Michael Keller mhkeller

## New dataframe from columns R
unique(df[, c("a", "c")])

or

df <- subset(df, select = c(a,c))

or to drop

df <- subset(df, select = -c(a,c))

## Renaming R Column Names
names(df) <- c("column1","column2")

or by name

names(df)[names( df)=="Los_Angeles"]<-"LA"

## Turn a multi-valued variable into a binary variable
df <- read.csv("data.csv")
df$new_column1<- ifelse(df$c3 == "A",1,0)
df$new_column2<- ifelse(df$c4 == "B",1,0)
df$new_column3 <-ifelse(df$c5 == "C" & df$c6 = D, 1, 0)

via @BrianAbelson

## R Concatenating
df2 <- paste (df1$col1, df1$col2, sep = "_")

## Sorting dataframes in R
descending

df[with(df, order(-a)), ]

or

df[order(-df$col1),]


ascending

## save SVG in R, ggplot2
ggsave(ratings, file="ratings.svg")

## gist:2648781
Symbol	Meaning	Example
%d	day as a number (0-31)	01-31
%a	abbreviated weekday, Mon
%A	unabbreviated weekday,	Monday
%m	month (00-12),	00-12
%b	abbreviated month, Jan
%B	unabbreviated month,	January
%y	2-digit year
%Y	4-digit year

## gist:2891550
^(?!http).+

\.*

## gist:3120449
# Nice for then doing aggregate functions

for(t in unique(df$colToExplode)) {
     a[paste("",t,sep="")] <- ifelse(df$colToExplode==t,1,0)
}

## get_scores.R
# Function returns quater scores from Wikipedia Super Bown pages
get.scores<-function(numeral) {
    # Base URL for Wikipedia
    wp.url<-getURL(paste("http://en.wikipedia.org/wiki/Super_Bowl_",numeral,sep=""))
    wp.data<-htmlTreeParse(wp.url, useInternalNodes=TRUE)
    score.html<-getNodeSet(wp.data,"//table[@style='background-color:transparent;']")
    score.table<-readHTMLTable(score.html[[1]])
    score.table<-transform(score.table, SB=numeral)
    return(score.table)
}
	unique(df[, c("a", "c")])

	or

	df <- subset(df, select = c(a,c))

	or to drop

	df <- subset(df, select = -c(a,c))
	names(df) <- c("column1","column2")

	or by name

	names(df)[names( df)=="Los_Angeles"]<-"LA"
	df <- read.csv("data.csv")
	df$new_column1<- ifelse(df$c3 == "A",1,0)
	df$new_column2<- ifelse(df$c4 == "B",1,0)
	df$new_column3 <-ifelse(df$c5 == "C" & df$c6 = D, 1, 0)

	via @BrianAbelson
	descending

	df[with(df, order(-a)), ]

	or

	df[order(-df$col1),]


	ascending
	Symbol Meaning Example
	%d day as a number (0-31) 01-31
	%a abbreviated weekday, Mon
	%A unabbreviated weekday, Monday
	%m month (00-12), 00-12
	%b abbreviated month, Jan
	%B unabbreviated month, January
	%y 2-digit year
	%Y 4-digit year
	# Nice for then doing aggregate functions

	for(t in unique(df$colToExplode)) {
	a[paste("",t,sep="")] <- ifelse(df$colToExplode==t,1,0)
	}
	# Function returns quater scores from Wikipedia Super Bown pages
	get.scores<-function(numeral) {
	# Base URL for Wikipedia
	wp.url<-getURL(paste("http://en.wikipedia.org/wiki/Super_Bowl_",numeral,sep=""))
	wp.data<-htmlTreeParse(wp.url, useInternalNodes=TRUE)
	score.html<-getNodeSet(wp.data,"//table[@style='background-color:transparent;']")
	score.table<-readHTMLTable(score.html[[1]])
	score.table<-transform(score.table, SB=numeral)
	return(score.table)
	}