R help - Sep 2008 - using complete.cases() with nested factors

Hello,

This maybe a newbie question.  I have a dataframe that looks like the sample
at the bottom of the email.  I have monthly precipitation data from several
sites over several years.  For each site, I need to extract years that have
a complete series of 12 monthly precipitation values, while excluding that
year for sites with incomplete data.  I can't figure out how to do this
gracefully (i.e. without a silly for loop).  Any help will be appreciate,
thanks!

Andrew

SiteID    year    month    precip(mm)
670090    1941    jan    2998
670090    1941    feb    1299
670090    1941    mar    1007
670090    1941    apr    354
670090    1941    may    88
670090    1941    jun    156
670090    1941    jul    8
670090    1941    aug    4
670090    1941    sep    8
670090    1941    oct    58
670090    1941    nov    397
670090    1941    dec    248
670090    1942    jan    NA
670090    1942    feb    380
670090    1942    mar    797
670090    1942    apr    142
670090    1942    may    43
670090    1942    jun    14
670090    1942    jul    70
670090    1942    aug    51
670090    1942    sep    0
670090    1942    oct    10
670090    1942    nov    235
670090    1942    dec    405

-- 
Andrew

	[[alternative HTML version deleted]]

Andrew Barr <wabarr <at> gmail.com> writes:
> This maybe a newbie question.  I have a dataframe 
that looks like the sample
> at the bottom of the email.  I have monthly 
precipitation data from several
> sites over several years.  For each site, 
I need to extract years that have
> a complete series of 12 monthly precipitation 
values, while excluding that
> year for sites with incomplete data.  
I can't figure out how to do this
> gracefully (i.e. without a silly for loop).  
Any help will be appreciate,
> thanks!
> SiteID    year    month    precip(mm)
> 670090    1941    jan    2998
> 670090    1941    feb    1299
> 670090    1941    mar    1007
> 670090    1941    apr    354
> 670090    1941    may    88
> 670090    1941    jun    156
> 670090    1941    jul    8
> 670090    1941    aug    4
> 670090    1941    sep    8
> 670090    1941    oct    58
> 670090    1941    nov    397
> 670090    1941    dec    248
> 670090    1942    jan    NA
> 670090    1942    feb    380
> 670090    1942    mar    797
> 670090    1942    apr    142
> 670090    1942    may    43
> 670090    1942    jun    14
> 670090    1942    jul    70
> 670090    1942    aug    51
> 670090    1942    sep    0
> 670090    1942    oct    10
> 670090    1942    nov    235
> 670090    1942    dec    405
> 
There are likely more elegant solutions but this seems to work.
If the data frame is in a variable named dd

lapply(unique(dd$year), function(x) {s <- subset(dd, year == x)
  if (nrow(s) == 12) s})

See ?subset and ?ave and try this:

subset(DF, ave(year, year, FUN = length) == 12)


On Thu, Sep 4, 2008 at 5:04 PM, Andrew Barr <wabarr at gmail.com>
wrote:
> Hello,
>
> This maybe a newbie question.  I have a dataframe that looks like the
sample
> at the bottom of the email.  I have monthly precipitation data from several
> sites over several years.  For each site, I need to extract years that have
> a complete series of 12 monthly precipitation values, while excluding that
> year for sites with incomplete data.  I can't figure out how to do this
> gracefully (i.e. without a silly for loop).  Any help will be appreciate,
> thanks!
>
> Andrew
>
> SiteID    year    month    precip(mm)
> 670090    1941    jan    2998
> 670090    1941    feb    1299
> 670090    1941    mar    1007
> 670090    1941    apr    354
> 670090    1941    may    88
> 670090    1941    jun    156
> 670090    1941    jul    8
> 670090    1941    aug    4
> 670090    1941    sep    8
> 670090    1941    oct    58
> 670090    1941    nov    397
> 670090    1941    dec    248
> 670090    1942    jan    NA
> 670090    1942    feb    380
> 670090    1942    mar    797
> 670090    1942    apr    142
> 670090    1942    may    43
> 670090    1942    jun    14
> 670090    1942    jul    70
> 670090    1942    aug    51
> 670090    1942    sep    0
> 670090    1942    oct    10
> 670090    1942    nov    235
> 670090    1942    dec    405
>
> --
> Andrew
>
>        [[alternative HTML version deleted]]
>
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