I am trying to run LOOCV kNN on this dataset (104x182 where the first 62 samples are B and the following 42 are C). I first conducted a PCA on the standardized version of this dataset (giving me 104 PCs). I then try to perform LOOCV kNN for i = 3:98 where i refers to the number of PCs I will use for my kNN model. For each i I pull out the highest accuracy, which k it occurs at and store it within a data frame.
# required packages
library(MASS)
library(class)
library(tidyverse)
library(caret)
# reading in and cleaning data
data <- read.csv("chowdary.csv")
og_data <- data[, -1]
st_data <- as.data.frame(cbind(og_data[, 1], scale(og_data[, -1])))
colnames(st_data)[1] <- "tumour"
# PCA for dimension reduction
# on standardized data
pca_all <- prcomp(og_data[, -1], center=TRUE, scale=TRUE)
# creating data frame to store best k value for each number of PCs
kdf_pca_all_cc <- tibble(i=as.numeric(), # this is for storing number of PCs used,
pca_all_k=as.numeric(), # k value,
pca_all_acc=as.numeric(), # accuracy value,
pca_all_kapp=as.numeric()) # and kappa value
# kNN
k_kNN <- 3:97 # number of PCs to use in each iteration of the model
train_control <- trainControl(method="LOOCV")
kNN_data <- as.data.frame(cbind(as.factor(st_data[, 1]), pca_all$x)) # data used in kNN model below
for (i in k_kNN){
a111 <- train(V1~ .,
method="knn",
tuneGrid=expand.grid(k=1:25),
trControl=train_control,
metric="Accuracy",
data=kNN_data[, 1:i])
b111 <- a111$results[as.integer(a111$bestTune), ] # this is to store the best accuracy rate, along with its k and kappa value
kdf_pca_all_cc <- kdf_pca_all_cc %>%
add_row(i=i-1,
pca_all_k=b111[, 1],
pca_all_acc=b111[, 2],
pca_all_kapp=b111[, 3])
}
For example, for i = 5, the kNN model would be using the following data:
head(kNN_data[, 1:5])
V1 PC1 PC2 PC3 PC4
1 1 3.299844 0.2587487 -1.00501632 2.0273727
2 1 1.427856 -1.0455044 -1.79970790 2.5244021
3 1 3.087657 1.2563404 1.67591441 -1.4270431
4 1 3.107778 1.5893396 2.65871270 -2.8217264
5 1 3.244306 0.5982652 0.37011029 0.3642425
6 1 3.000098 0.5471276 -0.01178315 1.0857886
However, whenever I try to run the for-loop, I am given the following warning message:
Error: Metric Accuracy not applicable for regression models
In addition: Warning message:
In train.default(x, y, weights = w, ...) :
You are trying to do regression and your outcome only has two possible values Are you trying to do classification? If so, use a 2 level factor as your outcome column.
I have no idea how to fix this. Any help would be much appreciated.
Also, as a side note, is there a faster way to run this for-loop? It takes quite a while but I have no idea how to make it more efficient. Thank you.
Related
Consider this synthetic dataset for classification,
library(tidyverse)
library(iml)
library(randomForest)
# Generate data
set.seed(5)
x = matrix(rnorm(2000), nrow=500)
z = x %*% matrix(c(1,1,1,1), nrow=4)
y = round(1 / (1 + exp(-z)), 0) %>% as.integer()
x = cbind(x, rnorm(500))
y_factor = as.factor(y)
data = data.frame(x, y_factor)
# Train model
rf = randomForest(y_factor ~ X1+X2+X3+X4+X5, data=data, ntree = 50)
# Compute feature importance using iml package
x_df = data[,-6]
predictor_rf <- Predictor$new(rf, data=x_df, y=y_factor)
imp_rf <- FeatureImp$new(predictor_rf, loss = "ce")
plot(imp_rf)
Here, x is a matrix with 5 independent variables, 4 of them are related to the response, and the fith is just noise. Then I train a random forest algorithm and finally compute the variable importance using feature permutation from the iml package and obtain the output from the figure below. In the manual from the package says that:
The importance is measured as
the factor by which the model’s prediction error increases when the feature is shuffled.
