Title: “Practical Machine Learning - Course Project”
Date: “January 13, 2016”
Question
6 participants were participated in a barbell lifting in 5 different ways.
Class A: Exactly according to the specification
Class B: Throwing the elbows to the front
Class C: Lifting the dumbbell only halfway
Class D: Lowering the dumbbell only halfway
Class E: Throwing the hips to the front
Class A perform barbell lifts correctly, while Classes B-E perform incorrectly.
By processing data gathered from accelerometers on the belt, forearm, arm, and dumbell of 6 participants in a machine learning algorithm, the question is can the appropriate activity quality (class A-E) can be predicted on testing data?
Input Data:
Initialize library
library(AppliedPredictiveModeling)
library(caret)
library(randomForest)
library(rattle)
library(rpart.plot)
library(kernlab)Downloading data from source and reading data. Treating empty values as NA.
if(!file.exists('pml-training.csv')){
download.file("https://d396qusza40orc.cloudfront.net/predmachlearn/pml-training.csv",
destfile='pml-training.csv') }
if(file.exists('pml-training.csv')){
training <- read.csv('pml-training.csv', na.strings = c(""," ","NA"), header = TRUE) }
str(training)## 'data.frame': 19622 obs. of 160 variables:
## $ X : int 1 2 3 4 5 6 7 8 9 10 ...
## $ user_name : Factor w/ 6 levels "adelmo","carlitos",..: 2 2 2 2 2 2 2 2 2 2 ...
## $ raw_timestamp_part_1 : int 1323084231 1323084231 1323084231 1323084232 1323084232 1323084232 1323084232 1323084232 1323084232 1323084232 ...
## $ raw_timestamp_part_2 : int 788290 808298 820366 120339 196328 304277 368296 440390 484323 484434 ...
## $ cvtd_timestamp : Factor w/ 20 levels "02/12/2011 13:32",..: 9 9 9 9 9 9 9 9 9 9 ...
## $ new_window : Factor w/ 2 levels "no","yes": 1 1 1 1 1 1 1 1 1 1 ...
## $ num_window : int 11 11 11 12 12 12 12 12 12 12 ...
## $ roll_belt : num 1.41 1.41 1.42 1.48 1.48 1.45 1.42 1.42 1.43 1.45 ...
## $ pitch_belt : num 8.07 8.07 8.07 8.05 8.07 8.06 8.09 8.13 8.16 8.17 ...
## $ yaw_belt : num -94.4 -94.4 -94.4 -94.4 -94.4 -94.4 -94.4 -94.4 -94.4 -94.4 ...
## $ total_accel_belt : int 3 3 3 3 3 3 3 3 3 3 ...
## $ kurtosis_roll_belt : Factor w/ 396 levels "-0.016850","-0.021024",..: NA NA NA NA NA NA NA NA NA NA ...
## $ kurtosis_picth_belt : Factor w/ 316 levels "-0.021887","-0.060755",..: NA NA NA NA NA NA NA NA NA NA ...
## $ kurtosis_yaw_belt : Factor w/ 1 level "#DIV/0!": NA NA NA NA NA NA NA NA NA NA ...
## $ skewness_roll_belt : Factor w/ 394 levels "-0.003095","-0.010002",..: NA NA NA NA NA NA NA NA NA NA ...
## $ skewness_roll_belt.1 : Factor w/ 337 levels "-0.005928","-0.005960",..: NA NA NA NA NA NA NA NA NA NA ...
## $ skewness_yaw_belt : Factor w/ 1 level "#DIV/0!": NA NA NA NA NA NA NA NA NA NA ...
## $ max_roll_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ max_picth_belt : int NA NA NA NA NA NA NA NA NA NA ...
## $ max_yaw_belt : Factor w/ 67 levels "-0.1","-0.2",..: NA NA NA NA NA NA NA NA NA NA ...
## $ min_roll_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ min_pitch_belt : int NA NA NA NA NA NA NA NA NA NA ...
## $ min_yaw_belt : Factor w/ 67 levels "-0.1","-0.2",..: NA NA NA NA NA NA NA NA NA NA ...
## $ amplitude_roll_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ amplitude_pitch_belt : int NA NA NA NA NA NA NA NA NA NA ...
