Re: [R] cbind giving NA's?

2011-10-24 Thread Joshua Ulrich 
Note that this issue was raised on StackOverflow recently.
http://stackoverflow.com/questions/7678090/xts-merge-odd-behaviour

Here's the solution:

index(a) - index(a)
index(b) - index(b)
merge(a,b)
   ZWD.UGX SCHB.Close
2010-03-31  NA  28.02
2010-04-01  7.6343 NA
2010-04-02  7.6343 NA
2010-04-03  7.5458 NA
2010-04-04  7.4532  28.30
2010-04-05  7.4040  28.38
2010-04-06  7.3317  28.21
2010-04-07  NA  28.31
2010-04-08  NA  28.47

Jeff's answer on StackOverflow explains why this works.

Best,
--
Joshua Ulrich  |  FOSS Trading: www.fosstrading.com



On Fri, Aug 26, 2011 at 8:09 AM, R. Michael Weylandt
michael.weyla...@gmail.com wrote:
 This seems to be the easiest way to handle the problem:

 a = xts(coredata(a), time(a))
 b = xts(coredata(b), time(b))
 merge(a,b)


           ZWD.UGX SCHB.Close
 2010-03-31      NA      28.02
 2010-04-01  7.6343         NA
 2010-04-02  7.6343         NA
 2010-04-03  7.5458         NA
 2010-04-04  7.4532      28.30
 2010-04-05  7.4040      28.38
 2010-04-06  7.3317      28.21
 2010-04-07      NA      28.31
 2010-04-08      NA      28.47

 I can't be sure where the problem was coming from, but if you look
 closely into the mumbo jumbo of the dput() code you'll see that the
 time indices don't actually match anywhere as POSIXct/POSIXt objects.
 Even though they map to the same day, something or other is keeping
 them as internally different and it's probably inherited from the data
 sources -- one set maps to times captured at 2300 EDT on my machine
 and the other to 0800 EDT. If you want, it might be interesting to
 track down the difference, but the fix I gave above, which basically
 pulls the time data out through the xts class and only keeps the date
 in creating a new xts that's exactly the same should handle it.

 In short, it's all black magic derived from R's various time/date
 mechanisms. If you don't


 really want to see whats under the hood, this will also work in this case.


 a = as.xts(a)
 b = as.xts(b)
 merge(a, b)

 But this can lead to some strange code if you don't take a moment to think
 about it

 is.xts(a)
 TRUE

 identical(a, as.xts(a))
 FALSE

 Hope this helps and thanks for the fun problem!

 Michael Weylandt




 On Fri, Aug 26, 2011 at 8:08 AM, Petr PIKAL petr.pi...@precheza.cz wrote:

 I was rather too quick

 It has probably something to do with versions of zoo and xts

 after updating to zoo 1.7.4 and xts 0.8.2 I got with your examples

  merge(a,b)
           ZWD.UGX SCHB.Close
 2010-04-01      NA      28.02
 2010-04-01  7.6343         NA
 2010-04-02  7.6343         NA
 2010-04-03  7.5458         NA
 2010-04-04  7.4532         NA
 2010-04-05      NA      28.30
 2010-04-05  7.4040         NA
 2010-04-06      NA      28.38
 2010-04-06  7.3317         NA
 2010-04-07      NA      28.21
 2010-04-08      NA      28.31
 2010-04-09      NA      28.47

 but when I did

  a-as.zoo(a)
  b-as.zoo(b)

 I got

  merge(a,b)
           ZWD.UGX SCHB.Close
 2010-04-01  7.6343      28.02
 2010-04-02  7.6343         NA
 2010-04-03  7.5458         NA
 2010-04-04  7.4532         NA
 2010-04-05  7.4040      28.30
 2010-04-06  7.3317      28.38
 2010-04-07      NA      28.21
 2010-04-08      NA      28.31
 2010-04-09      NA      28.47

 which is probably what you want.

