[R] Calculating the mean in one column with empty cells
William Dunlap
wdunlap at tibco.com
Sat Oct 6 18:16:32 CEST 2012
For nine numbers, R-helpers should recommend that people
show their data with dput(obj) instead of str(obj).
dput() shows everything in the object to full precision. str() shows
a summary of the object and rounds numbers to 2 digits -- it
is good for an overview of the data, but when the question is "why
did I get a mean of .066666 instead of .06547494 from my 9 numbers"
str() is not useful.
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf
> Of David Winsemius
> Sent: Saturday, October 06, 2012 9:08 AM
> To: fxen3k
> Cc: r-help at r-project.org
> Subject: Re: [R] Calculating the mean in one column with empty cells
>
>
> On Oct 6, 2012, at 1:11 AM, fxen3k wrote:
>
> > Hi,
> >
> > the first command was bringing the numbers into R directly:
> > *> testdata <- c(0.2006160108532920, 0.1321167173880490, 0.0563941428921262,
> > 0.0264198664609803, 0.0200581303857603, -0.2971754213679500,
> > -0.2353086361784190, 0.0667195538296534, 0.1755852636926560)
> >> mean(testdata)
> > [1] 0.0161584*
> >
> > Here I tried to calculate the mean with the same numbers as given above, but
> > taken from my dataset.
> > *
> >> str(dataSet2$ac_bhar_60d_4d_after_ann[1:9])
> > num [1:9] 0.2 0.13 0.06 0.03 0.02 -0.3 -0.24 0.07 0.18
> >> mean(dataSet2$ac_bhar_60d_4d_after_ann[1:9])
> > [1] 0.01666667
> > *
>
> This is something that has happened in data processing:
>
> > dat <- read.csv2(text="0,2006160108532920
> + 0,1321167173880490
> + 0,0563941428921262
> + 0,0264198664609803
> + 0,0200581303857603
> + -0,2971754213679500
> + -0,2353086361784190
> + 0,0667195538296534
> + 0,1755852636926560
> + ", header=FALSE)
> > mean(dat[[1]])
> [1] 0.0161584
>
> >
>
> > It seems that in the second case he calculates the mean with rounded numbers
> > (0.2 and not 0.20061601085...)
> > Could it be that R imports only the rounded numbers?
> > How can I build a CSV-file with numbers showing all decimal places? Because
> > I think my current CSV-file only has numbers with 2 decimal places.
> >
>
> That is more likely the fault of Excel than it is something R is responsible for.
>
> --
>
> David Winsemius, MD
> Alameda, CA, USA
>
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