## $ amplitude_yaw_belt : Factor w/ 3 levels "#DIV/0!","0.00",..: NA NA NA NA NA NA NA NA NA NA ...
## $ var_total_accel_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ avg_roll_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ stddev_roll_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ var_roll_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ avg_pitch_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ stddev_pitch_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ var_pitch_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ avg_yaw_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ stddev_yaw_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ var_yaw_belt : num NA NA NA NA NA NA NA NA NA NA ...
## $ gyros_belt_x : num 0 0.02 0 0.02 0.02 0.02 0.02 0.02 0.02 0.03 ...
## $ gyros_belt_y : num 0 0 0 0 0.02 0 0 0 0 0 ...
## $ gyros_belt_z : num -0.02 -0.02 -0.02 -0.03 -0.02 -0.02 -0.02 -0.02 -0.02 0 ...
## $ accel_belt_x : int -21 -22 -20 -22 -21 -21 -22 -22 -20 -21 ...
## $ accel_belt_y : int 4 4 5 3 2 4 3 4 2 4 ...
## $ accel_belt_z : int 22 22 23 21 24 21 21 21 24 22 ...
## $ magnet_belt_x : int -3 -7 -2 -6 -6 0 -4 -2 1 -3 ...
## $ magnet_belt_y : int 599 608 600 604 600 603 599 603 602 609 ...
## $ magnet_belt_z : int -313 -311 -305 -310 -302 -312 -311 -313 -312 -308 ...
## $ roll_arm : num -128 -128 -128 -128 -128 -128 -128 -128 -128 -128 ...
## $ pitch_arm : num 22.5 22.5 22.5 22.1 22.1 22 21.9 21.8 21.7 21.6 ...
## $ yaw_arm : num -161 -161 -161 -161 -161 -161 -161 -161 -161 -161 ...
## $ total_accel_arm : int 34 34 34 34 34 34 34 34 34 34 ...
## $ var_accel_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ avg_roll_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ stddev_roll_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ var_roll_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ avg_pitch_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ stddev_pitch_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ var_pitch_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ avg_yaw_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ stddev_yaw_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ var_yaw_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ gyros_arm_x : num 0 0.02 0.02 0.02 0 0.02 0 0.02 0.02 0.02 ...
## $ gyros_arm_y : num 0 -0.02 -0.02 -0.03 -0.03 -0.03 -0.03 -0.02 -0.03 -0.03 ...
## $ gyros_arm_z : num -0.02 -0.02 -0.02 0.02 0 0 0 0 -0.02 -0.02 ...
## $ accel_arm_x : int -288 -290 -289 -289 -289 -289 -289 -289 -288 -288 ...
## $ accel_arm_y : int 109 110 110 111 111 111 111 111 109 110 ...
## $ accel_arm_z : int -123 -125 -126 -123 -123 -122 -125 -124 -122 -124 ...
## $ magnet_arm_x : int -368 -369 -368 -372 -374 -369 -373 -372 -369 -376 ...
## $ magnet_arm_y : int 337 337 344 344 337 342 336 338 341 334 ...
## $ magnet_arm_z : int 516 513 513 512 506 513 509 510 518 516 ...
## $ kurtosis_roll_arm : Factor w/ 329 levels "-0.02438","-0.04190",..: NA NA NA NA NA NA NA NA NA NA ...
## $ kurtosis_picth_arm : Factor w/ 327 levels "-0.00484","-0.01311",..: NA NA NA NA NA NA NA NA NA NA ...
## $ kurtosis_yaw_arm : Factor w/ 394 levels "-0.01548","-0.01749",..: NA NA NA NA NA NA NA NA NA NA ...
## $ skewness_roll_arm : Factor w/ 330 levels "-0.00051","-0.00696",..: NA NA NA NA NA NA NA NA NA NA ...
## $ skewness_pitch_arm : Factor w/ 327 levels "-0.00184","-0.01185",..: NA NA NA NA NA NA NA NA NA NA ...
## $ skewness_yaw_arm : Factor w/ 394 levels "-0.00311","-0.00562",..: NA NA NA NA NA NA NA NA NA NA ...
## $ max_roll_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ max_picth_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ max_yaw_arm : int NA NA NA NA NA NA NA NA NA NA ...
## $ min_roll_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ min_pitch_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ min_yaw_arm : int NA NA NA NA NA NA NA NA NA NA ...
## $ amplitude_roll_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ amplitude_pitch_arm : num NA NA NA NA NA NA NA NA NA NA ...