 Regards
 Petr

 

  Hi
 
  
   On 26 August 2011 03:37, R. Michael Weylandt
 michael.weyla...@gmail.com wrote:
If you could, dput() them so we can see everything about them. You
 also
might see if merge() gives you more expected behavior
  
   Ok...
dput(a)
   structure(c(7.6343, 7.6343, 7.5458, 7.4532, 7.404, 7.3317), class =
 c(xts,
   zoo), .indexCLASS = Date, .indexTZ = , index =
 structure(c(1270105200,
   1270191600, 1270278000, 1270364400, 1270450800, 1270537200), tzone =
   , tclass = Date), .Dim = c(6L,
   1L), .Dimnames = list(NULL, ZWD.UGX))
dput(b)
   structure(c(28.02, 28.3, 28.38, 28.21, 28.31, 28.47), .indexCLASS =
   Date, .indexTZ = , src = yahoo, updated =
   structure(1314356091.21457, class = c(POSIXct,
   POSIXt)), class = c(xts, zoo), index = structure(c(1270072800,
   1270418400, 1270504800, 1270591200, 1270677600, 1270764000), tzone =
   , tclass = Date), .Dim = c(6L,
   1L), .Dimnames = list(NULL, SCHB.Close))
merge(a,b)
merge(a,b)
              ZWD.UGX SCHB.Close
   2010-04-01      NA      28.02
   2010-04-01  7.6343         NA
   2010-04-02  7.6343         NA
   2010-04-03  7.5458         NA
   2010-04-04  7.4532         NA
   2010-04-05      NA      28.30
   2010-04-05  7.4040         NA
   2010-04-06      NA      28.38
   2010-04-06  7.3317         NA
   2010-04-07      NA      28.21
   2010-04-08      NA      28.31
   2010-04-09      NA      28.47
q()

  I get slightly different result
 
   xx-(merge(a,b))
   xx
             ZWD.UGX SCHB.Close
  1270072800      NA      28.02
  1270105200  7.6343         NA
  1270191600  7.6343         NA
  1270278000  7.5458         NA

[R] cbind giving NA's?

2011-08-26 Thread Hasan Diwan 
I have two xts objects, call them a and b, and am trying to merge them...
 class(a)
[1] xts zoo
 class(b)
[1] xts zoo
 head(a)
2010-04-01  7.6343
2010-04-02  7.6343
2010-04-03  7.5458
2010-04-04  7.4532
2010-04-05  7.4040
2010-04-06  7.3317
 head(b)
2010-04-01 568.80
2010-04-05 571.01
2010-04-06 568.22
2010-04-07 563.54
2010-04-08 567.49
2010-04-09 566.22
 head(cbind(a,b))
2010-04-01 568.80  NA
2010-04-01 NA  0.3998
2010-04-02 NA  0.3998
2010-04-03 NA  0.3999
2010-04-04 NA  0.3994
2010-04-05 571.01  NA
 q()
I'd like the cbind'ed version to look like:
2010-04-01 568.800.3998
2010-04-02 NA  0.3998
2010-04-03 NA  0.3999
2010-04-04 NA  0.3994
2010-04-05 571.01  0.3991

What gives? Many thanks, in advance. -- H

-- 
Sent from my mobile device
Envoyait de mon telephone mobil

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Re: [R] cbind giving NA's?

2011-08-26 Thread R. Michael Weylandt 
Hmm, that's quite puzzling. I don't know but I'd willing to guess the
time/date stamps on a,b are more different than the output is leading us to
believe. My experience is that there's always more to a time/date object to
trick us up than one would expect.

If you could, dput() them so we can see everything about them. You also
might see if merge() gives you more expected behavior

Michael Weylandt


On Fri, Aug 26, 2011 at 6:05 AM, Hasan Diwan hasan.di...@gmail.com wrote:

 I have two xts objects, call them a and b, and am trying to merge
 them...
  class(a)
 [1] xts zoo
  class(b)
 [1] xts zoo
  head(a)
 2010-04-01  7.6343
 2010-04-02  7.6343
 2010-04-03  7.5458
 2010-04-04  7.4532
 2010-04-05  7.4040
 2010-04-06  7.3317
  head(b)
 2010-04-01 568.80
 2010-04-05 571.01
 2010-04-06 568.22
 2010-04-07 563.54
 2010-04-08 567.49
 2010-04-09 566.22
  head(cbind(a,b))
 2010-04-01 568.80  NA
 2010-04-01 NA  0.3998
 2010-04-02 NA  0.3998
 2010-04-03 NA  0.3999
 2010-04-04 NA  0.3994
 2010-04-05 571.01  NA
  q()
 I'd like the cbind'ed version to look like:
 2010-04-01 568.800.3998
 2010-04-02 NA  0.3998
 2010-04-03 NA  0.3999
 2010-04-04 NA  0.3994
 2010-04-05 571.01  0.3991

 What gives? Many thanks, in advance. -- H

 --
 Sent from my mobile device
 Envoyait de mon telephone mobil

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Re: [R] cbind giving NA's?

