geocontour: Plots contour lines.

Description

The function plots contour lines. It is based on the Splus function "contour" with some changes and extensions. The main change is that coordinates are in lat, lon instead of x, y. There are two additions : 1. Possibility to have many colors. 2. Possibility to only plot lines within certain borders. 3. Possibility to have labels in a box on the plot. Note: to plot contour plots with fill between lines you use geocontour.fill

Usage

geocontour(grd, z, nlevels = 10, levels = NULL, labcex = 1, triangles = TRUE, reg = 0, fill = 1, colors = TRUE, col = 1, only.positive = FALSE, maxcol = 155, cex = 0.7, save = FALSE, plotit = TRUE, label.location = 0, lwd = 1, lty = 1, labels.only = FALSE, digits = 1, paint = FALSE, set = NA, col.names = c("lon", "lat"), csi = NULL, drawlabels = FALSE)

Arguments

grd

List with components lat and lon (or x,y) defining the grid values. Can be made for example by lat <- list(lat = seq(60,65,length = 100), lon = seq(-30,- 10,length = 200)). Also lat can be the output of the program grid and then the components lat$grpt$lat, lat$grpt$lon and lat$reg are used. See geocontour.fill.

Matrix or vector of values. Length nlat*nlon except when lat is a list with components lat$grpt and lat$xgr. Then the length of z is the same as the length of lat$xgr$lat and lat$xgr$lon.

nlevels

Number of contourlines. Used if the program has to determine the contourlines. Default value is 10. nlevels = 10 does not always mean 10 due to characteristic of the pretty command

levels

Ratio of textsize to current size. 1 means same size, 0.5 half size , 0 no text etc. Default value 1.

labcex

Character expansion of letters indicating the z value on the contour lines. Maybe used instead of a legend.

triangles

If TRUE the program makes 4 triangles from each element in the grid. In fact it makes the number of grid points approximately twice as many as before which means smoother contourlines. Default value TRUE. Triangles = TRUE is nessecary if the area was plotted with geocontour.fill. It fits with geocontour.fill.

reg

List with two components, reg$lat and reg$lon. Region of interest. Contourlines are only plotted inside the region. Holes in the region of interest begin with NA. If the region consists only of holes then reg$lat and reg$lon begin with NA.

fill

If fill is one the matrix is filled with zeros. If two it is filled with mean(z). Default is fill = 1. ( not an important parameter)

colors

If colors is TRUE the contour lines are plotted in many colors. Else only in one. The lines can also be in one color using many linetypes.

col

Number of color (colors) used to plot contourlines. Default value is 1 if colors is FALSE. If colors is TRUE the default value is found from the number of contour lines.

only.positive

Logical value. If FALSE then negative values are allowed else negative values are set to zero. Default value is FALSE.

maxcol

Maximum color number in the Splus graphics, default value 155.

cex

Character expansion of digits, default value is 0.7.

save

If true the contour lines are saved in a list so they can later be plotted with geolines. Default value is false.

plotit

If TRUE the lines are plotted on the graphics device else not. Default value is true.

label.location

List with components lat and lon (or x,y) Gives the lower left and upper right corner of the box where the labels are put. Default value is 0 that means no labels are put on the drawing (except when geopar$cont = TRUE). l1 is best given by geolocator or directly by specifying label.location = "locator".

lwd

Line with. Default value is the value set when the program was called.

lty

ine type. If lty is a vector of the same length of levels it specifies the linetype for each contour line. Default value is the same as when the program was called.

labels.only

If true only the labels are drawn. Default is false.

digits

Number of digits in labels. Default value is one.

paint

if true borders of regions will be painted.

set

Set something.

col.names

the names of the vectors containing the data in grd. Default is col.names = c("lon","lat").

csi

Size of character. This parameter can not be set in R but for compatibility with old Splus scripts the parameter cex is readjusted by cex = cex*csi/0.12. Use of this parameter is not recommended. Default value is NULL i.e not used.

drawlabels

Draw labels on the contour lines? Default FALSE.