## $ amplitude_yaw_arm : int NA NA NA NA NA NA NA NA NA NA ...
## $ roll_dumbbell : num 13.1 13.1 12.9 13.4 13.4 ...
## $ pitch_dumbbell : num -70.5 -70.6 -70.3 -70.4 -70.4 ...
## $ yaw_dumbbell : num -84.9 -84.7 -85.1 -84.9 -84.9 ...
## $ kurtosis_roll_dumbbell : Factor w/ 397 levels "-0.0035","-0.0073",..: NA NA NA NA NA NA NA NA NA NA ...
## $ kurtosis_picth_dumbbell : Factor w/ 400 levels "-0.0163","-0.0233",..: NA NA NA NA NA NA NA NA NA NA ...
## $ kurtosis_yaw_dumbbell : Factor w/ 1 level "#DIV/0!": NA NA NA NA NA NA NA NA NA NA ...
## $ skewness_roll_dumbbell : Factor w/ 400 levels "-0.0082","-0.0096",..: NA NA NA NA NA NA NA NA NA NA ...
## $ skewness_pitch_dumbbell : Factor w/ 401 levels "-0.0053","-0.0084",..: NA NA NA NA NA NA NA NA NA NA ...
## $ skewness_yaw_dumbbell : Factor w/ 1 level "#DIV/0!": NA NA NA NA NA NA NA NA NA NA ...
## $ max_roll_dumbbell : num NA NA NA NA NA NA NA NA NA NA ...
## $ max_picth_dumbbell : num NA NA NA NA NA NA NA NA NA NA ...
## $ max_yaw_dumbbell : Factor w/ 72 levels "-0.1","-0.2",..: NA NA NA NA NA NA NA NA NA NA ...
## $ min_roll_dumbbell : num NA NA NA NA NA NA NA NA NA NA ...
## $ min_pitch_dumbbell : num NA NA NA NA NA NA NA NA NA NA ...
## $ min_yaw_dumbbell : Factor w/ 72 levels "-0.1","-0.2",..: NA NA NA NA NA NA NA NA NA NA ...
## $ amplitude_roll_dumbbell : num NA NA NA NA NA NA NA NA NA NA ...
## [list output truncated]if(!file.exists('pml-testing.csv')){
download.file("https://d396qusza40orc.cloudfront.net/predmachlearn/pml-testing.csv",
destfile='pml-testing.csv') }
if(file.exists('pml-testing.csv')){
testing <- read.csv('pml-testing.csv', na.strings = c(""," ","NA"), header = TRUE) }
str(testing)## 'data.frame': 20 obs. of 160 variables:
## $ X : int 1 2 3 4 5 6 7 8 9 10 ...
## $ user_name : Factor w/ 6 levels "adelmo","carlitos",..: 6 5 5 1 4 5 5 5 2 3 ...
## $ raw_timestamp_part_1 : int 1323095002 1322673067 1322673075 1322832789 1322489635 1322673149 1322673128 1322673076 1323084240 1322837822 ...