2011-08-26 Thread Hasan Diwan 
On 26 August 2011 03:37, R. Michael Weylandt michael.weyla...@gmail.com wrote:
 If you could, dput() them so we can see everything about them. You also
 might see if merge() gives you more expected behavior

Ok...
 dput(a)
structure(c(7.6343, 7.6343, 7.5458, 7.4532, 7.404, 7.3317), class = c(xts,
zoo), .indexCLASS = Date, .indexTZ = , index = structure(c(1270105200,
1270191600, 1270278000, 1270364400, 1270450800, 1270537200), tzone =
, tclass = Date), .Dim = c(6L,
1L), .Dimnames = list(NULL, ZWD.UGX))
 dput(b)
structure(c(28.02, 28.3, 28.38, 28.21, 28.31, 28.47), .indexCLASS =
Date, .indexTZ = , src = yahoo, updated =
structure(1314356091.21457, class = c(POSIXct,
POSIXt)), class = c(xts, zoo), index = structure(c(1270072800,
1270418400, 1270504800, 1270591200, 1270677600, 1270764000), tzone =
, tclass = Date), .Dim = c(6L,
1L), .Dimnames = list(NULL, SCHB.Close))
 merge(a,b)
 merge(a,b)
   ZWD.UGX SCHB.Close
2010-04-01  NA  28.02
2010-04-01  7.6343 NA
2010-04-02  7.6343 NA
2010-04-03  7.5458 NA
2010-04-04  7.4532 NA
2010-04-05  NA  28.30
2010-04-05  7.4040 NA
2010-04-06  NA  28.38
2010-04-06  7.3317 NA
2010-04-07  NA  28.21
2010-04-08  NA  28.31
2010-04-09  NA  28.47
 q()

So, no, merge doesn't work...
-- 
Sent from my mobile device
Envoyait de mon telephone mobil

__
R-help@r-project.org mailing list
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and provide commented, minimal, self-contained, reproducible code.

Re: [R] cbind giving NA's?

2011-08-26 Thread Petr PIKAL 
Hi

 
 On 26 August 2011 03:37, R. Michael Weylandt 
michael.weyla...@gmail.com wrote:
  If you could, dput() them so we can see everything about them. You 
also
  might see if merge() gives you more expected behavior
 
 Ok...
  dput(a)
 structure(c(7.6343, 7.6343, 7.5458, 7.4532, 7.404, 7.3317), class = 
c(xts,
 zoo), .indexCLASS = Date, .indexTZ = , index = 
structure(c(1270105200,
 1270191600, 1270278000, 1270364400, 1270450800, 1270537200), tzone =
 , tclass = Date), .Dim = c(6L,
 1L), .Dimnames = list(NULL, ZWD.UGX))
  dput(b)
 structure(c(28.02, 28.3, 28.38, 28.21, 28.31, 28.47), .indexCLASS =
 Date, .indexTZ = , src = yahoo, updated =
 structure(1314356091.21457, class = c(POSIXct,
 POSIXt)), class = c(xts, zoo), index = structure(c(1270072800,
 1270418400, 1270504800, 1270591200, 1270677600, 1270764000), tzone =
 , tclass = Date), .Dim = c(6L,
 1L), .Dimnames = list(NULL, SCHB.Close))
  merge(a,b)
  merge(a,b)
ZWD.UGX SCHB.Close
 2010-04-01  NA  28.02
 2010-04-01  7.6343 NA
 2010-04-02  7.6343 NA
 2010-04-03  7.5458 NA
 2010-04-04  7.4532 NA
 2010-04-05  NA  28.30
 2010-04-05  7.4040 NA
 2010-04-06  NA  28.38
 2010-04-06  7.3317 NA
 2010-04-07  NA  28.21
 2010-04-08  NA  28.31
 2010-04-09  NA  28.47
  q()

I get slightly different result

 xx-(merge(a,b))
 xx
   ZWD.UGX SCHB.Close
1270072800  NA  28.02
1270105200  7.6343 NA
1270191600  7.6343 NA
1270278000  7.5458 NA
1270364400  7.4532 NA
1270418400  NA  28.30
1270450800  7.4040 NA
1270504800  NA  28.38
1270537200  7.3317 NA
1270591200  NA  28.21
1270677600  NA  28.31
1270764000  NA  28.47

but from what you want it seems to me that aggregate could be suitable 
second step.

something like

aggregate(xx, list(those dates you have but I don't), mean, na.rm=T)

could do what you want.

