Data-Science-Capstone Milestone Report

Introduction

This report is part of the data science capstone project of Coursera. This report describe the statistics of words in the three corpora(blogs, news, twitter).

1. Loading add-on package

library(stringi)
library(ggplot2)

2. Download the data

file_url <- "https://d396qusza40orc.cloudfront.net/dsscapstone/dataset/Coursera-SwiftKey.zip"
dest_file <- "Coursera-SwiftKey.zip"
download.file(file_url, dest_file)

3. Unzip and loading the data

unzip(dest_file)
con <- file("final/en_US/en_US.blogs.txt", open="rb")
en_blogs <- readLines(con, encoding="UTF-8", skipNul=TRUE)
close(con)
rm(con)

con <- file("final/en_US/en_US.news.txt", open="rb")
en_news <- readLines(con, encoding="UTF-8", skipNul=TRUE)
close(con)
rm(con)

con <- file("final/en_US/en_US.twitter.txt", open="rb")
en_twitter <- readLines(con, encoding="UTF-8", skipNul=TRUE)
close(con)
rm(con)

4. Describing the data size, lines and characters

blogs

file.info("final/en_US/en_US.blogs.txt")$size / 1024^2

## [1] 200.4242

stri_stats_general(en_blogs)

##       Lines LinesNEmpty       Chars CharsNWhite 
##      899288      899288   206824382   170389539

news

file.info("final/en_US/en_US.news.txt")$size / 1024^2

## [1] 196.2775

stri_stats_general(en_news)

##       Lines LinesNEmpty       Chars CharsNWhite 
##     1010242     1010242   203223154   169860866

twitter

file.info("final/en_US/en_US.twitter.txt")$size / 1024^2

## [1] 159.3641

stri_stats_general(en_twitter)

##       Lines LinesNEmpty       Chars CharsNWhite 
##     2360148     2360148   162096241   134082806

5. Summarize and plot the data

words_en_blogs <- stri_count_words(en_blogs)
words_en_news <- stri_count_words(en_news)
words_en_twitter <- stri_count_words(en_twitter)

all <- data.frame(dataset=c(rep("blogs",length(words_en_blogs)),
                          rep("news",length(words_en_news)),
                          rep("twitter", length(words_en_twitter))),
                  value=c(words_en_blogs, words_en_news, words_en_twitter))

g <- ggplot(all, aes(x=value, fill=dataset))
g + geom_histogram(alpha=0.5, position="identity") + 
    xlim(0, 300) + xlab("words") + ylab("counts")

## `stat_bin()` using `bins = 30`. Pick better value with `binwidth`.

## Warning: Removed 1946 rows containing non-finite values (stat_bin).

6. Summray

• These data file are around 200MB.

• The blogs data has around 900,000 lines, and around 200 million character.

• The news data has around 1,000,000 lines, and around 200 million character.

• The twitter data has around 2,000,000 lines, and around 160 million character.

• The number of characters of Twitter is the least, and the deviation is small.

• The mode number of character in blogs is smaller than news, but the blog has a long tail distribution.