## 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 ; The number of radii.

nt = 18 ; The number of Thetas.

r = FINDGEN(nr)/(nr-1) ; Create a vector of radii.

theta = 2*!PI * FINDGEN(nt)/(nt-1) C; reate a vector of Thetas.

z = COS(theta*3) # (r-0.5)^2 ; Create some data values to be contoured.

POLAR_CONTOUR, z, theta, r, /FILL, c_color=[2, 3, 4, 5]
; Create the polar contour plot.