Robinlovelace

for each item in z List
 do 
end for

Robinlovelace

# Take a random selection of the data
set.seed(2014)
tdft <- tdft[sample(nrow(tdft), size = 1000), ]

# Select only the variables of interest
install.packages("dplyr") # library for data manipulation
tdft <- select(tdft, lat, lon, created, text,
  language, n_followers, n_tweets, user_location)

Robinlovelace

# Remove sensitive text
summary(factor(Encoding(tdft$text)))
Encoding(tdft$text) <- "UTF-8"
tdft$text <- iconv(tdft$text, "UTF-8", "UTF-8",sub='')
tdft$text <- gsub('@\\S+', '@', tdft$text) # remove all to '@' texts
tdft$text <- gsub('http\\S+', 'http', tdft$text) # remove all to hyperlinks
head(tdft$text)

Robinlovelace

# Function to reduce the max. number of words in a string
maxwords <- function(x, max = 10){
lwords <- length(x)
if(lwords > max) lwords <- max
paste0(x[1:lwords], collapse = " ")
}
# Apply maxwords to the data
tdft$text <- sapply(words, maxwords)

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# Download data

library(ggmap) # load the ggmap package
library(geosphere)

download.file("https://dl.dropboxusercontent.com/u/15008199/tmp/origins.csv", "origins.csv", method = "wget")

origins <- read.csv("origins.csv")
os <- SpatialPoints(coords = origins,
  proj4string = CRS("+init=epsg:4326"))

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# Download data

x <- c("ggmap", "geosphere", "sp")
lapply(x, library, character.only = TRUE)

download.file("https://dl.dropboxusercontent.com/u/15008199/tmp/origins.csv", "origins.csv", method = "wget")

origins <- read.csv("origins.csv")
os <- SpatialPoints(coords = origins,
  proj4string = CRS("+init=epsg:4326"))

Robinlovelace

# Loading MapInfo .mid files

library(rgdal) # rgdal library
drvs <- ogrDrivers() # ogr capabilities
drvs[grep("Inf", drvs$name),] # test MapInfo reading capability of gdal

f <- "folder/filename.mid" # filename 
l <- ogrListLayers(f) # layer name
sp_object <- readOGR(f, layer = l[[1]]) # load!

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# Install devtools if needed
if(!require(devtools)) install.packages("devtools")

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library(plotrix)
plot.bike <- function(x, ...){
  centre_back <- c(0, x$ws / 2)
  centre_front <- c(x$ws + x$ttl + 100, x$ws / 2)
  xlim <- c(-x$ws, centre_front[1] + x$ws / 2)
  ylim <- c(0, x$ttl + x$ws/2 + 50)
  plot.new()
  plot.window(xlim, ylim)
  draw.circle(x = centre_back[1], y = centre_back[2], radius = x$ws/2)
  draw.circle(x = centre_front[1], y = centre_back[2], radius = x$ws/2)

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# Create a class for bicycle data
wheelsize <- 559 # 26" wheel size, definited by 'bead seat diameter' (BSD)
size <- 21 * 25.4 # top tube length, inches converted to mm
top_tube_length <- 530 # top tobe length 
x <- list(ws = wheelsize, s = size, ttl = top_tube_length)
class(x) <- "bike"