So here, variable X4 obtained a feature importance value of 0.2, which means that the prediction error "increased" by a factor of 0.2. However, being 0.2 a factor smaller than 1 this means that the prediction error actually decreased when doing the permutation on X2, which makes no sense to me, because on one side, it would imply that just random shuffled numbers obtain better results than the actual variables, but on the other side, the current model with the original variable obtains an accuracy of 100%. Same interpretation could be seen in the rest of the variables, except for variable X5, which was noise and obtained an importance of 0.
So... what am I missing here? What is that 0.2 value?
I'm working on a new type of code and need a little help with the ridge regularized regression. trying to build a predictive model but first i need x and y matrix rows to match.
I found something similar with a google search but their data is randomly generated and not provided like mine is. the data is a large dataset with over 500,000 observations and 670 variables.
library(rsample)
library(glmnet)
library(dplyr)
library(ggplot2)
# Create training (70%) and test (30%) sets
# Use set.seed for reproducibility
set.seed(123)
alumni_split<-initial_split(alumni, prop=.7, strata = "Id.Number")
alumni_train<-training(alumni_split)
alumni_test<-testing(alumni_split)
#----
# Create training and testing feature model matrices and response
vectors.
# we use model.matrix(...)[, -1] to discard the intercept
alumni_train_x <- model.matrix(Id.Number ~ ., alumni_train)[, -1]
alumni_test_x <- model.matrix(Id.Number ~ ., alumni_test)[, -1]
alumni_train_y <- log(alumni_train$Id.Number)
alumni_test_y <- log(alumni_test$Id.Number)
# What is the dimension of of your feature matrix?
dim(alumni_train_x)
#---- [HERE]
# Apply Ridge regression to alumni data
alumni_ridge <- glmnet(alumni_train_x, alumni_train_y, alpha = 0)
The error message (with code):
alumni_ridge <- glmnet(alumni_train_x, alumni_train_y, alpha = 0)
Error in glmnet(alumni_train_x, alumni_train_y, alpha = 0) :
number of observations in y (329870) not equal to the number of rows of
x (294648)
Relative newbie to predictive modeling--most of my training/experience is in inferential stats. I'm trying to predict student college graduation in 4 years.
Basic issue is that I've done data cleaning (imputing, centering, scaling); split that processed/transformed data into training (70%) and testing (30%) sets; balanced the data using two approaches (because data was 65%=0, 35%=1--and I've found inconsistent advice on what classifies as unbalanced, but one source suggested anything not within 40/60 range)--ROSE "BOTH" and SMOTE; and ran random forests.
For the ROSE "BOTH" models I got 0.9242 accuracy on the training set and AUC of 0.9268 for the test set.
For the SMOTE model I got 0.9943 accuracy on the training set and AUC of 0.9971 on the test set.
More details on model performance are embedded in the code copied below.
This just seems too good to be true. But, from what I've been able to find slightly improved performance on the test set would not indicate overfitting (it'd be the other way around). So, is this models performance likely really good or is it too good to be true? I have not been able to find a direct answer to this question via SO searches.
Also, in a few weeks I'll have another cohort of data I can run this on. I suppose that could be another "test" set, correct? Then I can apply this to the newest cohort for which we are interested in knowing likelihood to graduate in 4 years.
Many thanks,
Brian
#Used for predictive modeling of 4-year graduation
#IMPORT DATA
library(haven)
grad4yr <- [file path]
#DETERMINE DATA BALANCE/UNBALANCE
prop.table(table(grad4yr$graduate_4_yrs))
# 0=0.6492, 1=0.3517
#convert to factor so next step doesn't impute outcome variable
grad4yr$graduate_4_yrs <- as.factor(grad4yr$graduate_4_yrs)
#Preprocess data, RANN package used
library('RANN')
#Create proprocessed values object which includes centering, scaling, and imputing missing values using KNN
Processed_Values <- preProcess(grad4yr, method = c("knnImpute","center","scale"))
#Create new dataset with imputed values and centering/scaling
#Confirmed this results in 0 cases with missing values
grad4yr_data_processed <- predict(Processed_Values, grad4yr)
#Confirm last step results in 0 cases with missing values
sum(is.na(grad4yr_data_processed))
#[1] 0
#Convert outcome variable to numeric to ensure dummify step (next) doesn't dummify outcome variable.
grad4yr_data_processed$graduate_4_yrs <- as.factor(grad4yr_data_processed$graduate_4_yrs)
#Convert all factor variables to dummy variables; fullrank used to omit one of new dummy vars in each
#set.
