R: Water Acidity in Lakes

LakeAcidity {gss} | R Documentation

## Water Acidity in Lakes

### Description

Data extracted from the Eastern Lake Survey of 1984 conducted by the United States Environmental Protection Agency, concerning 112 lakes in the Blue Ridge.

### Usage

    data(LakeAcidity)

### Format

A data frame containing 112 observations on the following variables.

`ph` | Surface ph.
`cal` | Calcium concentration.
`lat` | Latitude.
`lon` | Longitude.
`geog` | Geographic location, derived from `lat` and `lon`

### Details

`geog` was generated from `lat` and `lon` using the code given in the Example section.

### Source

Douglas, A. and Delampady, M. (1990), Eastern Lake Survey – Phase I: Documentation for the Data Base and the Derived Data sets. Tech Report 160 (SIMS), Dept. Statistics, University of British Columbia.

### References

Gu, C. and Wahba, G. (1993), Semiparametric analysis of variance with tensor product thin plate splines. Journal of the Royal Statistical Society Ser. B, 55, 353–368.

### Examples

    ## Converting latitude and longitude to x-y coordinates
    ## Not run: ltln2xy <- function(latlon,latlon0) {
      lat <- latlon[,1]*pi/180; lon <- latlon[,2]*pi/180
      lt0 <- latlon0[1]*pi/180; ln0 <- latlon0[2]*pi/180
      x <- cos(lt0)*sin(lon-ln0); y <- sin(lat-lt0)
      cbind(x,y)
    }
    data(LakeAcidity)
    latlon <- as.matrix(LakeAcidity[,c("lat","lon")])
    m.lat <- (min(latlon[,1])+max(latlon[,1]))/2
    m.lon <- (min(latlon[,2])+max(latlon[,2]))/2
    ltln2xy(latlon,c(m.lat,m.lon))
    ## Clean up
    rm(ltln2xy,LakeAcidity,latlon,m.lat,m.lon)
    ## End(Not run)

[Package gss version 2.1-7 Index]