung capacity" data set to try to set up a linear model:
library(tidyverse)
library(rvest)
h <- "https://docs.google.com/spreadsheets/d/0BxQfpNgXuWoIWUdZV1ZTc2ZscnM/edit?resourcekey=0-gqXT7Re2eUS2JGt_w1y4vA#gid=1055321634"
t <- rvest::read_html(h)
Nodes <- t %>% html_nodes("table")
table <- html_table(Nodes[[1]])
colnames(table) <- table[1,]
table <- table[-1,]
table <- table %>% select(LungCap, Age, Height, Smoke, Gender, Caesarean)
Lung_Capacity <- table
Lung_Capacity$LungCap <- as.numeric(Lung_Capacity$LungCap)
Lung_Capacity$Age <- as.numeric(Lung_Capacity$Age)
Lung_Capacity$Height <- as.numeric(Lung_Capacity$Height)
Lung_Capacity$Smoke <- as.numeric(Lung_Capacity$Smoke == "yes")
Lung_Capacity$Gender <- as.numeric(Lung_Capacity$Gender == "male")
Lung_Capacity$Caesarean <- as.numeric(Lung_Capacity$Caesarean == "yes")
colnames(Lung_Capacity)[4] <- "Smoker_YN"
colnames(Lung_Capacity)[5] <- "Male_YN"
colnames(Lung_Capacity)[6] <- "Caesarean_YN"
head(Lung_Capacity)
Capacity <- Lung_Capacity
I am splitting the data into a training set and a validation set:
library(caret)
set.seed(1)
y <- Capacity$LungCap
testIndex <- caret::createDataPartition(y, times = 1, p = 0.2, list = FALSE)
train <- Capacity[-testIndex,]
test <- Capacity[testIndex,]
Cross-validating to obtain my final model:
set.seed(3)
control <- trainControl(method="cv", number = 5)
LinearModel <- train(LungCap ~ ., data = train, method = "lm", trControl = control)
LM <- LinearModel$finalModel
summary(LM)
And trying to run a prediction on the held-out test set:
lmPredictions <- predict(LM, newdata = test)
However, there is an error thrown that reads:
Error in eval(predvars, data, env) : object 'Smoker_YN1' not found
Looking through this site, I thought the column names of the test and train tables may have been off, but that is not the case, they are identical. The issue seems to be that training the model has renamed the factor predictors "Smoker_YN1" as opposed to the column name "Smokey_YN" that is intended. I tried renaming the column headers in the test set and I tried re-naming the coefficient headers. Neither approach was successful.
I've run out of research and experimental approaches, can anyone please help with this issue?

Answer 1

I am not sure. Please go through and tell me: My guess (and I am not an expert, is that LungCap character and Lung numeric interfer in this code):
h <- "https://docs.google.com/spreadsheets/d/0BxQfpNgXuWoIWUdZV1ZTc2ZscnM/edit?resourcekey=0-gqXT7Re2eUS2JGt_w1y4vA#gid=1055321634"
#install.packages("textreadr")
library(textreadr)
library(rvest)
t <- read_html(h)
t
Nodes <- t %>% html_nodes("table")
table <- html_table(Nodes[[1]])
colnames(table) <- table[1,]
table <- table[-1,]
table <- table %>% select(LungCap, Age, Height, Smoke, Gender, Caesarean)
Lung_Capacity <- table
# I changed Lung_Capacity$LungCap <- as.numeric(Lung_Capacity$LungCap) to
Lung_Capacity$Lung <- as.numeric(Lung_Capacity$LungCap)
Lung_Capacity$Age <- as.numeric(Lung_Capacity$Age)
Lung_Capacity$Height <- as.numeric(Lung_Capacity$Height)
Lung_Capacity$Smoke <- as.numeric(Lung_Capacity$Smoke == "yes")
Lung_Capacity$Gender <- as.numeric(Lung_Capacity$Gender == "male")
Lung_Capacity$Caesarean <- as.numeric(Lung_Capacity$Caesarean == "yes")
colnames(Lung_Capacity)[4] <- "Smoker_YN"
colnames(Lung_Capacity)[5] <- "Male_YN"
colnames(Lung_Capacity)[6] <- "Caesarean_YN"
head(Lung_Capacity)
# I changed to
Capacity <- Lung_Capacity
Capacity
library(caret)
set.seed(1)
# I changed y <- Capacity$LungCap to
y <- Capacity$Lung
testIndex <- caret::createDataPartition(y, times = 1, p = 0.2, list = FALSE)
train <- Capacity[-testIndex,]
test <- Capacity[testIndex,]
# I removed
train$LungCap <- NULL
test$LungCap <- NULL
set.seed(3)
control <- trainControl(method="cv", number = 5)
# I changed LungCap to Lung
LinearModel <- train(Lung ~ ., data = train, method = "lm", trControl = control)
LM <- LinearModel$finalModel
summary(LM)
lmPredictions <- predict(LM, newdata = test)
lmPredictions
Output:
1 2 3 4 5 6 7
6.344355 10.231586 4.902900 7.500179 5.295711 9.434454 8.879997
8 9 10 11 12 13 14
12.227635 11.097691 7.775063 8.085810 6.399364 7.852107 9.480219
15 16 17 18 19 20
8.982051 10.115840 7.917863 12.089960 7.838881 9.653292