# `IaGraph` Examples: Latitude-Longitude Contour Plots

## Settings and Data

All examples below use the following import statements, data, and system variable settings. We control the x- and y-axis tick labels via system variables because we wish to express latitude/longitude with N/S, E/W designations. Also, in our example data we set some values to "missing," and change `data` into a masked array (MA) to accomodate those missing values (missing value value is 1e+20):

```>>> import Numeric as N
>>> import IaGraph, MA
>>> from IaGraph import *
>>> lat = N.arange(13) * 15.0 - 90.0
>>> lon = N.arange(25) * 15.0 - 180.0
>>> data = N.outerproduct( N.sin(lat*N.pi/360.) \
...                      , N.cos(lon*N.pi/360.) )
>>> data[3:4,6:8] = 1e+20
>>> data = MA.masked_values(data, 1e+20)
>>> sysvar = IaGraph.Sysvar()
>>> sysvar.__class__.x_tickvalues = \
...     {-180:'180W', -90:'90W', 0:'0', 90:'90E', 180:'180E'}
>>> sysvar.__class__.y_tickvalues = \
...     {-90:'90S', -45:'45S', 0:'EQ', 45:'45N', 90:'90N'}
```

A link to the full source code for all the examples on this page is at the bottom of this page. For more information on the `contour` command, type `help(contour)`.

## Examples

### Default plot with continents

```>>> contour(data, lon, lat, continents=1)
```

### Remove color bar, add titles, show continents, and use blue-red color map

```>>> contour( data, lon, lat \
...    , ctindex=11 \
...    , colorbar=0 \
...    , title='Example Contour Plot' \
...    , xtitle='Longitude [deg]',ytitle='Latitude [deg]' \
...    , continents=1 )
```

## Full Code For Examples

Return to IaGraph Home Page.
Return to Johnny Lin's Python Library.

Updated: December 19, 2003 by Johnny Lin <email address>. License.