dmy <- dummyVars("~ .", data = grad4yr_data_processed, fullRank = TRUE)
#Create new dataset that has the data imputed AND transformed to have dummy variables for all variables that
#will go in models.
grad4yr_processed_transformed <- data.frame(predict(dmy,newdata = grad4yr_data_processed))
#Convert outcome variable back to binary/factor for predictive models and create back variable with same name
#not entirely sure who last step created new version of outcome var with ".1" at the end
grad4yr_processed_transformed$graduate_4_yrs.1 <- as.factor(grad4yr_processed_transformed$graduate_4_yrs.1)
grad4yr_processed_transformed$graduate_4_yrs <- as.factor(grad4yr_processed_transformed$graduate_4_yrs)
grad4yr_processed_transformed$graduate_4_yrs.1 <- NULL
#Split data into training and testing/validation datasets based on outcome at 70%/30%
index <- createDataPartition(grad4yr_processed_transformed$graduate_4_yrs, p=0.70, list=FALSE)
trainSet <- grad4yr_processed_transformed[index,]
testSet <- grad4yr_processed_transformed[-index,]
#load caret
library(caret)
#Feature selection using rfe in R Caret, used with profile/comparison
control <- rfeControl(functions = rfFuncs,
method = "repeatedcv",
repeats = 10,#using k=10 per Kuhn & Johnson pp70; and per James et al pp
#https://www-bcf.usc.edu/~gareth/ISL/ISLR%20First%20Printing.pdf
verbose = FALSE)
#create traincontrol using repeated cross-validation with 10 fold 5 times
fitControl <- trainControl(method = "repeatedcv",
number = 10,
repeats = 5,
search = "random")
#Set the outcome variable object
grad4yrs <- 'graduate_4_yrs'
#set predictor variables object
predictors <- names(trainSet[!names(trainSet) %in% grad4yrs])
#create predictor profile to see what where prediction is best (by num vars)
grad4yr_pred_profile <- rfe(trainSet[,predictors],trainSet[,grad4yrs],rfeControl = control)
# Recursive feature selection
#
# Outer resampling method: Cross-Validated (10 fold, repeated 5 times)
#
# Resampling performance over subset size:
#
# Variables Accuracy Kappa AccuracySD KappaSD Selected
# 4 0.6877 0.2875 0.03605 0.08618
# 8 0.7057 0.3078 0.03461 0.08465 *
# 16 0.7006 0.2993 0.03286 0.08036
# 40 0.6949 0.2710 0.03330 0.08157
#
# The top 5 variables (out of 8):
# Transfer_Credits, HS_RANK, Admit_Term_Credits_Taken, first_enroll, Admit_ReasonUT10
#see data structure
str(trainSet)
#not copying output here, but confirms outcome var is factor and everything else is numeric
#given 65/35 split on outcome var and what can find about unbalanced data, considering unbalanced and doing steps to balance.
#using ROSE "BOTH and SMOTE to see how differently they perform. Also ran under/over with ROSE but they didn't perform nearly as
#well so removed from this script.
#SMOTE to balance data on the processed/dummified dataset
library(DMwR)#https://www3.nd.edu/~dial/publications/chawla2005data.pdf for justification
train.SMOTE <- SMOTE(graduate_4_yrs ~ ., data=grad4yr_processed_transformed, perc.over=600, perc.under=100)
#see how balanced SMOTE resulting dataset is
prop.table(table(train.SMOTE$graduate_4_yrs))
#0 1
#0.4615385 0.5384615
#open ROSE package/library
library("ROSE")
#ROSE to balance data (using BOTH) on the processed/dummified dataset
train.both <- ovun.sample(graduate_4_yrs ~ ., data=grad4yr_processed_transformed, method = "both", p=.5,
N = 2346)$data
#see how balanced BOTH resulting dataset is
prop.table(table(train.both$graduate_4_yrs))
#0 1
#0.4987212 0.5012788
#ROSE to balance data (using BOTH) on the processed/dummified dataset
table(grad4yr_processed_transformed$graduate_4_yrs)
#0 1
#1144 618
library("caret")
#create random forests using balanced data from above
RF_model_both <- train(train.both[,predictors],train.both[, grad4yrs],method = 'rf', trControl = fitControl, ntree=1000, tuneLength = 10)
