In this case I cannot see an advantage to using dplyr over subset, other
than if dplyr is your hammer then the problem will look like a nail, or if
this is one step in a larger context where dplyr is more useful.
Nor do I think this is a good use for mapply (or dplyr::group_by) because
the groups are handled differently... better to introduce a data-driven
columnar approach than to have three separate algorithms and bind the data
frames together again.
Here are three ways I came up with. I sometimes use a variation of method
3 when the logical tests are rather more complicated than this and I want
to characterize those tests in the final report.
####### reprex
DM <- read.table( text =
"GR x y
A 25 125
A 23 135
A 14 145
A 35 230
B 45 321
B 47 512
B 53 123
B 55 451
C 61 521
C 68 235
C 85 258
C 80 654", header = TRUE, stringsAsFactors = FALSE )
# 1 Hardcoded logic
DM1 <- subset( DM
, "A" == GR & 15 <= x & x <= 30
| "B" == GR & 40 <= x & x <= 50
| "C" == GR & 60 <= x & x <= 75
)
DM1
#> GR x y
#> 1 A 25 125
#> 2 A 23 135
#> 5 B 45 321
#> 6 B 47 512
#> 9 C 61 521
#> 10 C 68 235
# 2 relational approach
cond <- read.table( text =
"GR minx maxx
A 15 30
B 40 50
C 60 75
", header = TRUE )
DM2 <- merge( DM, cond, by = "GR" )
DM2 <- subset( DM2, minx <= x & x <= maxx, select = -c( minx, maxx ) )
DM2
#> GR x y
#> 1 A 25 125
#> 2 A 23 135
#> 5 B 45 321
#> 6 B 47 512
#> 9 C 61 521
#> 10 C 68 235
# 3 Construct selection vector
sel <- rep( FALSE, nrow( DM ) )
for ( i in seq.int( nrow( cond ) ) ) {
sel <- sel | ( cond$GR[ i ] == DM$GR
& cond$minx[ i ] <= DM$x
& DM$x <= cond$maxx[ i ]
)
}
DM3 <- DM[ sel, ]
DM3
#> GR x y
#> 1 A 25 125
#> 2 A 23 135
#> 5 B 45 321
#> 6 B 47 512
#> 9 C 61 521
#> 10 C 68 235
#######
On Fri, 8 Dec 2017, Michael Hannon wrote:
library(dplyr)
DM <- read.table( text='GR x y
A 25 125
A 23 135
.
.
.
)
DM %>% filter((GR == "A" & (x >= 15) & (x <= 30)) |
(GR == "B" & (x >= 40) & (x <= 50)) |
(GR == "C" & (x >= 60) & (x <= 75)))
On Fri, Dec 8, 2017 at 4:48 PM, Ashta <sewa...@gmail.com> wrote:
Hi David, Ista and all,
I have one related question Within one group I want to keep records
conditionally.
example within
group A I want keep rows that have " x" values ranged between 15 and 30.
group B I want keep rows that have " x" values ranged between 40 and 50.
group C I want keep rows that have " x" values ranged between 60 and 75.
DM <- read.table( text='GR x y
A 25 125
A 23 135
A 14 145
A 35 230
B 45 321
B 47 512
B 53 123
B 55 451
C 61 521
C 68 235
C 85 258
C 80 654',header = TRUE, stringsAsFactors = FALSE)
The end result will be
A 25 125
A 23 135
B 45 321
B 47 512
C 61 521
C 68 235
Thank you
On Wed, Dec 6, 2017 at 10:34 PM, David Winsemius <dwinsem...@comcast.net> wrote:
On Dec 6, 2017, at 4:27 PM, Ashta <sewa...@gmail.com> wrote:
Thank you Ista! Worked fine.
Here's another (possibly more direct in its logic?):
DM[ !ave(DM$x, DM$GR, FUN= function(x) {!length(unique(x))==1}), ]
GR x y
5 B 25 321
6 B 25 512
7 B 25 123
8 B 25 451
--
David
On Wed, Dec 6, 2017 at 5:59 PM, Ista Zahn <istaz...@gmail.com> wrote:
Hi Ashta,
There are many ways to do it. Here is one:
vars <- sapply(split(DM$x, DM$GR), var)
DM[DM$GR %in% names(vars[vars > 0]), ]
Best
Ista
On Wed, Dec 6, 2017 at 6:58 PM, Ashta <sewa...@gmail.com> wrote:
Thank you Jeff,
subset( DM, "B" != x ), this works if I know the group only.
But if I don't know that group in this case "B", how do I identify
group(s) that all elements of x have the same value?
On Wed, Dec 6, 2017 at 5:48 PM, Jeff Newmiller <jdnew...@dcn.davis.ca.us> wrote:
subset( DM, "B" != x )
This is covered in the Introduction to R document that comes with R.
--
Sent from my phone. Please excuse my brevity.
On December 6, 2017 3:21:12 PM PST, David Winsemius <dwinsem...@comcast.net>
wrote:
On Dec 6, 2017, at 3:15 PM, Ashta <sewa...@gmail.com> wrote:
Hi all,
In a data set I have group(GR) and two variables x and y. I want to
remove a group that have the same record for the x variable in each
row.
DM <- read.table( text='GR x y
A 25 125
A 23 135
A 14 145
A 12 230
B 25 321
B 25 512
B 25 123
B 25 451
C 11 521
C 14 235
C 15 258
C 10 654',header = TRUE, stringsAsFactors = FALSE)
In this example the output should contain group A and C as group B
has the same record for the variable x .
The result will be
A 25 125
A 23 135
A 14 145
A 12 230
C 11 521
C 14 235
C 15 258
C 10 654
Try:
DM[ !duplicated(DM$x) , ]
How do I do it R?
Thank you.
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide
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David Winsemius
Alameda, CA, USA
'Any technology distinguishable from magic is insufficiently advanced.'
-Gehm's Corollary to Clarke's Third Law
______________________________________________
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PLEASE do read the posting guide
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______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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David Winsemius
Alameda, CA, USA
'Any technology distinguishable from magic is insufficiently advanced.'
-Gehm's Corollary to Clarke's Third Law
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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