ZeccaLehn

Finding unique libraries from complete Johns Hopkins Data Science Specialization

library(knitr)

See: Data Science Certificate repo https://github.com/DataScienceSpecialization/courses

Set to your own working directory where .Rmd forked GitHub files reside

ZeccaLehn

# #Majority Vote Accuracy
# For Johns Hopkins / Machine Learning in R

# n <- 5 # Independent Classifiers
# k <- 3 # 
# 
# accuracy <- 0.7
# 
# majorityAccu(5, 3, .7) # 83.7% Accuracy
# majorityAccu(101, 51, .7) #99.9% Accuracy

ZeccaLehn

Code I presented in Johns Hopkins Data Science Capstone:

Size of compressed file as percentage of the original file

                   Adaptive 
                   Huffman Lempel-Ziv
     LaTeX file     66%      44%
     Speech file     65%     64%
     Image file      94%     88%

http://www.data-compression.com/lossless.html

ZeccaLehn

#Search installed packages by first letter -- regardless of upper/lower case (by 's' here)
grep("^[s]", attributes(installed.packages())$dimnames[[1]], value = TRUE, ignore.case = TRUE)

ZeccaLehn

# Quick GIST I wrote in the Data Science Capstone JHU forum (Dec 2014)

# It appears if the one of us draws 5 random tweets or news excerpts as the grading criteria calls for, 
# the probability that none of the five match the top-word is 32.8%--assuming the 
# true accuracy of model is 20%.

# Overall, if the top-word as criteria for success is used, where 4 reviewers using 5 random samples, 
# the probability that none of the 20 predictions match the top word is only 1.2%.

ZeccaLehn

stringToChar<- function( example ){
  
  example <- as.character(example)
  
  letters <- strsplit(example,"")[[1]] 
  
  for (i in letters[1:length(letters)] ) { print(i) }
  
}
  

ZeccaLehn

Sets the working directory in R on a Linux system after and are replaced with actual folder names.

Alows for sharing code without each user having to change the HOME variable (e.g., "home/myMachine/Projects/First"

setwd(paste0(Sys.getenv("HOME"),"/<TopDir>/<Root>")) 

For Windows, use proper slash direction and notation.

ZeccaLehn

Calls a sound -- useful when waiting...

install.packages("beepr")
library(beepr)
beep(sound = 3, expr = NULL) #Fanfare!!

1: "ping"

ZeccaLehn

# Loads current gist with function
# https://gist.github.com/timelyportfolio/1405187
# dev.off(); plot(1)

library(devtools)
source_gist("1405187")

require(quantmod)
require(PerformanceAnalytics)

ZeccaLehn

sink("file.txt", append = T, 
split = FALSE) # Direct text to "file.txt"

print("hello world") 
print("hello world again")

shell.exec("file.txt") # Open text file in editor 
unlink("file.txt") # Closes sink and now prints all to console

closeAllConnections()