Getting Historical Weather Data in R and SAP HANA

For many of my latest data blogs, I needed historical weather data to perform data mash-ups to pin-point the cause.  For example, for my continued exploration into the airlines/airports historical data using SAP HANA and R, I wanted to find out whether the weather was behind the extreme delay experienced out of a particular airport for a particular day/hour.  So I needed to mash-up the weather data with the airlines data for this analysis.

I looked around but could not find a better way to get the weather data.  So I turned to R.  Now, to get historical weather data, I am using Weather Underground's REST APIs and I put together a simple program in R to get the weather data in a data.frame.  This R module gets called from SAP HANA and it inserts a new table into HANA with the right weather information.  Once, I have the data in HANA, I performed mash-ups in HANA and off I go on my intellectual pursuit.

Weather Underground returns the data in both XML and JSON file formats.  The program logic is very simple, [once you have spent hours cracking it, the end product looks simple anyways :-)] and there are appropriate comments in the code below for self-learning.

I want to mention that you are not limited to just getting the historical view on weather data.  You can get the weather forecast for next 10 days, perform your analysis and predict future!

Make sure to register with Weather Underground (API documentation link), comply with their rules and get your own key to access their APIs.
############################################################################
getHistoricalWeather <- function(airport.code="SFO", date="Sys.Date()")
{
  base.url <- 'http://api.wunderground.com/api/{your key here}/'
  # compose final url
  final.url <- paste(base.url, 'history_', date, '/q/', airport.code, '.json', sep='')


  # reading in as raw lines from the web service
  conn <- url(final.url)
  raw.data <- readLines(conn, n=-1L, ok=TRUE)
 # Convert to a JSON
  weather.data <- fromJSON(paste(raw.data, collapse=""))
  close(conn)
  return(weather.data)
}



# get data for 10 days - restriction by Weather Underground for free usage
date.range <- seq.Date(from=as.Date('2006-1-01'), to=as.Date('2006-1-10'), by='1 day')


# Initialize a data frame
hdwd <- data.frame()



# loop over dates, and fetch weather data
for(i in seq_along(date.range)) {
    weather.data <- getHistoricalWeather('SFO', format(date.range[i], "%Y%m%d"))                 
      hdwd <- rbind(hdwd, ldply(weather.data$history$dailysummary, 
          function(x) c('SJC', date.range[i], x$fog, x$rain, x$snow,  x$meantempi, x$meanvism, x$maxtempi, x$mintempi)))
}
colnames(hdwd) <- c("Airport", "Date", 'Fog', 'Rain', 'Snow','AvgTemp', 'AvgVisibility','MaxTemp','MinTemp')


# save to CSV
write.csv(hdwd, file=gzfile('SFC-Jan2006.csv.gz'), row.names=FALSE)

############################################################################
Results - 

Airport	Date	Fog	Rain	Snow	AvgTemp	AvgVisibility	MaxTemp	MinTemp
SFO	13149	0	1	0	55	14	62	47
SFO	13150	0	1	0	53	11	55	50
SFO	13151	0	1	0	51	14	56	46
SFO	13152	0	0	0	56	16	62	50
SFO	13153	0	0	0	54	14	60	48
SFO	13154	0	1	0	52	14	59	45
SFO	13155	0	1	0	56	14	61	50
SFO	13156	0	0	0	51	16	57	45
SFO	13157	0	0	0	49	16	56	41
SFO	13158	0	0	0	54	10	61	46

Happy Analyzing!

Updated Sentiment Analysis and a Word Cloud for Netflix - The R Way!

The Netflix investors must be happy and cheerful as the stock is up more than 78% since the beginning of the year (YES, 78%, Source: Yahoo Finance!).  I am not going to talk about what turned the stock around after a much talked/hyped about Netflix debacle of the late 2011 that earned Reed Hastings quite a few UNWANTED title and every one demanded his resignation from the top post.  Not so fast, Mr. Bear!  Reed Hastings must be smiling!  After a stellar performance this year including carefully released stats on viewership, streaming hours as well as a solid Q4'11 earnings, Netflix is back and most importantly viewers are back!

