##
POLAR_CONTOUR

The
POLAR_CONTOUR procedure
draws a contour plot from data in polar coordinates. Data can be regularly- or irregularly-gridded. All of the keyword options supported by CONTOUR are available to POLAR_CONTOUR.

This routine is written in the IDL language. Its source code can be found in the file ```
polar_contour.pro
```

in the ```
lib
```

subdirectory of the IDL distribution.

###
Calling Sequence

POLAR_CONTOUR, *
Z, Theta, R*

###
Arguments

####
Z

The data values to be contoured. If the data is regularly gridded, *
Z*
must have the dimensions (N_ELEMENTS(*
Theta*
), N_ELEMENTS(*
R*
). Note that the ordering of the elements in the array *
Z*
is opposite that used by the POLAR_SURFACE routine.

####
Theta

A vector of angles in radians. For regularly-gridded data, *
Theta*
must have the same number of elements as the first dimension of *
Z*
. For a scattered grid, *
Theta*
must have the same number of elements as *
Z*
.

####
R

A vector of radius values. For regularly-gridded data, *
R*
must have the same number of elements as the second dimension of *
Z*
. For a scattered grid, *
R*
must have the same number of elements as *
Z*
.

###
Keywords

POLAR_CONTOUR accepts all of the keywords accepted by the CONTOUR routine except C_LABELS, DOWNHILL, FOLLOW, PATH_FILENAME, PATH_INFO, and PATH_XY. See
CONTOUR
. In addition, there is one unique keyword:

####
SHOW_TRIANGULATION

Set this keyword to a color index to be used in overplotting the triangulation between datapoints.

###
Example

The first example uses POLAR_CONTOUR with regularly-gridded data:

nr = 12

nt = 18

r = FINDGEN(nr)/(nr-1)

theta = 2*!PI * FINDGEN(nt)/(nt-1) C

z = COS(theta*3) # (r-0.5)^2

POLAR_CONTOUR, z, theta, r, /FILL, c_color=[2, 3, 4, 5]