finished week4 of compdata

Author: josephpconley

compdata/week4/ProgAssignment4.pdf

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+agecount <- function(age = NULL) {
+  ## Check that "age" is non-NULL; else throw error
+  if(is.null(age)){
+    stop("Cause cannot be NULL!")
+  }
+  
+  ## Read "homicides.txt" data file
+  homicides <- readLines("homicides.txt")
+
+  regex <- paste(" ", age, " year", sep = "")
+  
+  ## Extract ages of victims; ignore records where no age is given
+  ## Return integer containing count of homicides for that age
+  length(grep(regex, homicides))
+}

compdata/week4/agecount.R

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+count <- function(cause = NULL) {
+  ## Check that "cause" is non-NULL; else throw error
+  if(is.null(cause)){
+    stop("Cause cannot be NULL!")
+  }
+  
+  ## Check that specific "cause" is allowed; else throw error
+  range <- c("asphyxiation", "blunt force", "other", "shooting", "stabbing", "unknown")
+  
+  if(!is.element(cause, range)){
+    stop(paste("Invalid cause, must be one of ", paste(range, collapse = ', ')))
+  }
+  
+  ## Read "homicides.txt" data file
+  homicides <- readLines("homicides.txt")
+  
+  firstLetter <- substr(cause, 0, 1)
+  regex <- paste("Cause: [", firstLetter, toupper(firstLetter), "]", substr(cause, 2, nchar(cause)), sep = "")
+  
+  ## Extract causes of death
+  ## Return integer containing count of homicides for that cause
+  length(grep(regex, homicides))
+}

compdata/week4/count.R

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+#hmwk4
+getwd()
+setwd("compdata/week4")
+homicides <- readLines("homicides.txt")
+
+count("other")
+num <- count("unknown")
+print(num)
+
+agecount(3)
+agecount(1)
+num <- agecount(21)
+print(num)
+
+
+#submit
+source("http://spark-public.s3.amazonaws.com/compdata/scripts/submitscript4.R")
+submit()

compdata/week4/hmwk4.R

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+library(grDevices)
+x <- colorRamp(c("red", "blue"))
+x
+y <- colorRampPalette(c("red", "yellow"))
+y
+
+rgb(0,  0,	0,	0.2)
+
+s <- "she likes rum raisin after running hard"
+regex <- "^s(.*?)r"
+regexpr(regex, s)
+
+?setOldClass

compdata/week4/homicides.txt

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+#Colors and Plots
+library(grDevices)
+pal <- colorRamp(c("red", "blue"))
+pal
+pal(0)
+pal(1)
+pal(0.5)
+pal(seq(0, 1, len = 10))
+
+pal <- colorRampPalette(c("red", "yellow"))
+pal(2)
+pal(10)
+
+library(RColorBrewer)
+cols <- brewer.pal(3, "BuGn")
+cols
+pal <- colorRampPalette(cols)
+image(volcano, col = pal(20))
+
+x <- rnorm(10000)
+y <- rnorm(10000)
+smoothScatter(x, y)
+
+plot(x, y, pch = 19)
+plot(x,  y,	col	=	rgb(0,	0,	0,	0.2),	pch	=	19)	
+
+#Dates and Times
+x <- as.Date("1970-01-01")
+x
+
+?unclass
+unclass(x)
+unclass(as.Date("1970-01-02"))
+
+x <- Sys.time()
+x
+
+p <- as.POSIXlt(x)
+names(unclass(p))
+
+p$sec
+
+datestring <- c("January 10, 2012 10:40", "December 9, 2011 9:10")
+x <- strptime(datestring, "%B %d, %Y %H:%M")
+x
+
+x <- as.Date("2012-01-01")
+y <- strptime("9 Jan 2011 11:34:21", "%d %b %Y %H:%M:%S")
+x - y
+
+x <- as.POSIXlt(x)
+x - y
+
+x <- as.Date("2012-03-01")
+y <- as.Date("2012-02-28")
+x - y
+
+x <- as.POSIXct("2012-10-25 01:00:00")
+y <- as.POSIXct("2012-10-25 06:00:00", tz = "GMT")
+y - x
+
+#Regex
+#
+#^ matches start of a line
+#
+#$ matches end of a line
+#
+#We can list a set of characters we will accept at a given point in the match
+#[Bb][Uu][Ss][Hh]
+#
+#range of letters
+#[a-z] or [a-zA-Z]
+#
+#. refers to any character
+#
+#| means or
+#
+#? means optional
+#
+#* means 0 or many
+#
+#+ means 1 or many
+#
+#{} means interval, as in {1,5}
+
+#Bmore Homicides
+setwd("compdata/week4")
+
+#Regex in R
+homicides <- readLines("homicides.txt")
+homicides[1]
+str(homicides)
+
+length(grep("iconHomicideShooting", homicides))
+length(grep("iconHomicideShooting|icon_homicide_shooting", homicides))
+length(grep("Cause: shooting", homicides))
+length(grep("Cause: [Ss]hooting", homicides))
+length(grep("[Ss]hooting", homicides))
+
+grep("^New", state.name)
+grep("^New", state.name, value = TRUE)
+grepl("^New", state.name)
+
+regexpr("<dd>[F|f]ound(.*)</dd>", homicides[1:10])
+substr(homicides[1], 177, 177 + 93 - 1)
+
+r <- regexec("<dd>[F|f]ound on (.*?)</dd>", homicides)
+m <- regmatches(homicides, r)
+m
+dates <- sapply(m, function(x) x[2])
+dates <- as.Date(dates, "%B %d, %Y")
+hist(dates, "month", freq = TRUE)