问题
I've been searching for a number of packages in R to help me in converting dollar values to nice numerical values. I don't seem to be able to find one (in plyr package for example). The basic thing I'm looking for is simply removing the $ sign as well as translating "M" and "K" for Millions and thousands respectively.
To replicate, I can use this code below:
require(XML)
theurl <- "http://www.kickstarter.com/help/stats"
html <- htmlParse(theurl)
allProjects <- readHTMLTable(html)[[1]]
names(allProjects) <- c("Category","LaunchedProjects","TotalDollars","SuccessfulDollars","UnsuccessfulDollars","LiveDollars","LiveProjects","SuccessRate")
The data looks like this:
> tail(allProjects)
Category LaunchedProjects TotalDollars SuccessfulDollars UnsuccessfulDollars LiveDollars
8 Food 3,069 $16.79 M $13.18 M $2.78 M $822.64 K
9 Theater 4,155 $13.45 M $12.01 M $1.22 M $217.86 K
10 Comics 2,242 $12.88 M $11.07 M $941.31 K $862.18 K
11 Fashion 2,799 $9.62 M $7.59 M $1.44 M $585.98 K
12 Photography 2,794 $6.76 M $5.48 M $1.06 M $220.75 K
13 Dance 1,185 $3.43 M $3.13 M $225.82 K $71,322
LiveProjects SuccessRate
8 189 39.27%
9 111 64.09%
10 134 46.11%
11 204 27.24%
12 83 36.81%
13 40 70.22%
I ended up writing my own function:
dollarToNumber <- function(vectorInput) {
result <- c()
for (dollarValue in vectorInput) {
if (is.factor(dollarValue)) {
dollarValue = levels(dollarValue)
}
dollarValue <- gsub("(\\$|,)","",dollarValue)
if(grepl(" K",dollarValue)) {
dollarValue <- as.numeric(gsub(" K","",dollarValue)) * 1000
} else if (grepl(" M",dollarValue)) {
dollarValue <- as.numeric(gsub(" M","",dollarValue)) * 1000000
}
if (!is.numeric(dollarValue)) {
dollarValue <- as.numeric(dollarValue)
}
result <- append(result,dollarValue)
}
result
}
Then I used it to get what I wanted:
allProjects <- transform(allProjects,
LaunchedProjects = as.numeric(gsub(",","",levels(LaunchedProjects))),
TotalDollars = dollarToNumber(TotalDollars),
SuccessfulDollars = dollarToNumber(SuccessfulDollars),
UnsuccessfulDollars = dollarToNumber(UnsuccessfulDollars),
LiveDollars = dollarToNumber(LiveDollars),
LiveProjects = as.numeric(LiveProjects),
SuccessRate = as.numeric(gsub("%","",SuccessRate))/100)
Which will give me this result below:
> str(allProjects)
'data.frame': 13 obs. of 8 variables:
$ Category : Factor w/ 13 levels "Art","Comics",..: 6 8 4 9 12 11 1 7 13 2 ...
$ LaunchedProjects : num 10006 1185 1860 20025 2242 ...
$ TotalDollars : num 1.11e+08 9.68e+07 6.89e+07 6.66e+07 4.31e+07 ...
$ SuccessfulDollars : num 90990000 84960000 59020000 59390000 34910000 ...
$ UnsuccessfulDollars: num 16640000 7900000 6830000 5480000 3700000 ...
$ LiveDollars : num 3090000 3970000 3010000 1750000 4470000 ...
$ LiveProjects : num 13 7 6 11 3 10 8 4 1 2 ...
$ SuccessRate : num 0.394 0.338 0.382 0.541 0.334 ...
I'm new to R and I felt the code I've written is so ugly, surely there's a better way to do this without reinventing the wheel? I've used apply, aaply, ddply functions with no success (I was trying not to use the for loop as well...). On top of that, when dealing with the SuccessRate column, I couldn't find something like an as.percentage function in R. What am I missing?