Regards
Petr



 
 So, no, merge doesn't work...
 -- 
 Sent from my mobile device
 Envoyait de mon telephone mobil
 
 __
 R-help@r-project.org mailing list
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 PLEASE do read the posting guide 
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Re: [R] cbind giving NA's?

2011-08-26 Thread Dennis Murphy 
Hi:

Try this:

require('xts')
 merge.zoo(zoo(a), zoo(b), all = c(TRUE, TRUE))
   ZWD.UGX SCHB.Close
2010-03-31  NA  28.02
2010-04-01  7.6343 NA
2010-04-02  7.6343 NA
2010-04-03  7.5458 NA
2010-04-04  7.4532  28.30
2010-04-05  7.4040  28.38
2010-04-06  7.3317  28.21
2010-04-07  NA  28.31
2010-04-08  NA  28.47

HTH,
Dennis

On Fri, Aug 26, 2011 at 3:58 AM, Hasan Diwan hasan.di...@gmail.com wrote:
 On 26 August 2011 03:37, R. Michael Weylandt michael.weyla...@gmail.com 
 wrote:
 If you could, dput() them so we can see everything about them. You also
 might see if merge() gives you more expected behavior

 Ok...
 dput(a)
 structure(c(7.6343, 7.6343, 7.5458, 7.4532, 7.404, 7.3317), class = c(xts,
 zoo), .indexCLASS = Date, .indexTZ = , index = structure(c(1270105200,
 1270191600, 1270278000, 1270364400, 1270450800, 1270537200), tzone =
 , tclass = Date), .Dim = c(6L,
 1L), .Dimnames = list(NULL, ZWD.UGX))
 dput(b)
 structure(c(28.02, 28.3, 28.38, 28.21, 28.31, 28.47), .indexCLASS =
 Date, .indexTZ = , src = yahoo, updated =
 structure(1314356091.21457, class = c(POSIXct,
 POSIXt)), class = c(xts, zoo), index = structure(c(1270072800,
 1270418400, 1270504800, 1270591200, 1270677600, 1270764000), tzone =
 , tclass = Date), .Dim = c(6L,
 1L), .Dimnames = list(NULL, SCHB.Close))
 merge(a,b)
 merge(a,b)
           ZWD.UGX SCHB.Close
 2010-04-01      NA      28.02
 2010-04-01  7.6343         NA
 2010-04-02  7.6343         NA
 2010-04-03  7.5458         NA
 2010-04-04  7.4532         NA
 2010-04-05      NA      28.30
 2010-04-05  7.4040         NA
 2010-04-06      NA      28.38
 2010-04-06  7.3317         NA
 2010-04-07      NA      28.21
 2010-04-08      NA      28.31
 2010-04-09      NA      28.47
 q()

 So, no, merge doesn't work...
 --
 Sent from my mobile device
 Envoyait de mon telephone mobil

 __
 R-help@r-project.org mailing list
 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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Re: [R] cbind giving NA's?

2011-08-26 Thread Petr PIKAL 
I was rather too quick

It has probably something to do with versions of zoo and xts

after updating to zoo 1.7.4 and xts 0.8.2 I got with your examples

 merge(a,b)
   ZWD.UGX SCHB.Close
2010-04-01  NA  28.02
2010-04-01  7.6343 NA
2010-04-02  7.6343 NA
2010-04-03  7.5458 NA
2010-04-04  7.4532 NA
2010-04-05  NA  28.30
2010-04-05  7.4040 NA
2010-04-06  NA  28.38
2010-04-06  7.3317 NA
2010-04-07  NA  28.21
2010-04-08  NA  28.31
2010-04-09  NA  28.47

but when I did

 a-as.zoo(a)
 b-as.zoo(b)

I got

 merge(a,b)
   ZWD.UGX SCHB.Close
2010-04-01  7.6343  28.02
2010-04-02  7.6343 NA
2010-04-03  7.5458 NA
2010-04-04  7.4532 NA
2010-04-05  7.4040  28.30
2010-04-06  7.3317  28.38
2010-04-07  NA  28.21
2010-04-08  NA  28.31
2010-04-09  NA  28.47

which is probably what you want.

