Message-ID: <f8e6ff050904301515s32f0ec35le4f251dbc8c4ee6e@mail.gmail.com>
Date: 2009-04-30T22:15:55Z
From: Hadley Wickham
Subject: gridding values in a data frame
In-Reply-To: <23319190.post@talk.nabble.com>
It's hard to check without a reproducible example, but the following
code should give you a 3d array of lat x long x time:
library(reshape)
df$lat <- round_any(df$LATITUDE, 5)
df$long <- round_any(df$LONGITUDE, 5)
df$value <- df$TIME
cast(df, lat ~ long ~ time, mean)
On Thu, Apr 30, 2009 at 10:55 AM, dxc13 <dxc13 at health.state.ny.us> wrote:
>
> Hi all,
> I have a data frame that looks like such:
> LATITUDE ? LONGITUDE ? TEMPERATURE ? TIME
> 36.73 ? ? ? ? -176.43 ? ? ? ?58.32 ? ? ? ? ? ? ? 1
> 50.95 ? ? ? ? ? ?90.00 ? ? ? ?74.39 ? ? ? ? ? ? ? 1
> -30.42 ? ? ? ? ? ?5.45 ? ? ? ?23.26 ? ? ? ? ? ? ? 1
> 15.81 ? ? ? ? -109.31 ? ? ? ?52.44 ? ? ? ? ? ? ? 1
> -80.75 ? ? ? ?-144.95 ? ? ? ?66.19 ? ? ? ? ? ? ?2
> 90.00 ? ? ? ? ?100.55 ? ? ? ?37.50 ? ? ? ? ? ? ? 2
> 65.41 ? ? ? ? -4.49 ? ? ? ? ? 29.83 ? ? ? ? ? ? ? 2
>
> and this goes on for a A LOT more records, until time=1200
>
> I want to create a 5 degree by 5 degree grid of this data, with the value of
> temperature in the appropriate grid cell. ?I want one grid for each time
> value. ?For each time value, this works out to be a 36x72 grid with 2592
> cells because the longitude spans -180 to 180 and latitude spans 90 to -90
> and they would be in increments of 5 degrees. ?If there are no temperatures
> available to be put into a grid cell, than that cell should get a missing
> value, NA, put into it.
> Also, could the gridded result for each time be written to a text file
> before processing the next time value?
>
> Hope this is clear.
> Thanks in advance.
>
> dxc13
> --
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>
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>
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