## $ raw_timestamp_part_2 : int 868349 778725 342967 560311 814776 510661 766645 54671 916313 384285 ...
## $ cvtd_timestamp : Factor w/ 11 levels "02/12/2011 13:33",..: 5 10 10 1 6 11 11 10 3 2 ...
## $ new_window : Factor w/ 1 level "no": 1 1 1 1 1 1 1 1 1 1 ...
## $ num_window : int 74 431 439 194 235 504 485 440 323 664 ...
## $ roll_belt : num 123 1.02 0.87 125 1.35 -5.92 1.2 0.43 0.93 114 ...
## $ pitch_belt : num 27 4.87 1.82 -41.6 3.33 1.59 4.44 4.15 6.72 22.4 ...
## $ yaw_belt : num -4.75 -88.9 -88.5 162 -88.6 -87.7 -87.3 -88.5 -93.7 -13.1 ...
## $ total_accel_belt : int 20 4 5 17 3 4 4 4 4 18 ...
## $ kurtosis_roll_belt : logi NA NA NA NA NA NA ...
## $ kurtosis_picth_belt : logi NA NA NA NA NA NA ...
## $ kurtosis_yaw_belt : logi NA NA NA NA NA NA ...
## $ skewness_roll_belt : logi NA NA NA NA NA NA ...
## $ skewness_roll_belt.1 : logi NA NA NA NA NA NA ...
## $ skewness_yaw_belt : logi NA NA NA NA NA NA ...
## $ max_roll_belt : logi NA NA NA NA NA NA ...
## $ max_picth_belt : logi NA NA NA NA NA NA ...
## $ max_yaw_belt : logi NA NA NA NA NA NA ...
## $ min_roll_belt : logi NA NA NA NA NA NA ...
## $ min_pitch_belt : logi NA NA NA NA NA NA ...
## $ min_yaw_belt : logi NA NA NA NA NA NA ...
## $ amplitude_roll_belt : logi NA NA NA NA NA NA ...
## $ amplitude_pitch_belt : logi NA NA NA NA NA NA ...
## $ amplitude_yaw_belt : logi NA NA NA NA NA NA ...
## $ var_total_accel_belt : logi NA NA NA NA NA NA ...
## $ avg_roll_belt : logi NA NA NA NA NA NA ...
## $ stddev_roll_belt : logi NA NA NA NA NA NA ...
## $ var_roll_belt : logi NA NA NA NA NA NA ...
## $ avg_pitch_belt : logi NA NA NA NA NA NA ...
## $ stddev_pitch_belt : logi NA NA NA NA NA NA ...
## $ var_pitch_belt : logi NA NA NA NA NA NA ...
## $ avg_yaw_belt : logi NA NA NA NA NA NA ...
## $ stddev_yaw_belt : logi NA NA NA NA NA NA ...
## $ var_yaw_belt : logi NA NA NA NA NA NA ...
## $ gyros_belt_x : num -0.5 -0.06 0.05 0.11 0.03 0.1 -0.06 -0.18 0.1 0.14 ...
## $ gyros_belt_y : num -0.02 -0.02 0.02 0.11 0.02 0.05 0 -0.02 0 0.11 ...
## $ gyros_belt_z : num -0.46 -0.07 0.03 -0.16 0 -0.13 0 -0.03 -0.02 -0.16 ...
## $ accel_belt_x : int -38 -13 1 46 -8 -11 -14 -10 -15 -25 ...
## $ accel_belt_y : int 69 11 -1 45 4 -16 2 -2 1 63 ...
## $ accel_belt_z : int -179 39 49 -156 27 38 35 42 32 -158 ...
## $ magnet_belt_x : int -13 43 29 169 33 31 50 39 -6 10 ...
## $ magnet_belt_y : int 581 636 631 608 566 638 622 635 600 601 ...
## $ magnet_belt_z : int -382 -309 -312 -304 -418 -291 -315 -305 -302 -330 ...
## $ roll_arm : num 40.7 0 0 -109 76.1 0 0 0 -137 -82.4 ...
## $ pitch_arm : num -27.8 0 0 55 2.76 0 0 0 11.2 -63.8 ...
## $ yaw_arm : num 178 0 0 -142 102 0 0 0 -167 -75.3 ...
## $ total_accel_arm : int 10 38 44 25 29 14 15 22 34 32 ...
## $ var_accel_arm : logi NA NA NA NA NA NA ...
## $ avg_roll_arm : logi NA NA NA NA NA NA ...
## $ stddev_roll_arm : logi NA NA NA NA NA NA ...
## $ var_roll_arm : logi NA NA NA NA NA NA ...
## $ avg_pitch_arm : logi NA NA NA NA NA NA ...
## $ stddev_pitch_arm : logi NA NA NA NA NA NA ...
## $ var_pitch_arm : logi NA NA NA NA NA NA ...
## $ avg_yaw_arm : logi NA NA NA NA NA NA ...
## $ stddev_yaw_arm : logi NA NA NA NA NA NA ...
## $ var_yaw_arm : logi NA NA NA NA NA NA ...
