[R] averaging X of specific Y (latitude)

[David L Carlson]

It is not necessary to rearrange the order. The aggregate function will do
that. To get the mean Range for a latitude combining species within a
latitude just remove Species:

> aggregate(Range~floor(Latitude), dta, mean)
  floor(Latitude)   Range
1               9 616.440
2              10 714.360
3              12 851.550
4              16 690.770
5              18 766.155

-----------
David 


From: Elaine Kuo [mailto:elaine.kuo.tw at gmail.com] 
Sent: Sunday, December 16, 2012 5:17 PM
To: dcarlson at tamu.edu; r-help at r-project.org; r-sig-geo at stat.math.ethz.ch
Subject: Re: [R] averaging X of specific Y (latitude)

Thank you, David.

Your answer reminded me of rearranging the order according to the latitude 
before running the calculation.

One more question, 
please kindly help with the code to calculate the mean of the ranges of the
same latitude?
Or should any re-arrangement be noticed before the mean calculation?

Thank you.

Elaine



----- Original Message -----
From: David L Carlson <dcarlson at tamu.edu>
To: 'Elaine Kuo' <elaine.kuo.tw at gmail.com>; r-help at r-project.org;
'r-sig-geo' <r-sig-geo at stat.math.ethz.ch>
Cc:
Sent: Sunday, December 16, 2012 11:32 AM
Subject: Re: [R] averaging X of specific Y (latitude)

It is better to use dput() in R to create a text version of your data for us
to work with. The aggregate command below gives you the mean ranges by
butterfly species and latititude and saves the result as Bfly. The
colnames() command simply renames the columns:

> dta <- structure(list(Species = structure(1:11, .Label = c("Butterfly A1",

+ "Butterfly A2", "Butterfly A3", "Butterfly A4", "Butterfly B1",
+ "Butterfly B2", "Butterfly B3", "Butterfly B4", "Butterfly B5",
+ "Butterfly C1", "Butterfly C2"), class = "factor"), Range = c(130.5,
+ 450.68, 1102.38, 893.34, 820.2, 872.2, 488.2, 620.11, 982.78,
+ 720.32, 912.2), Latitude = c(9.45, 10.2, 9.3, 16.4, 10.54, 10.87,
+ 16.79, 18.3, 12.98, 12.67, 18.07)), .Names = c("Species", "Range",
+ "Latitude"), class = "data.frame", row.names = c(NA, -11L))
> Bfly <- aggregate(Range~Species+floor(Latitude), dta, mean)
> colnames(Bfly) <- c("Species", "Latitude", "Mean")
> Bfly
        Species Latitude    Mean
1  Butterfly A1        9  130.50
2  Butterfly A3        9 1102.38
3  Butterfly A2       10  450.68
4  Butterfly B1       10  820.20
5  Butterfly B2       10  872.20
6  Butterfly B5       12  982.78
7  Butterfly C1       12  720.32
8  Butterfly A4       16  893.34
9  Butterfly B3       16  488.20
10 Butterfly B4       18  620.11
11 Butterfly C2       18  912.20

----------------------------------------------
David L Carlson
Associate Professor of Anthropology
Texas A&M University
College Station, TX 77843-4352

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Elaine Kuo
> Sent: Saturday, December 15, 2012 10:15 PM
> To: r-help at r-project.org; r-sig-geo
> Subject: [R] averaging X of specific Y (latitude)
>
> Hello
>
>
>
> I have a table describing butterfly range traits.
>
> It is composed of three columns as below
>
>
>
> Species name  range size (X)    latitude of range midpoint (Y)
>
>
>
> There are 11 kinds of butterflies.
>
> Each has its range size, and the latitude of each range midpoint ranges
> from 9 to 19.
>
> I would like to have the average range size of every degree of
> latitude.
>
> For example, the average range size of latitude degree 10 (10.0-10.99:
> Butterfly A2, B1, B2)
>
> Please kindly help with R code to calculate the average values.
>
> Thank you.
>
>
> Elaine
>
>
> The details are as followed.
>
>
>
> Butterfly A1      130.5                 9.45
>
> Butterfly A2      450.68                           10.2
>
> Butterfly A3      1102.38                        9.3
>
> Butterfly A4            893.34                             16.4
>
> Butterfly B1           820.2                               10.54
>
> Butterfly B2            872.2                               10.87
>
> Butterfly B3            488.2                               16.79
>
> Butterfly B4            620.11                             18.3
>
> Butterfly B5            982.78                             12.98
>
> Butterfly C1           720.32                             12.67
>
> Butterfly C2            912.2                               18.07
>
>     [[alternative HTML version deleted]]
>
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