R help - Apr 2012 - subset daily to monthly in a zoo or xts

Dear R users,

I want to subset a daily zoo series according to its month, find % of
"NA"
in each month.

I am finding it difficult to subset the daily dataset into monthly for the
given operation.I am planning to do this for a huge dataset.

Thanks in advance.

Regards
Vikram

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On Mon, 23 Apr 2012, Vikram Bahure wrote:
> Dear R users,
>
> I want to subset a daily zoo series according to its month, find % of
"NA"
> in each month.
>
> I am finding it difficult to subset the daily dataset into monthly for the
> given operation.I am planning to do this for a huge dataset.
Use aggregate(z, as.yearmon, ...) for aggregation to a monthly series. A 
simple artificial example is:

## data with NAs
set.seed(1)
x <- rnorm(50)
x[sample(1:50, 10)] <- NA

## as zoo
z <- zoo(x, as.Date("2012-01-01") + 0:49)

## proportion of NAs
aggregate(z, as.yearmon, function(x) mean(is.na(x)))

hth,
Z
> Thanks in advance.
>
> Regards
> Vikram
>
> 	[[alternative HTML version deleted]]
>
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Hi Vikram,

maybe something like this?

require("zoo")

## a daily zoo series
z <- zoo(1:200, as.Date("2012-01-01") + 1:200)

## add some NAs
z[ceiling(runif(10)*200)] <- NA

## aggregate to monthly
aggregate(z, format(index(z), "%Y-%m"), length)
aggregate(z, format(index(z), "%Y-%m"), function(x) sum(is.na(x)))
aggregate(z, format(index(z), "%Y-%m"), function(x)
sum(is.na(x))/length(x))



Regards,
Enrico

Am 23.04.2012 11:27, schrieb Vikram Bahure:
> Dear R users,
>
> I want to subset a daily zoo series according to its month, find % of
> "NA" in each month.
>
> I am finding it difficult to subset the daily dataset into monthly
> for the given operation.I am planning to do this for a huge dataset.
>
> Thanks in advance.
>
> Regards Vikram
>
>
-- 
Enrico Schumann
Lucerne, Switzerland
http://nmof.net