Regards
Petr

 

 Hi
 
  
  On 26 August 2011 03:37, R. Michael Weylandt 
michael.weyla...@gmail.com wrote:
   If you could, dput() them so we can see everything about them. You 
also
   might see if merge() gives you more expected behavior
  
  Ok...
   dput(a)
  structure(c(7.6343, 7.6343, 7.5458, 7.4532, 7.404, 7.3317), class = 
c(xts,
  zoo), .indexCLASS = Date, .indexTZ = , index = 
structure(c(1270105200,
  1270191600, 1270278000, 1270364400, 1270450800, 1270537200), tzone =
  , tclass = Date), .Dim = c(6L,
  1L), .Dimnames = list(NULL, ZWD.UGX))
   dput(b)
  structure(c(28.02, 28.3, 28.38, 28.21, 28.31, 28.47), .indexCLASS =
  Date, .indexTZ = , src = yahoo, updated =
  structure(1314356091.21457, class = c(POSIXct,
  POSIXt)), class = c(xts, zoo), index = structure(c(1270072800,
  1270418400, 1270504800, 1270591200, 1270677600, 1270764000), tzone =
  , tclass = Date), .Dim = c(6L,
  1L), .Dimnames = list(NULL, SCHB.Close))
   merge(a,b)
   merge(a,b)
 ZWD.UGX SCHB.Close
  2010-04-01  NA  28.02
  2010-04-01  7.6343 NA
  2010-04-02  7.6343 NA
  2010-04-03  7.5458 NA
  2010-04-04  7.4532 NA
  2010-04-05  NA  28.30
  2010-04-05  7.4040 NA
  2010-04-06  NA  28.38
  2010-04-06  7.3317 NA
  2010-04-07  NA  28.21
  2010-04-08  NA  28.31
  2010-04-09  NA  28.47
   q()

 I get slightly different result
 
  xx-(merge(a,b))
  xx
ZWD.UGX SCHB.Close
 1270072800  NA  28.02
 1270105200  7.6343 NA
 1270191600  7.6343 NA
 1270278000  7.5458 NA
 1270364400  7.4532 NA
 1270418400  NA  28.30
 1270450800  7.4040 NA
 1270504800  NA  28.38
 1270537200  7.3317 NA
 1270591200  NA  28.21
 1270677600  NA  28.31
 1270764000  NA  28.47
 
 but from what you want it seems to me that aggregate could be suitable 
second step.
 
 something like
 
 aggregate(xx, list(those dates you have but I don't), mean, na.rm=T)
 
 could do what you want.
 
 Regards
 Petr
 
  
  So, no, merge doesn't work...
  -- 
  Sent from my mobile device
  Envoyait de mon telephone mobil
  
  __
  R-help@r-project.org mailing list
  https://stat.ethz.ch/mailman/listinfo/r-help
  PLEASE do read the posting guide 
http://www.R-project.org/posting-guide.html
  and provide commented, minimal, self-contained, reproducible code.

__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Re: [R] cbind giving NA's?

2011-08-26 Thread R. Michael Weylandt 
This seems to be the easiest way to handle the problem:

 a = xts(coredata(a), time(a))
 b = xts(coredata(b), time(b))
 merge(a,b)


   ZWD.UGX SCHB.Close
2010-03-31  NA  28.02
2010-04-01  7.6343 NA
2010-04-02  7.6343 NA
2010-04-03  7.5458 NA
2010-04-04  7.4532  28.30
2010-04-05  7.4040  28.38
2010-04-06  7.3317  28.21
2010-04-07  NA  28.31
2010-04-08  NA  28.47

I can't be sure where the problem was coming from, but if you look
closely into the mumbo jumbo of the dput() code you'll see that the
time indices don't actually match anywhere as POSIXct/POSIXt objects.
Even though they map to the same day, something or other is keeping
them as internally different and it's probably inherited from the data
sources -- one set maps to times captured at 2300 EDT on my machine
and the other to 0800 EDT. If you want, it might be interesting to
track down the difference, but the fix I gave above, which basically
pulls the time data out through the xts class and only keeps the date
in creating a new xts that's exactly the same should handle it.

