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from Numeric import *
from plplot import *
NS = 20
NX = 35
NY = 46
PERIMETERPTS = 100
XSPA = 2./(NX-1)
YSPA = 2./(NY-1)
tr = array((XSPA, 0.0, -1.0, 0.0, YSPA, -1.0))
def mypltr(x, y, data):
result0 = data[0] * x + data[1] * y + data[2]
result1 = data[3] * x + data[4] * y + data[5]
return array((result0, result1))
def main():
fill_width = 2
cont_color = 2
cont_width = 3
# Set up data array
x = (arrayrange(NX) - (NX/2)) / float(NX/2)
x.shape = (-1,1)
y = (arrayrange(NY) - (NY/2)) / float(NY/2) - 1.
zz = -sin(7.*x) * cos(7.*y) + x*x - y*y
ww = -cos(7.*x) * sin(7.*y) + 2.*x*y
zmin = min(zz.flat)
zmax = max(zz.flat)
clevel = zmin + (zmax - zmin) * (arrayrange(NS)+0.5)/NS
shedge = zmin + (zmax - zmin) * (arrayrange(NS+1))/NS
# Build the identity transformation between grid and world coordinates
# using mypltr.
# Note that *for the given* tr, mypltr(i,j,tr)[0] is only a function of i
# and mypltr(i,j,tr)[1] is only function of j.
xg0 = mypltr(arange(NX),0,tr)[0]
yg0 = mypltr(0,arange(NY),tr)[1]
# Build the 1-d coord arrays.
distort = .4
xx = xg0
xg1 = xx + distort * cos( .5 * pi * xx )
yy = yg0
yg1 = yy - distort * cos( .5 * pi * yy )
# Build the 2-d coord arrays.
xx.shape = (-1,1)
xg2 = xx + distort*cos((0.5*pi)*xx)*cos((0.5*pi)*yy)
yg2 = yy - distort*cos((0.5*pi)*xx)*cos((0.5*pi)*yy)
# Plot using identity transform
pladv(0)
plvpor(0.1, 0.9, 0.1, 0.9)
plwind(-1.0, 1.0, -1.0, 1.0)
plpsty(0)
# Note another alternative to produce the identical result in a different way
# is to use the command:
# plshades(zz, -1.0, 1.0, -1.0, 1.0, shedge, fill_width, 1)
# The above command works because xmin, xmax, ymin, and ymax do an effective
# linear transformation on the index ranges. (We could have dropped
# xmin, xmax, ymin, ymax since the defaults are -1.0, 1.0, -1.0, 1.0, but
# for pedagogical reasons we left them in.) The alternative below using
# mypltr does the exact same linear transformation because of the way that
# the tr array has been defined. Note that when pltr and pltr_data are
# defined, xmin, xmax, ymin, ymax are completely ignored so we can drop
# them from the argument list.
plshades(zz, shedge, fill_width, 1, mypltr, tr)
plcol0(1)
plbox( "bcnst", 0., 0, "bcnstv", 0., 0 )
plcol0(2)
pllab( "distance", "altitude", "Bogon density" )
# Plot using 1d coordinate transform
pladv(0)
plvpor(0.1, 0.9, 0.1, 0.9)
plwind(-1.0, 1.0, -1.0, 1.0)
plpsty(0)
plshades(zz, shedge, fill_width, 1, pltr1, xg1, yg1)
plcol0(1)
plbox( "bcnst", 0.0, 0, "bcnstv", 0.0, 0 )
plcol0(2)
pllab( "distance", "altitude", "Bogon density" )
# Plot using 2d coordinate transform
pladv(0)
plvpor(0.1, 0.9, 0.1, 0.9)
plwind(-1.0, 1.0, -1.0, 1.0)
plpsty(0)
plshades(zz, shedge, fill_width, 0, pltr2, xg2, yg2)
plcol0(1)
plbox( "bcnst", 0.0, 0, "bcnstv", 0.0, 0 )
plcol0(2)
plcont(ww, clevel, pltr2, xg2, yg2)
pllab( "distance", "altitude", "Bogon density, with streamlines" )
# Plot using 2d coordinate transform (with contours generated by plshades)
pladv(0)
plvpor(0.1, 0.9, 0.1, 0.9)
plwind(-1.0, 1.0, -1.0, 1.0)
plpsty(0)
# Note default cont_color and cont_width are zero so that no contours
# are done with other calls to plshades. But for this call we specify
# non-zero values so that contours are drawn.
plshades(zz, shedge, fill_width, cont_color, cont_width,\
0, pltr2, xg2, yg2)
plcol0(1)
plbox( "bcnst", 0.0, 0, "bcnstv", 0.0, 0 )
plcol0(2)
# plcont(ww, clevel, "pltr2", xg2, yg2, 0)
pllab( "distance", "altitude", "Bogon density" )
# Example with polar coordinates that demonstrates python wrap support.
pladv(0)
plvpor(0.1, 0.9, 0.1, 0.9)
plwind(-1.0, 1.0, -1.0, 1.0)
# Build new coordinate matrices.
r = arrayrange(NX)/(NX-1.)
r.shape = (-1,1)
t = (2.*pi/(NY-1.))*arrayrange(NY-1)
xg = r*cos(t)
yg = r*sin(t)
z = exp(-r*r)*cos(5.*pi*r)*cos(5.*t)
# Need a new shedge to go along with the new data set.
zmin = min(z.flat)
zmax = max(z.flat)
shedge = zmin + ((zmax - zmin)/NS) * (arrayrange(NS+1))
plpsty(0)
# Now we can shade the interior region. Use wrap=2 to simulate additional
# point at t = 2 pi.
plshades(z, shedge, fill_width, 0, pltr2, xg, yg, 2)
# Now we can draw the perimeter. (If do before, plshades may overlap.)
t = 2.*pi*arrayrange(PERIMETERPTS)/(PERIMETERPTS-1.)
px = cos(t)
py = sin(t)
plcol0(1)
plline( px, py )
# And label the plot.
plcol0(2)
pllab( "", "", "Tokamak Bogon Instability" )
# Restore defaults
plcol0(1)
main()
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