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Issue with %in% - not matching identical rows in data frames

3 messages · Kaushik Krishnan, Sundar Dorai-Raj, Charles C. Berry

#
Hi folks

I have two data frames.  I know that the nth (let's say the 7th) row
in the first data frame (sequence) is there in the second
(today.sequence).  When I try to check that by doing 'sequence[7,]
%in% today.sequence', I get all FALSE when it should be all TRUE.

I'm certain I'm making some trivial mistake.  Any solutions?

The code to recreate the data frames and see for yourself is:
----
sequence <- structure(list(DATE = structure(c(14549, 14549, 14553, 14550,
14557, 14550, 14551, 14550), class = "Date"), DATASET = c(1L,
2L, 1L, 2L, 2L, 3L, 3L, 4L), REP = c(1L, 0L, 2L, 2L, 3L, 0L,
1L, 0L), WRONGS_ABS = c(0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L), WRONGS_RATIO = c(0L,
0L, 0L, 0L, 0L, 0L, 0L, 0L), DONE = c(1L, 1L, 0L, 1L, 0L, 1L,
0L, 0L)), .Names = c("DATE", "DATASET", "REP", "WRONGS_ABS",
"WRONGS_RATIO", "DONE"), class = "data.frame", row.names = c(NA,
-8L))

today.sequence <- structure(list(DATE = structure(c(14551, 14550),
class = "Date"),
    DATASET = 3:4, REP = c(1L, 0L), WRONGS_ABS = c(0L, 0L),
WRONGS_RATIO = c(0L,
    0L), DONE = c(0L, 0L)), .Names = c("DATE", "DATASET", "REP",
"WRONGS_ABS", "WRONGS_RATIO", "DONE"), row.names = 7:8, class = "data.frame")

sequence[7,] #You should see '2009-11-03       3   1          0
    0    0'

today.sequence #You can clearly see that sequence [7,] is the first
row in today.sequence

sequence[7,] %in% today.sequence #This should show 'TRUE TRUE TRUE
TRUE TRUE TRUE'.  Instead
# it shows 'FALSE FALSE FALSE FALSE FALSE FALSE'
----

Thanks
#
?"%in%" says "x" and "table" must be vectors. You supplied
data.frames. So %in% is coercing your today.sequence to a vector using

as.character(today.sequence)

Perhaps you should paste the columns together first:

x <- do.call("paste", c(sequence, sep = "::"))
table <- do.call("paste", c(today.sequence, sep = "::"))
x[7] %in% table

I'm not sure if this is what you want/need, but it does match your example.

HTH,

--sundar

On Tue, Nov 3, 2009 at 7:53 AM, Kaushik Krishnan
<kaushik.s.krishnan at gmail.com> wrote:
#
Kaushik,

The documentation doesn't quite tell (me, anyway) how the function behaves 
when 'target' is a list (or data.frame). You'll need to dig into match.c 
or experiment with match() or %in% to see what it is actually doing.

But it looks like it is matching whole columns of the data.frame rather 
than elements within each column :
[1] TRUE TRUE TRUE TRUE TRUE TRUE
[1] TRUE TRUE TRUE TRUE TRUE TRUE
[1] FALSE FALSE FALSE FALSE FALSE FALSE
[1] TRUE TRUE TRUE TRUE TRUE TRUE
Maybe you wanted something like

 	mapply( function(x,y) x%in%y , sequence[7, ], today.sequence )

??

HTH,

Chuck
On Tue, 3 Nov 2009, Kaushik Krishnan wrote:

            
Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901