In short, it's all black magic derived from R's various time/date
mechanisms. If you don't


really want to see whats under the hood, this will also work in this case.


 a = as.xts(a)
 b = as.xts(b)
 merge(a, b)

But this can lead to some strange code if you don't take a moment to think
about it

 is.xts(a)
TRUE

 identical(a, as.xts(a))
FALSE

Hope this helps and thanks for the fun problem!

Michael Weylandt




On Fri, Aug 26, 2011 at 8:08 AM, Petr PIKAL petr.pi...@precheza.cz wrote:

 I was rather too quick

 It has probably something to do with versions of zoo and xts

 after updating to zoo 1.7.4 and xts 0.8.2 I got with your examples

  merge(a,b)
   ZWD.UGX SCHB.Close
 2010-04-01  NA  28.02
 2010-04-01  7.6343 NA
 2010-04-02  7.6343 NA
 2010-04-03  7.5458 NA
 2010-04-04  7.4532 NA
 2010-04-05  NA  28.30
 2010-04-05  7.4040 NA
 2010-04-06  NA  28.38
 2010-04-06  7.3317 NA
 2010-04-07  NA  28.21
 2010-04-08  NA  28.31
 2010-04-09  NA  28.47

 but when I did

  a-as.zoo(a)
  b-as.zoo(b)

 I got

  merge(a,b)
   ZWD.UGX SCHB.Close
 2010-04-01  7.6343  28.02
 2010-04-02  7.6343 NA
 2010-04-03  7.5458 NA
 2010-04-04  7.4532 NA
 2010-04-05  7.4040  28.30
 2010-04-06  7.3317  28.38
 2010-04-07  NA  28.21
 2010-04-08  NA  28.31
 2010-04-09  NA  28.47

 which is probably what you want.

 Regards
 Petr

 

  Hi
 
  
   On 26 August 2011 03:37, R. Michael Weylandt
 michael.weyla...@gmail.com wrote:
If you could, dput() them so we can see everything about them. You
 also
might see if merge() gives you more expected behavior
  
   Ok...
dput(a)
   structure(c(7.6343, 7.6343, 7.5458, 7.4532, 7.404, 7.3317), class =
 c(xts,
   zoo), .indexCLASS = Date, .indexTZ = , index =
 structure(c(1270105200,
   1270191600, 1270278000, 1270364400, 1270450800, 1270537200), tzone =
   , tclass = Date), .Dim = c(6L,
   1L), .Dimnames = list(NULL, ZWD.UGX))
dput(b)
   structure(c(28.02, 28.3, 28.38, 28.21, 28.31, 28.47), .indexCLASS =
   Date, .indexTZ = , src = yahoo, updated =
   structure(1314356091.21457, class = c(POSIXct,
   POSIXt)), class = c(xts, zoo), index = structure(c(1270072800,
   1270418400, 1270504800, 1270591200, 1270677600, 1270764000), tzone =
   , tclass = Date), .Dim = c(6L,
   1L), .Dimnames = list(NULL, SCHB.Close))
merge(a,b)
merge(a,b)
  ZWD.UGX SCHB.Close
   2010-04-01  NA  28.02
   2010-04-01  7.6343 NA
   2010-04-02  7.6343 NA
   2010-04-03  7.5458 NA
   2010-04-04  7.4532 NA
   2010-04-05  NA  28.30
   2010-04-05  7.4040 NA
   2010-04-06  NA  28.38
   2010-04-06  7.3317 NA
   2010-04-07  NA  28.21
   2010-04-08  NA  28.31
   2010-04-09  NA  28.47
q()

  I get slightly different result
 
   xx-(merge(a,b))
   xx
 ZWD.UGX SCHB.Close
  1270072800  NA  28.02
  1270105200  7.6343 NA
  1270191600  7.6343 NA
  1270278000  7.5458 NA
  1270364400  7.4532 NA
  1270418400  NA  28.30
  1270450800  7.4040 NA
  1270504800  NA  28.38
  1270537200  7.3317 NA
  1270591200  NA  28.21
  1270677600  NA  28.31
  1270764000  NA  28.47
 
  but from what you want it seems to me that aggregate could be suitable
 second step.
 
  something like
 
  aggregate(xx, list(those dates you have but I don't), mean, na.rm=T)
 
  could do what you want.
 
  Regards
  Petr
 
  
   So, no, merge doesn't work...
   --
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