Interquartile Range
Again, IQR returns two both a .25 and a .75 value and it failed, which is why I didn't use it before. Also, the first function just returns tha same value repeating. Since they are the same, before the second call, using the mode function is just a way to grab one value. I could have used average, min, max, they all would have returned the same thing. Mike
On Tue, Apr 19, 2016 at 7:24 PM, Marc Schwartz <marc_schwartz at me.com> wrote:
Hi,
Jumping into this thread mainly on the point of the mode of the
distribution, while also supporting Bert's comments below on theory.
If the vector 'x' that is being passed to this function is an integer
vector, then a tabulation of the integers can yield a 'mode', presuming of
course that there is only one unique mode. You may have to decide how you
want to handle a multi-modal discrete distribution.
If the vector 'x' is continuous (e.g. contains floating point values),
then a tabulation is going to be problematic for a variety of reasons.
In that case, prior discussions on this point, have yielded the following
estimation of the mode of a continuous distribution by using:
Mode <- function(x) {
D <- density(x)
D$x[which.max(D$y)]
}
where the second line of the function gets you the value of 'x' at the
maximum of the density estimate. Of course, there is still the possibility
of a multi-modal distribution and the nuances of which kernel is used,
etc., etc.
Food for thought.
Regards,
Marc Schwartz
On Apr 19, 2016, at 7:07 PM, Bert Gunter <bgunter.4567 at gmail.com> wrote:
Well, instead of your functions try:
Mode <- function(x) {
tabx <- table(x)
tabx[which.max(tabx)]
}
and use R's IQR function instead of yours.
... so I still don't get why you want to return a character string
instead of a value for the IQR;
and the mode of a sample defined as above is generally a bad estimator
of the mode of the distribution. To say more than that would take me
too far afield. Post on stats.stackexchange.com if you want to know
why (if it's even relevant).
Cheers,
Bert
Bert Gunter
"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Tue, Apr 19, 2016 at 4:25 PM, Michael Artz <michaeleartz at gmail.com>
wrote:
Hi,
Here is what I am doing
notGroupedAll <- ddply(data
,~groupColumn
,summarise
,col1_mean=mean(col1)
,col2_mode=Mode(col2) #Function I wrote for getting the
mode shown below
,col3_Range=myIqr(col3)
)
groupedAll <- ddply(data
,~groupColumn
,summarise
,col1_mean=mean(col1)
,col2_mode=Mode(col2) #Function I wrote for getting the
mode shown below
,col3_Range=Mode(col3)
)
#custom Mode function
Mode <- function(x) {
ux <- unique(x)
ux[which.max(tabulate(match(x, ux)))]
#the range function
myIqr <- function(x) {
paste(round(quantile(x,0.375),0),round(quantile(x,0.625),0),sep="-")
}
}
Here is what I am doing!! :)
On Tue, Apr 19, 2016 at 2:57 PM, William Dunlap <wdunlap at tibco.com>
wrote:
If you show us, not just tell us about, a self-contained example someone might show you a non-hacky way of getting the job done. (I don't see an argument to plyr::ddply called 'transform'.) Bill Dunlap TIBCO Software wdunlap tibco.com On Tue, Apr 19, 2016 at 12:18 PM, Michael Artz <michaeleartz at gmail.com
wrote:
Oh thanks for that clarification Bert! Hope you enjoyed your
coffee! I
ended up just using the transform argument in the ddply function. It
worked
and it repeated, then I called a mode function in another call to
ddply that
summarised. Kinda hacky but oh well! On Tue, Apr 19, 2016 at 12:31 PM, Bert Gunter <bgunter.4567 at gmail.com
wrote:
... and I'm getting another cup of coffee... -- Bert Bert Gunter "The trouble with having an open mind is that people keep coming
along
and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Tue, Apr 19, 2016 at 10:30 AM, Bert Gunter <
bgunter.4567 at gmail.com>
wrote:
NO NO -- I am wrong! The paste() expression is of course evaluated. It's just that a character string is returned of the form
"something -
something". I apologize for the confusion. -- Bert Bert Gunter "The trouble with having an open mind is that people keep coming
along
and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Tue, Apr 19, 2016 at 10:25 AM, Bert Gunter <
bgunter.4567 at gmail.com>
wrote:
To be precise: paste(round(quantile(x,0.25),0),round(quantile(x,0.75),0),sep="-") is an expression that evaluates to a character string: "round(quantile(x,.25),0) - round(quantile(x,0.75),0)" no matter what the argument of your function, x. Hence return(paste(...)) will return this exact character string and
never
evaluates x. Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Tue, Apr 19, 2016 at 8:34 AM, William Dunlap via R-help <r-help at r-project.org> wrote:
That didn't work Jim!
It always helps to say how the suggestion did not work. Jim's
function had a typo in it - was that the problem? Or did you not
change the call to ddply to use that function. Here is something
that might "work" for you:
library(plyr)
data <- data.frame(groupColumn=rep(1:5,1:5), col1=2^(0:14))
myIqr <- function(x) {
paste(round(quantile(x,0.25),0),round(quantile(x,0.75),0),sep="-")
}
ddply(data, ~groupColumn, summarise, col1_myIqr=myIqr(col1),
col1_IQR=stats::IQR(col1))
# groupColumn col1_myIqr col1_IQR
#1 1 1-1 0
#2 2 2-4 1
#3 3 12-24 12
#4 4 112-320 208
#5 5 2048-8192 6144
The important point is that
paste(round(quantile(x,0.25),0),round(quantile(x,0.75),0),sep="-")
is not a function, it is an expression. ddplyr wants functions.
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Tue, Apr 19, 2016 at 7:56 AM, Michael Artz
<michaeleartz at gmail.com>
wrote:
That didn't work Jim! Thanks anyway On Mon, Apr 18, 2016 at 9:02 PM, Jim Lemon <drjimlemon at gmail.com
wrote:
Hi Michael,
At a guess, try this:
iqr<-function(x) {
return(paste(round(quantile(x,0.25),0),round(quantile(x,0.75),0),sep="-")
} .col3_Range=iqr(datat$tenure) Jim On Tue, Apr 19, 2016 at 11:15 AM, Michael Artz <michaeleartz at gmail.com> wrote:
Hi, I am trying to show an interquartile range while grouping values
using
the function ddply(). So my function call now is like
groupedAll <- ddply(data
,~groupColumn
,summarise
,col1_mean=mean(col1)
,col2_mode=Mode(col2) #Function I wrote for
getting
the
mode shown below
,col3_Range=paste(as.character(round(quantile(datat$tenure,c(.25)))),
as.character(round(quantile(data$tenure,c(.75)))), sep = "-")
)
#custom Mode function
Mode <- function(x) {
ux <- unique(x)
ux[which.max(tabulate(match(x, ux)))]
}
I am not sre what is going wrong on my interquartile range
function, it
works on its own outside of ddply()
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http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.