Sorry...I was unaware I needed to 'deput' to deparse data examples into a
useful format. The data examples I provided initially are deparsed below:
df1<-
list(ID = c(2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3), Date = c("2007-05-30
18:48:20",
"2007-05-30 20:21:56", "2007-06-02 09:39:58", "2007-06-02 17:36:20",
"2007-06-03 20:31:35", "2007-06-05 08:34:37", "2007-02-19 00:00:00",
"2007-03-10 19:58:18", "2007-03-23 06:33:26", "2007-03-23 17:02:21",
"2007-03-24 04:27:44", "2007-03-24 11:35:47", "2007-03-25 06:41:03"
), y = c(NA, NA, -20.101, NA, NA, NA, -37.4082166666667, NA,
NA, NA, -31.164, NA, -31.181), x = c(NA, NA, -134.421, NA, NA,
NA, 178.34395, NA, NA, NA, 178.765, NA, 178.77))
df2<-
list(ID = c(1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2), Date = c("2007-05-31
23:00:00",
"2007-06-01 11:00:00", "2007-06-01 23:00:00", "2007-02-19 00:00:00",
"2007-02-19 12:00:00", "2007-02-20 00:00:00", "2007-02-20 12:00:00",
"2007-02-21 00:00:00", "2007-02-21 12:00:00", "2007-02-22 00:00:00",
"2007-02-22 12:00:00", "2007-02-23 00:00:00", "2007-02-23 12:00:00"
), y = c(-20.829075, -20.824995, -20.822355, -37.4096, -37.37515,
-37.277, -37.17855, -37.07595, -36.91965, -36.74345, -36.49245,
-36.2415, -35.955), x = c(217.7022, 217.698, 217.70115, 178.306,
178.336, 178.378, 178.3845, 178.389, 178.3965, 178.391, 178.509,
178.575, 178.628))
On Sun, Dec 28, 2008 at 4:36 PM, Tim Sippel <tsip...@gmail.com> wrote:
> Hi-
> I have two data frames for which I wish to conditionally subtract the
> values of one dataframe from the other.
>
> I want to subtract df1$x from df2$x when their id is equal and the
> absolute value of difference between the dates is 12 hours or less. If
> there is no match of equal id's and dates less than 12 hours apart I want it
> to return "NA". Note that df1 has missing values in x and y columns, but
> df2 does not have any missing values. I think I'm close with the code at
> the end, but would appreciate a bit of help getting over this hurdle.
>
> Sample dataframes follow:
>
> *df1<-*
> ID Date y x STM07.1 30-05-2007 18:48 STM07.1 30-05-2007 20:21
> STM07.1 02-06-2007 09:39 -20.101 -134.421 STM07.1 02-06-2007 17:36
> STM07.1 03-06-2007 20:31 STM07.1 05-06-2007 08:34 STM07.2 19-02-2007
> 00:00 -37.4082 178.34395 STM07.2 10-03-2007 19:58 STM07.2 23-03-2007
> 06:33 STM07.2 23-03-2007 17:02 STM07.2 24-03-2007 04:27 -31.164 178.765
> STM07.2 24-03-2007 11:35 STM07.2 25-03-2007 06:41 -31.181 178.77 STM07.2
> 26-03-2007
> 05:11
> **
> *df2<-*
> ID Date y x STM07.1 31/05/2007 23:00 -20.8291 217.7022 STM07.1 1/06/2007
> 11:00 -20.825 217.698 STM07.1 1/06/2007 23:00 -20.8224 217.70115 STM07.2
> 19/02/2007
> 0:00 -37.4096 178.306 STM07.2 19/02/2007 12:00 -37.3752 178.336 STM07.2
> 20/02/2007
> 0:00 -37.277 178.378 STM07.2 20/02/2007 12:00 -37.1786 178.3845 STM07.2
> 21/02/2007
> 0:00 -37.076 178.389 STM07.2 21/02/2007 12:00 -36.9197 178.3965 STM07.2
> 22/02/2007
> 0:00 -36.7435 178.391 STM07.2 22/02/2007 12:00 -36.4925 178.509 STM07.2
> 23/02/2007
> 0:00 -36.2415 178.575 STM07.2 23/02/2007 12:00 -35.955 178.628
>
> d.x <- ifelse(c(test = df1$ID==df2$ID && abs(difftime(as.POSIXlt(df1$Date),
> as.POSIXlt(df2$Date),
> units="hours") < 12)), yes = delta.lon=df1$x-df2$x, no = "NA")
>
> I'm using R 2.7.1.
>
> Cheers,
>
> Tim
>
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