Value

No values returned.

Side Effects

No side effects.

Examples

Run this code

###################################################
     # Example l                                       #
     ###################################################
## Not run: 
#      geoplot(deg, cont = TRUE)                        # Plot initialized.
#      geocontour(grd$lat,grd$lon,z,nlevels = 10,
#                 neg = FALSE,reg = reg,colors = TRUE)          # Contour plot.
#      geoplot(deg,pch = " ",cont = TRUE,new = TRUE)           # Plot over contourplot.
# ## End(Not run)
     ###################################################
     # Example 2 Sea Tempeture.                        #
     ###################################################

     # The following data names used are in Icelandic, stodvar means
     # stations and botnhiti means temperature.

     geoplot()
     gbplot(500)
     grd <- list(lat = seq(63,67,length = 30),
                 lon = seq(-28,-10,length = 50))
     labloc <- list(lat = c(63.95,65.4),lon = c(-19.8,-17.3))

     grd1 <- geoexpand(grd)                       # Make grid.
     grd2 <- geoinside(grd1,gbdypif.500)
     grd2 <- geoinside(grd2,island,robust = FALSE,option = 2)
     # Use only the points where depth < 500 and outside Iceland.
## Not run: 
#      #xx <- loess(botnhiti~ lat*lon,degree = 2,spaALSEn = 0.25,
#      #            data = stodvar, na.action = na.omit)
#      # Use loess for interpolating.
# 
#      #grd2$temp <- predict(xx,grd2)
#      #geocontour(grd2,z = grd2$temp,levels = c(0,1,2,3,4,5,6,7),
#      #           label.location = labloc)
# 
#      ######################################################
#      # Example 3 example of gam() and indexes.            #
#      ######################################################
# 
#      stations<-data.frame(lat = stodvar$lat,lon = stodvar$lon,
#                           temp = stodvar$botnhiti)
#      # Making a partial data.frame from a big one called stodvar,
#      # which means stations in Icelandic.
# 
#      stations[1:5,]             # Show first 5 lines all columns
#                                 # in stations.
#      dim(stations)              # Length of (lines,colums).
#      dim(stations[!is.na(stations$temp),])      # Without NAs.
#      my.data <- stations[!is.na(stations$temp),]
#      my.data <- my.data[!is.na(my.data$lat),]
#      my.data <- my.data[!is.na(my.data$lon),]
#      # my.data is now same as stations but witout NAs in lat,
#      # lon and temp.
# 
#      pred.grid <- list(lat = seq(63.25,67.25,length = round((67.25-63.25+1)*8)),
#                        lon = seq(-27,-11.5,length = round((27-11.5+1)*4)))
#      pred.grid <- geoexpand(pred.grid)
#      # Making a grid to fit our area of interest.
#      pred.grid <- geoinside(pred.grid,gbdypif.500)
#      # Points within 500m.
#      pred.grid <- geoinside(pred.grid,island,robust = FALSE,option = 2)
#      # Points outside  of Iceland.
# 
#      geoplot(grid = FALSE)
#      my.data <- geoinside(my.data,island,robust = FALSE,option = 2)
#      geopoints(my.data,pch = ".")
# 
#      fit <- gam(temp~lo(lat,lon,span = 0.1),data = my.data)
#      # see help(gam)
#      # can also do:
#      # fit <- loess(temp~lon*lat,data = my.data,span = 0.1)
#      # fit <- gam(temp~ns(lon,df = 7)*ns(lat,df = 5),data = my.data)
# 
#      pred.grid$pred.temp <- predict(fit,newdata = pred.grid)
#      geocontour(pred.grid,z = pred.grid$pred.temp,levels = 0:7,
#                 label.location = labloc)
# ## End(Not run)

Run the code above in your browser using DataLab