#print info on accuracy & kappa for "BOTH" training model
# print(RF_model_both)
# Random Forest
#
# 2346 samples
# 40 predictor
# 2 classes: '0', '1'
#
# No pre-processing
# Resampling: Cross-Validated (10 fold, repeated 5 times)
# Summary of sample sizes: 2112, 2111, 2111, 2112, 2111, 2112, ...
# Resampling results across tuning parameters:
#
# mtry Accuracy Kappa
# 8 0.9055406 0.8110631
# 11 0.9053719 0.8107246
# 12 0.9057981 0.8115770
# 13 0.9054584 0.8108965
# 14 0.9048602 0.8097018
# 20 0.9034992 0.8069796
# 26 0.9027307 0.8054427
# 30 0.9034152 0.8068113
# 38 0.9023899 0.8047622
# 40 0.9032428 0.8064672
# Accuracy was used to select the optimal model using the largest value.
# The final value used for the model was mtry = 12.
RF_model_SMOTE <- train(train.SMOTE[,predictors],train.SMOTE[, grad4yrs],method = 'rf', trControl = fitControl, ntree=1000, tuneLength = 10)
#print info on accuracy & kappa for "SMOTE" training model
# print(RF_model_SMOTE)
# Random Forest
#
# 8034 samples
# 40 predictor
# 2 classes: '0', '1'
#
# No pre-processing
# Resampling: Cross-Validated (10 fold, repeated 5 times)
# Summary of sample sizes: 7231, 7231, 7230, 7230, 7231, 7231, ...
# Resampling results across tuning parameters:
#
# mtry Accuracy Kappa
# 17 0.9449082 0.8899939
# 19 0.9458047 0.8917740
# 21 0.9458543 0.8918695
# 29 0.9470243 0.8941794
# 31 0.9468750 0.8938864
# 35 0.9468003 0.8937290
# 36 0.9463772 0.8928876
# 40 0.9463275 0.8927828
#
# Accuracy was used to select the optimal model using the largest value.
# The final value used for the model was mtry = 29.
#Given that both accuracy and kappa appear better in the "SMOTE" random forest it's looking like it's the better model.
#But, running ROC/AUC on both to see how they both perform on validation data.
#Create predictions based on random forests above
rf_both_predictions <- predict.train(object=RF_model_both,testSet[, predictors], type ="raw")
rf_SMOTE_predictions <- predict.train(object=RF_model_SMOTE,testSet[, predictors], type ="raw")
#Create predictions based on random forests above
rf_both_pred_prob <- predict.train(object=RF_model_both,testSet[, predictors], type ="prob")
rf_SMOTE_pred_prob <- predict.train(object=RF_model_SMOTE,testSet[, predictors], type ="prob")
#create Random Forest confusion matrix to evaluate random forests
confusionMatrix(rf_both_predictions,testSet[,grad4yrs], positive = "1")
#output copied here:
# Confusion Matrix and Statistics
#
# Reference
# Prediction 0 1
# 0 315 12
# 1 28 173
#
# Accuracy : 0.9242
# 95% CI : (0.8983, 0.9453)
# No Information Rate : 0.6496
# P-Value [Acc > NIR] : < 2e-16
#
# Kappa : 0.8368
# Mcnemar's Test P-Value : 0.01771
#
# Sensitivity : 0.9351
# Specificity : 0.9184
# Pos Pred Value : 0.8607
# Neg Pred Value : 0.9633
# Prevalence : 0.3504
# Detection Rate : 0.3277
# Detection Prevalence : 0.3807
# Balanced Accuracy : 0.9268
#
# 'Positive' Class : 1
# confusionMatrix(rf_under_predictions,testSet[,grad4yrs], positive = "1")
#output copied here:
#Accuracy : 0.8258
#only copied accuracy as it was fair below two other versions
confusionMatrix(rf_SMOTE_predictions,testSet[,grad4yrs], positive = "1")
#output copied here:
# Confusion Matrix and Statistics
#
# Reference
# Prediction 0 1
# 0 340 0
# 1 3 185
#
# Accuracy : 0.9943
# 95% CI : (0.9835, 0.9988)
# No Information Rate : 0.6496
# P-Value [Acc > NIR] : <2e-16
#
# Kappa : 0.9876
# Mcnemar's Test P-Value : 0.2482
#
# Sensitivity : 1.0000
# Specificity : 0.9913
# Pos Pred Value : 0.9840
# Neg Pred Value : 1.0000
# Prevalence : 0.3504
# Detection Rate : 0.3504
# Detection Prevalence : 0.3561
# Balanced Accuracy : 0.9956
#
# 'Positive' Class : 1
#put predictions in dataset
testSet$rf_both_pred <- rf_both_predictions#predictions (BOTH)
testSet$rf_SMOTE_pred <- rf_SMOTE_predictions#probabilities (BOTH)