## $ gyros_arm_x : num -1.65 -1.17 2.1 0.22 -1.96 0.02 2.36 -3.71 0.03 0.26 ...
## $ gyros_arm_y : num 0.48 0.85 -1.36 -0.51 0.79 0.05 -1.01 1.85 -0.02 -0.5 ...
## $ gyros_arm_z : num -0.18 -0.43 1.13 0.92 -0.54 -0.07 0.89 -0.69 -0.02 0.79 ...
## $ accel_arm_x : int 16 -290 -341 -238 -197 -26 99 -98 -287 -301 ...
## $ accel_arm_y : int 38 215 245 -57 200 130 79 175 111 -42 ...
## $ accel_arm_z : int 93 -90 -87 6 -30 -19 -67 -78 -122 -80 ...
## $ magnet_arm_x : int -326 -325 -264 -173 -170 396 702 535 -367 -420 ...
## $ magnet_arm_y : int 385 447 474 257 275 176 15 215 335 294 ...
## $ magnet_arm_z : int 481 434 413 633 617 516 217 385 520 493 ...
## $ kurtosis_roll_arm : logi NA NA NA NA NA NA ...
## $ kurtosis_picth_arm : logi NA NA NA NA NA NA ...
## $ kurtosis_yaw_arm : logi NA NA NA NA NA NA ...
## $ skewness_roll_arm : logi NA NA NA NA NA NA ...
## $ skewness_pitch_arm : logi NA NA NA NA NA NA ...
## $ skewness_yaw_arm : logi NA NA NA NA NA NA ...
## $ max_roll_arm : logi NA NA NA NA NA NA ...
## $ max_picth_arm : logi NA NA NA NA NA NA ...
## $ max_yaw_arm : logi NA NA NA NA NA NA ...
## $ min_roll_arm : logi NA NA NA NA NA NA ...
## $ min_pitch_arm : logi NA NA NA NA NA NA ...
## $ min_yaw_arm : logi NA NA NA NA NA NA ...
## $ amplitude_roll_arm : logi NA NA NA NA NA NA ...
## $ amplitude_pitch_arm : logi NA NA NA NA NA NA ...
## $ amplitude_yaw_arm : logi NA NA NA NA NA NA ...
## $ roll_dumbbell : num -17.7 54.5 57.1 43.1 -101.4 ...
## $ pitch_dumbbell : num 25 -53.7 -51.4 -30 -53.4 ...
## $ yaw_dumbbell : num 126.2 -75.5 -75.2 -103.3 -14.2 ...
## $ kurtosis_roll_dumbbell : logi NA NA NA NA NA NA ...
## $ kurtosis_picth_dumbbell : logi NA NA NA NA NA NA ...
## $ kurtosis_yaw_dumbbell : logi NA NA NA NA NA NA ...
## $ skewness_roll_dumbbell : logi NA NA NA NA NA NA ...
## $ skewness_pitch_dumbbell : logi NA NA NA NA NA NA ...
## $ skewness_yaw_dumbbell : logi NA NA NA NA NA NA ...
## $ max_roll_dumbbell : logi NA NA NA NA NA NA ...
## $ max_picth_dumbbell : logi NA NA NA NA NA NA ...
## $ max_yaw_dumbbell : logi NA NA NA NA NA NA ...
## $ min_roll_dumbbell : logi NA NA NA NA NA NA ...
## $ min_pitch_dumbbell : logi NA NA NA NA NA NA ...
## $ min_yaw_dumbbell : logi NA NA NA NA NA NA ...
## $ amplitude_roll_dumbbell : logi NA NA NA NA NA NA ...
## [list output truncated]Features
Finding the columns not matching between training and testing sets
ind <- which(is.na(pmatch(names(training), names(testing))))
names(training)[ind]## [1] "classe"names(testing)[ind]## [1] "problem_id"Perform machine learning algorithm to column “classe” in training set to predict testing data.
For machine learning algorithm to predict effectively, drop the columns which has lot of NA’s and also drop first 7 columns which consist of personal information regarding participants.
na_count <-sapply(training, function(y) sum(length(which(is.na(y)))))
na_count <- data.frame(na_count)
nonzeroind <- which(na_count == 0)
nonzeroind <- nonzeroind[8:length(nonzeroind)]Following columns are considered in the training set for perdiction algorithm.
training <- as.data.frame(training[,nonzeroind], drop = FALSE)
names(training)## [1] "roll_belt" "pitch_belt" "yaw_belt"