Well, is is not coincidental that the sentiment for Netflix is also improving, 68% of the tweets now have positive sentiment.  See the table below:

Total	Positive	Negative	Average	Total	Sentiment
Tweets  Fetched	Tweets	Tweets	Score	Tweets
499	171	80	0.281	251	68%

*Make sure you understand and interpret this analysis correctly. This analysis is not based on NLP. 

I updated the sentiment analysis that I did last year, http://goo.gl/fkfPy ,  (I was then just beginning to play with Twitter and Text Mining packages in R) and used advanced packages like "TM" and  "WordCloud".  The new analysis is based on more than 6,800 words which are most commonly prescribed in various sentiment analysis blogs/books. (Check out Hu and Liu http://www.cs.uic.edu/~liub/FBS/sentiment-analysis.html)

I came across this excellent blog by Jeffrey Bean, @JeffreyBean, (http://goo.gl/RPkFX) and his tutorial. Thank you Mr. Bean!  Please follow the instructions from Bean's slides and the R code listed there as well as the R code here:

Here is the updated R code snippets -
#Populate the list of sentiment words from Hu and Liu (http://www.cs.uic.edu/~liub/FBS/sentiment-analysis.html)

huliu.pwords <- scan('opinion-lexicon/positive-words.txt', what='character', comment.char=';')

huliu.nwords <- scan('opinion-lexicon/negative-words.txt', what='character', comment.char=';')

# Add some words

huliu.nwords <- c(huliu.nwords,'wtf','wait','waiting','epicfail', 'crash', 'bug', 'bugy', 'bugs', 'slow', 'lie')

#Remove some words

huliu.nwords <- huliu.nwords[!huliu.nwords=='sap']

huliu.nwords <- huliu.nwords[!huliu.nwords=='cloud']

#which('sap' %in% huliu.nwords)

twitterTag <- "@Netflix"

# Get 1500 tweets - an individual is only allowed to get 1500 tweets

 tweets <- searchTwitter(tag, n=1500)

  tweets.text <- laply(tweets,function(t)t$getText())

  sentimentScoreDF <- getSentimentScore(tweets.text)

  sentimentScoreDF$TwitterTag <- twitterTag

# Get rid of tweets that have zero score and seperate +ve from -ve tweets

sentimentScoreDF$posTweets <- as.numeric(sentimentScoreDF$SentimentScore >=1)

sentimentScoreDF$negTweets <- as.numeric(sentimentScoreDF$SentimentScore <=-1)

#Summarize finidings

summaryDF <- ddply(sentimentScoreDF,"TwitterTag", summarise, 

                 TotalTweetsFetched=length(SentimentScore),

                 PositiveTweets=sum(posTweets), NegativeTweets=sum(negTweets), 

                 AverageScore=round(mean(SentimentScore),3))

summaryDF$TotalTweets <- summaryDF$PositiveTweets + summaryDF$NegativeTweets

#Get Sentiment Score

summaryDF$Sentiment  <- round(summaryDF$PositiveTweets/summaryDF$TotalTweets, 2)

Saving the best for the last, here is a word cloud (also called tag cloud) for Netflix built in R-

I will be putting the R code up here for building a word cloud after scrubbing it.

Happy Analyzing!

Sentiment Analysis, the R way, on Netflix's September 18th Announcement

Re-posting this blog from my other blog on Analytics (http://allthingsbusinessanalytics.blogspot.com/)

Did Netflix make a bad move or a bold move, only time will tell but for now here is a simple sentiment analysis using R and TwitteR package on tweets involving Netflix for you to consume...

So aftermath of #netflix supposedly bad strategic move, I thought that it will be little fun to do a little sentiment analysis using a sample of tweets from the past few days. I turned to my favorite "R" and discovered a new package called "TwitteR" and 4 lines of code later, I had the following outcome:

788 of the 1500 tweets, that is 52.5% of the tweets, over the last three days had words bad, suck, terrible or :( with #netflix...

You be the judge whether Netflix customers are unhappy and whether it was a bad (or bold) strategic move...

>  library("twitteR")

> searchNF <- searchTwitter("#netflix bad OR suck OR terrible OR disaster OR :(", n=1500, since=as.character(Sys.Date()-3))

> negativeTweets <- length(searchNF)

> negativeSentiment <- negativeTweets/1500