testSet$rf_both_prob <- rf_both_pred_prob#predictions (SMOTE)
testSet$rf_SMOTE_prob <- rf_SMOTE_pred_prob#probabilities (SMOTE)
library(pROC)
#get AUC of the BOTH predictions
testSet$rf_both_pred <- as.numeric(testSet$rf_both_pred)
Both_ROC_Curve <- roc(response = testSet$graduate_4_yrs,
predictor = testSet$rf_both_pred,
levels = rev(levels(testSet$graduate_4_yrs)))
auc(Both_ROC_Curve)
# Area under the curve: 0.9268
#get AUC of the SMOTE predictions
testSet$rf_SMOTE_pred <- as.numeric(testSet$rf_SMOTE_pred)
SMOTE_ROC_Curve <- roc(response = testSet$graduate_4_yrs,
predictor = testSet$rf_SMOTE_pred,
levels = rev(levels(testSet$graduate_4_yrs)))
auc(SMOTE_ROC_Curve)
#Area under the curve: 0.9971
#So, the SMOTE balanced data performed very well on training data and near perfect on the validation/test data.
#But, it seems almost too good to be true.
#Is there anything I might have missed or performed incorrectly?
I'll post as an answer my comment, even if this might be migrated.
I really think that you're overfitting, because you have balanced on the whole dataset.
Instead you should balance only the train set.
Here is your code:
library(DMwR)
train.SMOTE <- SMOTE(graduate_4_yrs ~ ., data=grad4yr_processed_transformed,
perc.over=600, perc.under=100)
By doing so your train.SMOTE now contains information from the test set too, so when you'll test on your testSet the model will have already seen part of the data, and this will likely be the cause of your "too good" results.
It should be:
library(DMwR)
train.SMOTE <- SMOTE(graduate_4_yrs ~ ., data=trainSet, # use only the train set
perc.over=600, perc.under=100)
I have two different data sets. Each of them represents one portfolio of my two portfolios.
y(p) as dependent variable and x1(p), x2(p),x3(p),x4(p) as independent variables.
(p) indicates a portfolio-specific value. column 1 of each variable represents portfolio 1 and column 2 represents portfolio 2.
The regression equation is:
y(p)=∝(p)+ 𝛽1(p)*x1(p)+𝛽2(p)*x2(p)+𝛽3(p)*x3(p)+𝛽4(p)*x4(p)
What i did so far is to implement a separate regression model for each portfolio in R:
lm1 <- lm(y[,1]~x1[,1]+x2[,1]+x3[,1]+x4[,1])
lm2 <- lm(y[,2]~x1[,2]+x2[,2]+x3[,2]+x4[,2])
My objective is to compare the two intercepts of both regression models. Within the scope of this comparison i need to test the joint significance of these intercepts. As far as i can tell, using the wald test should be appropriate.
If I use the waldtest-function from the lmtest-package it does not work.
Obviously, because the response variable is not the same for both models.
library(lmtest)
waldtest(lm1,lm2)
In waldtest.default(object, ..., test = match.arg(test)) :
models with response "y[, 2]" removed because response differs from model 1
All workarounds I tried so far did not work either, e.g. R: Waldtest: "Error in solve.default(vc[ovar, ovar]) : 'a' is 0-diml"
My guess is that the regression needs to be done in a different way to fix the problems regarding the waldtest.
So that leads to my question:
Is there a possibility to do the regression in one model, which still generates portfolio-specific intercepts and coefficients? (I assume, that this would fix the problems with the waldtest-function.)
Any advice or suggestion will be appreciated.
The following data can be used for a reproducible example:
y=matrix(rnorm(10),ncol=2)
x1=matrix(rnorm(10),ncol=2)
x2=matrix(rnorm(10),ncol=2)
x3=matrix(rnorm(10),ncol=2)
x4=matrix(rnorm(10),ncol=2)
lm1 <- lm(y[,1]~x1[,1]+x2[,1]+x3[,1]+x4[,1])
lm2 <- lm(y[,2]~x1[,2]+x2[,2]+x3[,2]+x4[,2])
library(lmtest)
waldtest(lm1,lm2)
Best regards,
Simon
Here are three ways to test intercepts equality. The second one is an implementation of the accepted answer to this question, while the other two are implementations of the second answer to the aforementioned question under different assumptions.
