

I have a table that looks like this:
structure(list(speed = c(3,9,4,8,7,6), C = c(0.697, 0.011, 0.015, 0.012, 0.018, 0.019), house = c(1,
1, 1, 1, 1, 1), date = c(719, 1027, 1027, 1027, 1030, 1030),
hour = c(18, 8, 8, 8, 11, 11), id = c("1000", "10000",
"10001", "10002", "10003", "10004")), .Names = c("speed",
"C", "house", "date", "hour", "id"), class = "data.frame", row.names = c("1000",
"10000", "10001", "10002", "10003", "10004"))
I want to determine the minimum speed for each date, and the C that corresponds to that lowest speed.Then I want to make a table that contains all speeds and the difference between C and the lowest C.
For example, on the date 1027, the minimum speed is 4 and the C that corresponds to that is 0.015. The new table should contain:
speed 8 and C 0.003
speed 9 and C 0.004
speed 7 and C 0.001How do you do this?
Thanks,
Jeffrey
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I'd dont quite get what you are asking, but here's my best guess and
you can tweak it go get what you need.
I'd do it in two passes since you want two rather unrelated objects.
structure(list(speed = c(3,9,4,8,7,6), C = c(0.697, 0.011, 0.015,
0.012, 0.018, 0.019), house = c(1,
1, 1, 1, 1, 1), date = c(719, 1027, 1027, 1027, 1030, 1030),
hour = c(18, 8, 8, 8, 11, 11), id = c("1000", "10000",
"10001", "10002", "10003", "10004")), .Names = c("speed",
"C", "house", "date", "hour", "id"), class = "data.frame", row.names = c("1000",
"10000", "10001", "10002", "10003", "10004")) > X
tapply(X, X$date, function(d) d$speed  min(d$speed))
tapply(X, X$date, function(d) d$C[which.min(d$speed)])
Michael
On Thu, Oct 20, 2011 at 5:56 PM, Jeffrey Joh < [hidden email]> wrote:
>
> I have a table that looks like this:
>
> structure(list(speed = c(3,9,4,8,7,6), C = c(0.697, 0.011, 0.015, 0.012, 0.018, 0.019), house = c(1,
> 1, 1, 1, 1, 1), date = c(719, 1027, 1027, 1027, 1030, 1030),
> hour = c(18, 8, 8, 8, 11, 11), id = c("1000", "10000",
> "10001", "10002", "10003", "10004")), .Names = c("speed",
> "C", "house", "date", "hour", "id"), class = "data.frame", row.names = c("1000",
> "10000", "10001", "10002", "10003", "10004"))
>
> I want to determine the minimum speed for each date, and the C that corresponds to that lowest speed.Then I want to make a table that contains all speeds and the difference between C and the lowest C.
>
> For example, on the date 1027, the minimum speed is 4 and the C that corresponds to that is 0.015. The new table should contain:
> speed 8 and C 0.003
> speed 9 and C 0.004
> speed 7 and C 0.001How do you do this?
>
> Thanks,
> Jeffrey
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] mailing list
> https://stat.ethz.ch/mailman/listinfo/rhelp> PLEASE do read the posting guide http://www.Rproject.org/postingguide.html> and provide commented, minimal, selfcontained, reproducible code.
>
______________________________________________
[hidden email] mailing list
https://stat.ethz.ch/mailman/listinfo/rhelpPLEASE do read the posting guide http://www.Rproject.org/postingguide.htmland provide commented, minimal, selfcontained, reproducible code.


