Plot contours of a state-variable of the analytic element model

contours() creates a contour plot of a state-variable computed by the analytic element model aem, or adds the contour lines to an existing plot.

Usage

contours(
  aem,
  x,
  y,
  variable = c("heads", "streamfunction", "potential"),
  asp = 1,
  ...
)

Arguments

aem: aem object.
x: numeric, vector or marginal x coordinates at which the gridded values are computed. These must be in ascending order.
y: numeric, vector or marginal y coordinates at which the gridded values are computed. These must be in ascending order.
variable: character indicating which state-variable to plot. Possible values are heads (default), streamfunction and potential.
asp: the y/x aspect ratio, see plot.window(). Defaults to 1 (equal unit lengths).
...: additional arguments passed to contour().

Value

A contour plot of the selected variable.

Details

contours() is a wrapper around contour(). It obtains the values of variable at the grid points defined by marginal vectors x and y and constructs the matrix supplied to contour() by reversing the rows and transposing the matrix (see also the documentation of image()).

Examples

w <- well(xw = 50, yw = 0, Q = 200)
wi <- well(xw = -200, yw = 0, Q = -100)
uf <- uniformflow(gradient = 0.002, angle = -45, TR = 100)
rf <- constant(-1000, 0, hc = 10)
ml <- aem(k = 10, top = 10, base = 0, n = 0.2, w, wi, uf, rf)

# grid points
xg <- seq(-350, 200, length = 100)
yg <- seq(-125, 125, length = 100)

contours(ml, xg, yg, nlevels = 20, col = 'dodgerblue', labcex = 1)
contours(ml, xg, yg, 'streamfunction', nlevels = 20, col = 'orange',
         drawlabels = FALSE, add = TRUE)


# Not to be confused by contour()
try(
contour(ml, xg, yg, nlevels = 20, col = 'dodgerblue', labcex = 1)
)
#> Error in contour.default(ml, xg, yg, nlevels = 20, col = "dodgerblue",  : 
#>   no proper 'z' matrix specified

# For image() or filled.contour()
library(graphics)
h <- heads(ml, xg, yg, as.grid = TRUE)
h_im <- t(h[dim(h)[1]:1,])
image(xg, yg, h_im, asp = 1)
contour(xg, yg, h_im, asp = 1, add = TRUE) # contours() is a wrapper for this

filled.contour(xg, yg, h_im, asp = 1)