Let
n <- 5
y <- matrix(rnorm(10), ncol = 2)
x <- matrix(rnorm(10), ncol = 2)
First, we may indeed perform the test with only a single model. For that purpose we create a new vector Y that concatenates y[, 1] and y[, 2]. As for the independent variables, we create a block-diagonal matrix with the regressors of one model at the upper-left block and those for the other model at the lower-right block. Lastly, I create a group factor indicating the hidden model. Hence,
library(Matrix)
Y <- c(y)
X <- as.matrix(bdiag(x[, 1], x[, 2]))
G <- factor(rep(0:1, each = n))
Now the unrestricted model is
m1 <- lm(Y ~ G + X - 1)
while the restricted one is
m2 <- lm(Y ~ X)
Testing for intercepts equality gives
library(lmtest)
waldtest(m1, m2)
# Wald test
#
# Model 1: Y ~ G + X - 1
# Model 2: Y ~ X
# Res.Df Df F Pr(>F)
# 1 6
# 2 7 -1 0.5473 0.4873
so that, as expected, we cannot reject they equality. A problem with this solution, however, is that it is like estimating the two models separately but assuming that the errors have the same variance in both. Also, we don't allow for a cross-correlation between errors.
Second, we can relax the assumption of identical errors variance by estimating two separate models and employing a Z-test as follows.
M1 <- lm(y[, 1] ~ x[, 1])
M2 <- lm(y[, 2] ~ x[, 2])
Z <- unname((coef(M1)[1] - coef(M2)[1]) / (coef(summary(M1))[1, 2]^2 + coef(summary(M2))[1, 2])^2)
2 * pnorm(-abs(Z))
# [1] 0.5425736
leading to the same conclusion.
Lastly, we can employ the SUR in this way allowing for model-dependent errors variance as well as contemporaneous errors cross-dependence (that may be not necessary in your case, it matters what kind of data you are using). For that we can use the systemfit package as follows:
library(systemfit)
eq1 <- y[, 1] ~ x[, 1]
eq2 <- y[, 2] ~ x[, 2]
m <- systemfit(list(eq1, eq2), method = "SUR")
In this case we also are able to perform the Wald test:
R <- matrix(c(1, 0, -1, 0), nrow = 1) # Restriction matrix
linearHypothesis(m, R, test = "Chisq")
# Linear hypothesis test (Chi^2 statistic of a Wald test)
#
# Hypothesis:
# eq1_((Intercept) - eq2_(Intercept) = 0
#
# Model 1: restricted model
# Model 2: m
#
# Res.Df Df Chisq Pr(>Chisq)
# 1 7
# 2 6 1 0.3037 0.5816
I'm new to R but am slowly learning it to analyse a data set.
Let's say I have a data frame which contains 8 variables and 20 observations. Of the 8 variables, V1 - V3 are predictors and V4 - V8 are outcomes.
B = matrix(c(1:160),
nrow = 20,
ncol = 8,)
df <- as.data.frame(B)
Using the car package, to perform a simple linear regression, display summary and confidence intervals is:
fit <- lm(V4 ~ V1, data = df)
summary(fit)
confint(fit)
How can I write code (loop or apply) so that R regresses each predictor on each outcome individually and extracts the coefficients and confidence intervals? I realise I'm probably trying to run before I can walk but any help would be really appreciated.
You could wrap your lines in a lapply call and train a linear model for each of your predictors (excluding the target, of course).
my.target <- 4
my.predictors <- 1:8[-my.target]
lapply(my.predictors, (function(i){
fit <- lm(df[,my.target] ~ df[,i])
list(summary= summary(fit), confint = confint(fit))
}))
You obtain a list of lists.
So, the code in my own data that returns the error is:
my.target <- metabdata[c(34)]
my.predictors <- metabdata[c(18 : 23)]
lapply(my.predictors, (function(i){
fit <- lm(metabdata[, my.target] ~ metabdata[, i])
list(summary = summary(fit), confint = confint(fit))
}))
Returns:
Error: Unsupported index type: tbl_df