## [4] "total_accel_belt" "gyros_belt_x" "gyros_belt_y"
## [7] "gyros_belt_z" "accel_belt_x" "accel_belt_y"
## [10] "accel_belt_z" "magnet_belt_x" "magnet_belt_y"
## [13] "magnet_belt_z" "roll_arm" "pitch_arm"
## [16] "yaw_arm" "total_accel_arm" "gyros_arm_x"
## [19] "gyros_arm_y" "gyros_arm_z" "accel_arm_x"
## [22] "accel_arm_y" "accel_arm_z" "magnet_arm_x"
## [25] "magnet_arm_y" "magnet_arm_z" "roll_dumbbell"
## [28] "pitch_dumbbell" "yaw_dumbbell" "total_accel_dumbbell"
## [31] "gyros_dumbbell_x" "gyros_dumbbell_y" "gyros_dumbbell_z"
## [34] "accel_dumbbell_x" "accel_dumbbell_y" "accel_dumbbell_z"
## [37] "magnet_dumbbell_x" "magnet_dumbbell_y" "magnet_dumbbell_z"
## [40] "roll_forearm" "pitch_forearm" "yaw_forearm"
## [43] "total_accel_forearm" "gyros_forearm_x" "gyros_forearm_y"
## [46] "gyros_forearm_z" "accel_forearm_x" "accel_forearm_y"
## [49] "accel_forearm_z" "magnet_forearm_x" "magnet_forearm_y"
## [52] "magnet_forearm_z" "classe"Corresponding columns in the testing set.
testing <- as.data.frame(testing[,nonzeroind], drop = FALSE)
names(testing)## [1] "roll_belt" "pitch_belt" "yaw_belt"
## [4] "total_accel_belt" "gyros_belt_x" "gyros_belt_y"
## [7] "gyros_belt_z" "accel_belt_x" "accel_belt_y"
## [10] "accel_belt_z" "magnet_belt_x" "magnet_belt_y"
## [13] "magnet_belt_z" "roll_arm" "pitch_arm"
## [16] "yaw_arm" "total_accel_arm" "gyros_arm_x"
## [19] "gyros_arm_y" "gyros_arm_z" "accel_arm_x"
## [22] "accel_arm_y" "accel_arm_z" "magnet_arm_x"
## [25] "magnet_arm_y" "magnet_arm_z" "roll_dumbbell"
## [28] "pitch_dumbbell" "yaw_dumbbell" "total_accel_dumbbell"
## [31] "gyros_dumbbell_x" "gyros_dumbbell_y" "gyros_dumbbell_z"
## [34] "accel_dumbbell_x" "accel_dumbbell_y" "accel_dumbbell_z"
## [37] "magnet_dumbbell_x" "magnet_dumbbell_y" "magnet_dumbbell_z"
## [40] "roll_forearm" "pitch_forearm" "yaw_forearm"
## [43] "total_accel_forearm" "gyros_forearm_x" "gyros_forearm_y"
## [46] "gyros_forearm_z" "accel_forearm_x" "accel_forearm_y"
## [49] "accel_forearm_z" "magnet_forearm_x" "magnet_forearm_y"
## [52] "magnet_forearm_z" "problem_id"Check for covariates that have virtually no variability
nsv <- nearZeroVar(training, saveMetrics = TRUE)
nsv## freqRatio percentUnique zeroVar nzv
## roll_belt 1.101904 6.7781062 FALSE FALSE
## pitch_belt 1.036082 9.3772296 FALSE FALSE
## yaw_belt 1.058480 9.9734991 FALSE FALSE
## total_accel_belt 1.063160 0.1477933 FALSE FALSE
## gyros_belt_x 1.058651 0.7134849 FALSE FALSE
## gyros_belt_y 1.144000 0.3516461 FALSE FALSE
## gyros_belt_z 1.066214 0.8612782 FALSE FALSE
## accel_belt_x 1.055412 0.8357966 FALSE FALSE
## accel_belt_y 1.113725 0.7287738 FALSE FALSE
## accel_belt_z 1.078767 1.5237998 FALSE FALSE
## magnet_belt_x 1.090141 1.6664968 FALSE FALSE
## magnet_belt_y 1.099688 1.5187035 FALSE FALSE
## magnet_belt_z 1.006369 2.3290184 FALSE FALSE
## roll_arm 52.338462 13.5256345 FALSE FALSE
## pitch_arm 87.256410 15.7323412 FALSE FALSE
## yaw_arm 33.029126 14.6570176 FALSE FALSE
## total_accel_arm 1.024526 0.3363572 FALSE FALSE
## gyros_arm_x 1.015504 3.2769341 FALSE FALSE
## gyros_arm_y 1.454369 1.9162165 FALSE FALSE
## gyros_arm_z 1.110687 1.2638875 FALSE FALSE
## accel_arm_x 1.017341 3.9598410 FALSE FALSE
## accel_arm_y 1.140187 2.7367241 FALSE FALSE
## accel_arm_z 1.128000 4.0362858 FALSE FALSE
## magnet_arm_x 1.000000 6.8239731 FALSE FALSE
## magnet_arm_y 1.056818 4.4439914 FALSE FALSE
## magnet_arm_z 1.036364 6.4468454 FALSE FALSE
## roll_dumbbell 1.022388 84.2065029 FALSE FALSE
## pitch_dumbbell 2.277372 81.7449801 FALSE FALSE
## yaw_dumbbell 1.132231 83.4828254 FALSE FALSE
## total_accel_dumbbell 1.072634 0.2191418 FALSE FALSE
## gyros_dumbbell_x 1.003268 1.2282132 FALSE FALSE
## gyros_dumbbell_y 1.264957 1.4167771 FALSE FALSE
