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2.2.4 Preferences

The preferences menu is shown in the figure.

Time

 

The date can be displayed as Year/Month/Day triples, or as the year and the ordinal number of the day for that year. This is a toggle switch.

Messages

 

Messages to the user can be directed either to pop-up windows ("Messages to Pop-up Window") or to the Matlab command-line interface ("Messages to Workspace"). This is a toggle switch, click it to change its value.

Get Data Threshold

 

This button calls up a dialog box that controls the data request threshold. (See the figure.)

This threshold marks the maximum size of data file that the Matlab DODS browser will fetch without prompting the user for confirmation. For example, if the threshold is set at 1 megabyte of data, the user will be prompted for confirmation of any data request likely to return more than 1 megabyte of data. Because the OPeNDAP Matlab GUI cannot know exactly how big a dataset is until it has actually downloaded the entire data request, this threshold works with estimates.

 

The Data Threshold Dialog. Use this dialog to control the estimated size of the data request.

NOTE: A further problem with this threshold is that the estimates are about how much memory the data will occupy in Matlab memory, not the size of the the transmitted information. The memory occupied by data in Matlab can be much larger than the amount of data transmitted. Any number in Matlab occupies eight bytes of storage space. Many DODS data--especially satellite data--are transmitted as single byte numbers. Further, the OPeNDAP Matlab GUI has no way to know whether the transmitted data were compressed or not. This can increase the size of this discrepancy. In other words, this threshold is meant to be a guide to an informed user, not a precise prediction.

Fontsize

 

This button pops up a submenu you can use to select the size of the font used to display titles, legends, and so on.

Color

 

This button pops up a submenu you can use to select the colors of various browser features. See the figure.

 

Color Menu

Save

 

Save the preferences to the file from which they were loaded. See here.

Load Palette

 

Opens a dialog allowing you to load a palette for mapping. See the figure.

 

Color Palette Dialog

The colormap is an ASCII file containing a standard Matlab RGB colormap. This is a 3-column matrix with values between 0 and 1. The columns represent the relative strength of the red, green, and blue components, respectively. Matlab also has a number of built-in colormaps (type help colormap at the Matlab prompt for more information). These can be specified from the Matlab command line.

The avhrrpal.pal file (the default color palette) consists of 255 lines like this:

...
0.2000 0.0000 0.3000
0.3700 0.0000 0.5000
0.4516 0.0000 0.7000
0.4548 0.0323 0.8710
0.4548 0.2323 1.0000
...

The file represents a 255x3 array. You can think of it as a list of 255 colors, each of which is specified as a combination of red, green, and blue values (from left to right). Each value represents the fraction of intensity, with 1.0 equal to full intensity of that color component.

To use one of the colormaps that come with Matlab, you can create a palette in an external file with the following steps:

1. Create a color map with the following command:

   >> newpalette = hsv(256);
   

   Any of the following could substitute for the hsv in the above example. They are all colormaps supplied with Matlab:

   hsv

   Hue-saturation-value color map.

   hot

   Black-red-yellow-white color map.

   gray

   Linear gray-scale color map.

   bone

   Gray-scale with tinge of blue color map.

   copper

   Linear copper-tone color map.

   pink

   Pastel shades of pink color map.

   white

   All white color map.

   flag

   Alternating red, white, blue, and black color map.

   lines

   Color map with the line colors.

   colorcube

   Enhanced color-cube color map.

   jet

   Variant of HSV.

   prism

   Prism color map.

   cool

   Shades of cyan and magenta color map.

   autumn

   Shades of red and yellow color map.

   spring

   Shades of magenta and yellow color map.

   winter

   Shades of blue and green color map.

   summer

   Shades of green and yellow color map.

2. Save the result into an ASCII file:

   >> fid = fopen('newpalette.pal');
   >> fprintf(fid,'%g %g %g\n',newpalette');
   >> fclose(fid);
   

Set GUI Server

 

You can use the dialog summoned by this button (see the figure) to update your master list of datasets from some other source than the DODS central archive.

Save As

 

If you have changed preferences such as color, font, threshold or anything else, you can save these values by selecting this option. When the OPeNDAP Matlab GUI is next started, these same values will be read from the startup file, by default called browsopt.m. You can control the name with the Save As dialog box. To reload a preference file, use the Preferences,Load Prefs File button. Browser preference files are simple Matlab scripts and may be edited by hand.

The browser options saved with this command are described in Section 2.3.

Load Prefs File

 

This button allows you to load a set of user preferences saved from a previous browser session. Clicking the button brings up the dialog.. The browser will execute the given preferences file, expecting it to be a file such as are saved by the Save Preferences command. Note that the preferences file must be somewhere on your Matlab path. If you are unsure, type path at the Matlab prompt and examine the result.

The browser preferences loaded with this command are described in Section 2.3. Saves the current preferences in a file of your choosing.

Use Defaults

 

Selecting this option will restore to their default values:

• The size and screen position of the browse windows
• The resolution factors (multiples of the dataset stride available through the Resolution menu)
• The font size
• The color scheme for the user display
• The time format (this is year/month/day)
• The axis limits
• The data size threshold (1Mb)
• The color limits (0 255)
• The color palette.
• The limits of the four browser axes (time, depth, latitude, longitude).

Clicking this button also clears the ranges, dataset and variable selections. See Section 2.3 for more information about the options.