Any guidance will be much appreciated!
回答1:
A solution that uses parse and eval:
ToNumber <- function(X)
{
A <- gsub("%","*1e-2",gsub("K","*1e+3",gsub("M","*1e+6",gsub("\\$|,","",as.character(X)),fixed=TRUE),fixed=TRUE),fixed=TRUE)
B <- try(sapply(A,function(a){eval(parse(text=a))}),silent=TRUE)
if (is.numeric(B)) return (as.numeric(B)) else return(X)
}
#----------------------------------------------------------------------
# Example:
X <-
read.table( header=TRUE,
text =
'Category LaunchedProjects TotalDollars SuccessfulDollars UnsuccessfulDollars LiveDollars LiveProjects SuccessRate
Food 3,069 "$16.79 M" "$13.18 M" "$2.78 M" "$822.64 K" 189 39.27%
Theater 4,155 "$13.45 M" "$12.01 M" "$1.22 M" "$217.86 K" 111 64.09%
Comics 2,242 "$12.88 M" "$11.07 M" "$941.31 K" "$862.18 K" 134 46.11%
Fashion 2,799 "$9.62 M" "$7.59 M" "$1.44 M" "$585.98 K" 204 27.24%
Photography 2,794 "$6.76 M" "$5.48 M" "$1.06 M" "$220.75 K" 83 36.81%
Dance 1,185 "$3.43 M" "$3.13 M" "$225.82 K" "$71,322" 40 70.22%' )
numX <- as.data.frame(lapply(as.list(X),ToNumber))
options(width=1000)
print(numX,row.names=FALSE)
# Category LaunchedProjects TotalDollars SuccessfulDollars UnsuccessfulDollars LiveDollars LiveProjects SuccessRate
# Food 3069 16790000 13180000 2780000 822640 189 0.3927
# Theater 4155 13450000 12010000 1220000 217860 111 0.6409
# Comics 2242 12880000 11070000 941310 862180 134 0.4611
# Fashion 2799 9620000 7590000 1440000 585980 204 0.2724
# Photography 2794 6760000 5480000 1060000 220750 83 0.3681
# Dance 1185 3430000 3130000 225820 71322 40 0.7022
回答2:
One thing that makes R different from other languages you might be used to is that it's better to do things in a "vectorized" way, to operate on a whole vector at a time rather than looping through each individual value. So your dollarToNumber function can be rewritten without the for loop:
dollarToNumber_vectorised <- function(vector) {
# Want the vector as character rather than factor while
# we're doing text processing operations
vector <- as.character(vector)
vector <- gsub("(\\$|,)","", vector)
# Create a numeric vector to store the results in, this will give you
# warning messages about NA values being introduced because the " K" values
# can't be converted directly to numeric
result <- as.numeric(vector)
# Find all the "$N K" values, and modify the result at those positions
k_positions <- grep(" K", vector)
result[k_positions] <- as.numeric(gsub(" K","", vector[k_positions])) * 1000
# Same for the "$ M" value
m_positions <- grep(" M", vector)
result[m_positions] <- as.numeric(gsub(" M","", vector[m_positions])) * 1000000
return(result)
}
It still gives the same output as your original function:
> dollarToNumber_vectorised(allProjects$LiveDollars)
[1] 3100000 3970000 3020000 1760000 4510000 762650 510860 823370 218590 865940
[11] 587670 221110 71934
# Don't worry too much about this warning
Warning message:
In dollarToNumber_vectorised(allProjects$LiveDollars) :
NAs introduced by coercion
> dollarToNumber(allProjects$LiveDollars)
[1] 3100000 3970000 3020000 1760000 4510000 762650 510860 823370 218590 865940
[11] 587670 221110 71934
来源：https://stackoverflow.com/questions/15014333/data-cleaning-of-dollar-values-and-percentage-in-r