## gyros_dumbbell_z 1.060100 1.0498420 FALSE FALSE
## accel_dumbbell_x 1.018018 2.1659362 FALSE FALSE
## accel_dumbbell_y 1.053061 2.3748853 FALSE FALSE
## accel_dumbbell_z 1.133333 2.0894914 FALSE FALSE
## magnet_dumbbell_x 1.098266 5.7486495 FALSE FALSE
## magnet_dumbbell_y 1.197740 4.3012945 FALSE FALSE
## magnet_dumbbell_z 1.020833 3.4451126 FALSE FALSE
## roll_forearm 11.589286 11.0895933 FALSE FALSE
## pitch_forearm 65.983051 14.8557741 FALSE FALSE
## yaw_forearm 15.322835 10.1467740 FALSE FALSE
## total_accel_forearm 1.128928 0.3567424 FALSE FALSE
## gyros_forearm_x 1.059273 1.5187035 FALSE FALSE
## gyros_forearm_y 1.036554 3.7763735 FALSE FALSE
## gyros_forearm_z 1.122917 1.5645704 FALSE FALSE
## accel_forearm_x 1.126437 4.0464784 FALSE FALSE
## accel_forearm_y 1.059406 5.1116094 FALSE FALSE
## accel_forearm_z 1.006250 2.9558659 FALSE FALSE
## magnet_forearm_x 1.012346 7.7667924 FALSE FALSE
## magnet_forearm_y 1.246914 9.5403119 FALSE FALSE
## magnet_forearm_z 1.000000 8.5771073 FALSE FALSE
## classe 1.469581 0.0254816 FALSE FALSENon zero variance is FALSE for all columns considered in the training set. Hence there is no need to eliminate any covariates due to lack of variablity.
Machine Learning Algorithm
Training set has 19,622 observations (large in size). It will be time consuming to perform algorithm on large data set.
Step 1. For classe variable, divide the given training set into 4 almost equal parts (part1, part2, part3, part4).
Step 2. Split each part into a training (60%) (part1.train, part2.train, part3.train, part4.train) and testing set (40%) (part1.test, part2.test, part3.test, part4.test).
Step 3. Construct regression model using train on each training set (part1.train, part2.train, part3.train, part4.train) by defining method and cross validation.
Step 4. Predict respective testing set (part1.test, part2.test, part3.test, part4.test) and calculate the accuracy of prediction.
Step 5. Alter the method used for regression analysis, based on the accuracy for predicting testing sets.
Step 6. After achieving desired accuracy, predcit the given testing set (20 Quiz prediction) using all four regression models and compare the results of prediction and accuracy.
Step 1.
set.seed(2121)
partition <- createDataPartition(y = training$classe, p = 0.25, list = FALSE)
part1 <- training[partition,]
rest<- training[-partition,]
set.seed(2121)
partition <- createDataPartition(y = rest$classe, p = 0.33, list = FALSE)
part2 <- rest[partition,]
rest <- rest[-partition,]
set.seed(2121)
partition <- createDataPartition(y = rest$classe, p = 0.5, list = FALSE)
part3 <- rest[partition,]
part4 <- rest[-partition,]Step 2.
set.seed(2121)
inTrain <- createDataPartition(y = part1$classe, p = 0.6, list = FALSE)
part1.train <- part1[inTrain,]
part1.test <- part1[-inTrain,]
set.seed(2121)
inTrain <- createDataPartition(y = part2$classe, p = 0.6, list = FALSE)
part2.train <- part2[inTrain,]
part2.test <- part2[-inTrain,]
set.seed(2121)
inTrain <- createDataPartition(y = part3$classe, p = 0.6, list = FALSE)
part3.train <- part3[inTrain,]
part3.test <- part3[-inTrain,]
set.seed(2121)
inTrain <- createDataPartition(y = part4$classe, p = 0.6, list = FALSE)
part4.train <- part4[inTrain,]
part4.test <- part4[-inTrain,]Step 3.
set.seed(2121)
part1.modFit <- train(part1.train$classe ~., method = "rpart", data = part1.train,
trControl = trainControl(method = "cv", number = 3))
fancyRpartPlot(part1.modFit$finalModel)
part1.pred <- predict(part1.modFit, part1.test)
confusionMatrix(part1.pred,part1.test$classe)$overall['Accuracy']## Accuracy
## 0.3686894Accuracy is just 37% using method = “rpart” and cross validation. Accuracy is pretty low. We can try another method called randomForest, method = “rf”.
