On Oct 15, 2009, at 1:17 PM, Douglas M. Hultstrand wrote:
Hello,
I have a couple questions about removing rows from a data frame and
creating a new data frame with the removed values. I provided an
example data frame (d) below.
Questions:
1) How can I search for "-999.000" and remove the entire row from
data frame "d"? (all -999 values will be in sd_diff)
2) Can I create a new data frame "d.new" that only contains the
removed rows?
3) How can I remove the last two rows from a data frame. (I used
append command to add two values to the end of the data)
> d
lat.add lon.add PPT.add Z.add sd_dif
1 37.67 -95.48 1.000 368 1.017
2 38.82 -92.22 13.208 383 5.737
3 37.30 -95.50 6.096 130 4.377
4 37.08 -95.57 0.508 106 -999.000
5 38.73 -93.55 6.350 370 6.233
6 38.83 -94.88 0.254 5 8.607
7 38.33 -96.18 0.508 43 8.665
8 38.85 -94.73 1.000 5 -999.000
9 38.71 -93.16 1.016 320 3.717
10 38.95 -95.67 1.000 5 8.553
> d.new
lat.add lon.add PPT.add Z.add sd_dif
1 37.08 -95.57 0.508 106 -999.000
2 38.85 -94.73 1.000 5 -999.000
You asked about "-999.000" which would be a character value, but you
displayed what appears to be a numeric column since there were no
quotes. That is the reason we ask for executable examples which yours
is not. You could have resolved this ambiguity if you have some
aversion to using dput(d) by at least offering the output of str(d).
At any rate, if it is a numeric column this should work even if the
-999's are not in sd_dif.
> d[apply(d , 1, function(x) -999 %in% x), ]
lat.add lon.add PPT.add Z.add sd_dif
4 37.08 -95.57 0.508 106 -999
8 38.85 -94.73 1.000 5 -999
Or if they are for certain in sd_dif, then:
d[d$sd_dif==-999, ]
Thanks for all the help,
Doug
--
---------------------------------
Douglas M. Hultstrand, MS
Senior Hydrometeorologist
Metstat, Inc. Windsor, Colorado
voice: 970.686.1253
email: dmhul...@metstat.com
web: http://www.metstat.com
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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