On Jul 27, 2009, at 2:54 PM, Mehdi Khan wrote:
i am able to return the first column, but anything else returns this:
<0 rows> (or 0-length row.names)
any idea?
I'm not sure what you're doing.
The result you're getting happens when no rows "pass" the logical test
that you are using to index the rows of your data.frame for.
Can you show the code that you are using (based on the example data
you gave) that is giving you the <0 rows> result?
-steve
On Tue, Jul 21, 2009 at 12:49 PM, Steve Lianoglou <mailinglist.honey...@gmail.com
> wrote:
On Jul 21, 2009, at 3:27 PM, Mehdi Khan wrote:
I understand your explanation about the test for even numbers.
However I am still a bit confused as to how to go about finding a
particular value. Here is an example data set
col # attr1 attr2 attr 3 LON LAT
17209 D NA NA -122.9409 38.27645
17210 BC NA NA -122.9581 38.36304
17211 B NA NA -123.6851 41.67121
17212 BC NA NA -123.0724 38.93073
17213 C NA NA -123.7240 41.84403
17214 <NA> 464 NA -122.9430 38.30988
17215 C NA NA -123.4442 40.65369
17216 BC NA NA -122.9389 38.31551
17217 C NA NA -123.0747 38.97998
17218 C NA NA -123.6580 41.59610
17219 C NA NA -123.4513 40.70992
17220 C NA NA -123.0901 39.06473
17221 BC NA NA -123.0653 38.94845
17222 BC NA NA -122.9464 38.36808
17223 <NA> 464 NA -123.0143 38.70205
17224 <NA> NA 5 -122.8609 37.94137
17225 <NA> NA 5 -122.8628 37.95057
17226 <NA> NA 7 -122.8646 37.95978
For future reference, perhaps paste this in a way that's easy for us
to paste into a running R session so we can use it, like so:
df <- data.frame(
coln=c(17209, 17210, 17211, 17212, 17213, 17214, 17215, 17216,
17217, 17218, 17219, 17220, 17221, 17222, 17223, 17224, 17225, 17226),
attr1
=
c
("D
","BC
","B","BC","C",NA,"C","BC","C","C","C","C","BC","BC",NA,NA,NA,NA),
attr2=c( NA,NA,NA,NA,NA,464,NA,NA,NA,NA,NA,NA,NA,NA,464,NA,NA,NA),
attr3=c(NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,5,5,7),
LON
=
c
( -122.9409
,-122.9581
,-123.6851
,-123.0724
,-123.7240
,-122.9430
,-123.4442
,-122.9389
,-123.0747
,-123.6580
,-123.4513
,-123.0901
,-123.0653,-122.9464,-123.0143,-122.8609,-122.8628,-122.8646),
LAT
=
c
(38.27645,38.36304,41.67121,38.93073,41.84403,38.30988,40.65369,38.31551,38.97998,41.59610,40.70992,39.06473,38.94845,38.36808,38.70205,37.94137,37.95057,37.95978
))
If I wanted to find the row with Lat = 37.95978
Using an "indexing vector":
R> lats <- df$LAT == 37.95978
# or with the %~% from before:
# lats <- df$LAT %~% 37.95978
R> df[lats,]
coln attr1 attr2 attr3 LON LAT
18 17226 <NA> NA 7 -122.8646 37.95978
Using the "subset" function:
R> subset(df, LAT == 37.95978)
coln attr1 attr2 attr3 LON LAT
18 17226 <NA> NA 7 -122.8646 37.95978
, how would i do that? How would I find the rows with BC?
R> subset(df, attr1 == 'BC')
coln attr1 attr2 attr3 LON LAT
2 17210 BC NA NA -122.9581 38.36304
4 17212 BC NA NA -123.0724 38.93073
8 17216 BC NA NA -122.9389 38.31551
13 17221 BC NA NA -123.0653 38.94845
14 17222 BC NA NA -122.9464 38.36808
If you try with an "indexing vector" the NA's will trip you up:
R> df[df$attr1 == 'BC',]
coln attr1 attr2 attr3 LON LAT
2 17210 BC NA NA -122.9581 38.36304
4 17212 BC NA NA -123.0724 38.93073
NA NA <NA> NA NA NA NA
8 17216 BC NA NA -122.9389 38.31551
13 17221 BC NA NA -123.0653 38.94845
14 17222 BC NA NA -122.9464 38.36808
NA.1 NA <NA> NA NA NA NA
NA.2 NA <NA> NA NA NA NA
NA.3 NA <NA> NA NA NA NA
NA.4 NA <NA> NA NA NA NA
So you could do something like:
> df[df$attr1 == 'BC' & !is.na(df$attr1),]
coln attr1 attr2 attr3 LON LAT
2 17210 BC NA NA -122.9581 38.36304
4 17212 BC NA NA -123.0724 38.93073
8 17216 BC NA NA -122.9389 38.31551
13 17221 BC NA NA -123.0653 38.94845
14 17222 BC NA NA -122.9464 38.36808
HTH,
-steve
--
Steve Lianoglou
Graduate Student: Physiology, Biophysics and Systems Biology
Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact
--
Steve Lianoglou
Graduate Student: Computational Systems Biology
| Memorial Sloan-Kettering Cancer Center
| Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact
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