Step 4.
Prediction of given testing set (20 Quiz Prediction) using part1.train
set.seed(2121)
part1.modFit <- train(part1.train$classe ~., method = "rf", data = part1.train,
trControl = trainControl(method = "cv", number = 3))
part1.pred <- predict(part1.modFit, part1.test)
part1.accuracy <- confusionMatrix(part1.pred,part1.test$classe)$overall['Accuracy']
part1.accuracy## Accuracy
## 0.9602244pred1 <- predict(part1.modFit, newdata = testing)
pred1## [1] B A B A A E D B A A B C B A E E A B B B
## Levels: A B C D EPrediction of given testing set (20 Quiz Prediction) using part2.train
set.seed(2121)
part2.modFit <- train(part2.train$classe ~., method = "rf", data = part2.train,
trControl = trainControl(method = "cv", number = 3))
part2.pred <- predict(part2.modFit, part2.test)
part2.accuracy <- confusionMatrix(part2.pred,part2.test$classe)$overall['Accuracy']
part2.accuracy## Accuracy
## 0.9665121pred2 <- predict(part2.modFit, newdata = testing)
pred2## [1] B A B A A E D B A A B C B A E E A B B B
## Levels: A B C D EPrediction of given testing set (20 Quiz Prediction) using part3.train
set.seed(2121)
part3.modFit <- train(part3.train$classe ~., method = "rf", data = part3.train,
trControl = trainControl(method = "cv", number = 3))
part3.pred <- predict(part3.modFit, part3.test)
part3.accuracy <- confusionMatrix(part3.pred,part3.test$classe)$overall['Accuracy']
part3.accuracy## Accuracy
## 0.9563452pred3 <- predict(part3.modFit, newdata = testing)
pred3## [1] B A A A A E D B A A B C B A E E A B B B
## Levels: A B C D EPrediction of given testing set (20 Quiz Prediction) using part4.train
set.seed(2121)
part4.modFit <- train(part4.train$classe ~., method = "rf", data = part4.train,
trControl = trainControl(method = "cv", number = 3))
part4.pred <- predict(part4.modFit, part4.test)
part4.accuracy <- confusionMatrix(part4.pred,part4.test$classe)$overall['Accuracy']
part4.accuracy## Accuracy
## 0.960386pred4 <- predict(part4.modFit, newdata = testing)
pred4## [1] B A A A A E D B A A B C B A E E A B A B
## Levels: A B C D EComparing predictions from each part of the training data set.
pred <- data.frame(pred1,pred2,pred3,pred4)
names(pred) <- c("Data.part1", "Data.part2", "Data.part3", "Data.part4")
pred## Data.part1 Data.part2 Data.part3 Data.part4
## 1 B B B B
## 2 A A A A
## 3 B B A A
## 4 A A A A
## 5 A A A A
## 6 E E E E
## 7 D D D D
## 8 B B B B
## 9 A A A A
## 10 A A A A
## 11 B B B B
## 12 C C C C
## 13 B B B B
## 14 A A A A
## 15 E E E E
## 16 E E E E
## 17 A A A A
## 18 B B B B
## 19 B B B A
## 20 B B B BCalculate accuracy of prediction given by each part of training set and calculate “out of sample error”
Accuracy <- data.frame(part1.accuracy, part2.accuracy, part3.accuracy, part4.accuracy)
Accuracy <- round(Accuracy * 100)
OutofSampleError <- 100 - Accuracy
Accuracy <- paste(Accuracy,'%',sep = "")Accuracy of prediction by each part of training data set is:
Accuracy## [1] "96%" "97%" "96%" "96%"Out of Sample Error
Out of sample error for each part of training data set is:
OutofSampleError <- paste(OutofSampleError,'%',sep = "")
OutofSampleError## [1] "4%" "3%" "4%" "4%"Conclusion
Prediction for 20 test data is
pred1## [1] B A B A A E D B A A B C B A E E A B B B
## Levels: A B C D E