Hi:
Here's one way with the plyr package. Using ds as the name of your
data frame (thank you for the dput and clear description of what you
wanted, BTW),
library('plyr')
ddply(ds, .(date), mutate, minspd = min(speed), Cmin =
C[which.min(speed)], diff = C  Cmin)
speed C house date hour id minspd Cmin diff
1 3 0.697 1 719 18 1000 3 0.697 0.000
2 9 0.011 1 1027 8 10000 4 0.015 0.004
3 4 0.015 1 1027 8 10001 4 0.015 0.000
4 8 0.012 1 1027 8 10002 4 0.015 0.003
5 7 0.018 1 1030 11 10003 6 0.019 0.001
6 6 0.019 1 1030 11 10004 6 0.019 0.000
HTH,
Dennis
On Thu, Oct 20, 2011 at 2:56 PM, Jeffrey Joh < [hidden email]> wrote:
>
> I have a table that looks like this:
>
> structure(list(speed = c(3,9,4,8,7,6), C = c(0.697, 0.011, 0.015, 0.012, 0.018, 0.019), house = c(1,
> 1, 1, 1, 1, 1), date = c(719, 1027, 1027, 1027, 1030, 1030),
> hour = c(18, 8, 8, 8, 11, 11), id = c("1000", "10000",
> "10001", "10002", "10003", "10004")), .Names = c("speed",
> "C", "house", "date", "hour", "id"), class = "data.frame", row.names = c("1000",
> "10000", "10001", "10002", "10003", "10004"))
>
> I want to determine the minimum speed for each date, and the C that corresponds to that lowest speed.Then I want to make a table that contains all speeds and the difference between C and the lowest C.
>
> For example, on the date 1027, the minimum speed is 4 and the C that corresponds to that is 0.015. The new table should contain:
> speed 8 and C 0.003
> speed 9 and C 0.004
> speed 7 and C 0.001How do you do this?
>
> Thanks,
> Jeffrey
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] mailing list
> https://stat.ethz.ch/mailman/listinfo/rhelp> PLEASE do read the posting guide http://www.Rproject.org/postingguide.html> and provide commented, minimal, selfcontained, reproducible code.
>
______________________________________________
[hidden email] mailing list
https://stat.ethz.ch/mailman/listinfo/rhelpPLEASE do read the posting guide http://www.Rproject.org/postingguide.htmland provide commented, minimal, selfcontained, reproducible code.


Great! Thank you!
With the data, I would like to make a scatter plot with speed on the xaxis and C differences on the yaxis, with a different color to represent different dates. There are over 50 different dates, so I want 50 different colors on a single plot. How can I make this plot?
If I wanted to make 50 separate plots for 50 different dates, how can I do that?
Jeffrey

> Date: Thu, 20 Oct 2011 17:39:42 0700
> Subject: Re: [R] Calculating differences
> From: [hidden email]
> To: [hidden email]
> CC: [hidden email]
>
> Hi:
>
> Here's one way with the plyr package. Using ds as the name of your
> data frame (thank you for the dput and clear description of what you
> wanted, BTW),
>
> library('plyr')
> ddply(ds, .(date), mutate, minspd = min(speed), Cmin =
> C[which.min(speed)], diff = C  Cmin)
> speed C house date hour id minspd Cmin diff
> 1 3 0.697 1 719 18 1000 3 0.697 0.000
> 2 9 0.011 1 1027 8 10000 4 0.015 0.004
> 3 4 0.015 1 1027 8 10001 4 0.015 0.000
> 4 8 0.012 1 1027 8 10002 4 0.015 0.003
> 5 7 0.018 1 1030 11 10003 6 0.019 0.001
> 6 6 0.019 1 1030 11 10004 6 0.019 0.000
>
> HTH,
> Dennis
>
> On Thu, Oct 20, 2011 at 2:56 PM, Jeffrey Joh < [hidden email]> wrote:
> >
> > I have a table that looks like this:
> >
> > structure(list(speed = c(3,9,4,8,7,6), C = c(0.697, 0.011, 0.015, 0.012, 0.018, 0.019), house = c(1,
> > 1, 1, 1, 1, 1), date = c(719, 1027, 1027, 1027, 1030, 1030),
> > hour = c(18, 8, 8, 8, 11, 11), id = c("1000", "10000",
> > "10001", "10002", "10003", "10004")), .Names = c("speed",
> > "C", "house", "date", "hour", "id"), class = "data.frame", row.names = c("1000",
> > "10000", "10001", "10002", "10003", "10004"))
> >
> > I want to determine the minimum speed for each date, and the C that corresponds to that lowest speed.Then I want to make a table that contains all speeds and the difference between C and the lowest C.
> >
> > For example, on the date 1027, the minimum speed is 4 and the C that corresponds to that is 0.015. The new table should contain:
> > speed 8 and C 0.003
> > speed 9 and C 0.004
> > speed 7 and C 0.001How do you do this?
> >
> > Thanks,
> > Jeffrey
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > [hidden email] mailing list
> > https://stat.ethz.ch/mailman/listinfo/rhelp> > PLEASE do read the posting guide http://www.Rproject.org/postingguide.html> > and provide commented, minimal, selfcontained, reproducible code.
> >
______________________________________________
[hidden email] mailing list
https://stat.ethz.ch/mailman/listinfo/rhelpPLEASE do read the posting guide http://www.Rproject.org/postingguide.htmland provide commented, minimal, selfcontained, reproducible code.

