Working with graphical output

You have seen already how to visualise outputs

Output formats

All graphical output formats are generated through Magics. Detailed descriptions of the output formats and their settings can be found in the Magics reference documentation.

The table below gives

Exporting from the plot window

Whenever you have a plot window open you are able to export the plot into other file formats. You can either select the export button in the menu (looks like a disk)

  , by selecting File > Export  or by using the Ctrl+s keyboard shortcut.

You will get a dialogue as shown below

Exercises

1. Try to save your plot as a PDF.
2. Try to save your plot as a SVG without and with fixed dimensions.
   
   1. Open both files in Firefox and see how the plots behave when you resize the browser window.
   2. Open one of the SVGs in inkscape and edit the images (for example add some text) and save it as a PDF.

Setting output formats in macro code

output_common = ( 
      output_name            : "/tmp/myOutputTest",
      output_width           : 1000,
      output_title           : "Map of Z500",
      output_debug           : "ON",
      output_filelist        : "ON",
      output_filelist_name   : "/tmp/filelist.txt"
)

ps = ps_output(
      output_common,
      output_ps_scale        : 0.9,
      output_ps_colour_model : "CMYK"
)

png = png_output(
      output_common,
      output_cairo_transparent_background : "ON"
)

svg = svg_output(
      output_common,
      output_svg_fix_size : "ON",
      output_svg_meta     : "Metview map of Z500",
      output_svg_desc     : "This file was generated for the Training course"
)

kml = kml_output(
      output_common,
      kml_description : "This file was generated for the Training course",
      kml_author      : "Stephan Siemen",
      kml_link        : "http://www.ecmwf.int",
      kml_latitude    : 30,
      kml_longitude   : 120,
      kml_coastlines  : "ON"
)

output_drivers = [ps, png, svg, kml]

setoutput(output_drivers)

data = read("z500.grib")

plot(data)

Setting output dependent on runmode

The way to code run mode dependent outcomes is by using the function runmode(). It returns a string with the run mode:

mode = runmode()

So it is enough to check this string and to code accordingly, either using if/else conditions or the case/of condition test. To introduce the new functionality replace the existing unconditional call to

setoutput() by the following lines of code :

# check run mode
mode = runmode()

# select outcome dependent on run-mode
if(mode = "execute")
 then setoutput(to_pngfile)
else if (mode = "batch")
 then setoutput(to_psfile)
else if (mode = "visualise") 
 then print('Plotting to screen')
else if (mode = "prepare")
 then print('Plotting to screen')
else
 fail("Only execute, batch and visualise allowed")
end if

Now, depending on how you call the macro your output will be directed to different media. Choose different options from the icon’s right-click menu to see what happens. Note that you can also simulate these actions from within the Macro editor ( Program | Run Options). The ‘prepare’ run mode is the default one when you run your macro from the Macro editor. The ‘batch’ run mode will be explained in a later paragraph.

If you select an option not covered by the allowed run modes (e.g. Save or Examine), the macro will stop, turn red (failed run) and issue an error message - this behaviour is provided by the fail() function. A related function, stop(), will do the same but allow the macro to exit in the green state (successful run). Note that you may have to see that it has worked! To delete the output files before running the macro in order to

To run the macro in batch mode, you call Metview with the option -b followed by the macro name on the command line (assuming you are running from the same directory as the macro - otherwise you must provide a path to it). For example:

metview -b step8

The newlines within the conditional branching part of the code are down to personal preference. You could also have formatted the code as follows:

if (mode = "execute") then

setoutput(to_pngfile)

else if (mode = "batch") then

setoutput(to_psfile)

If You Have Extra Time ...

One important piece of functionality that we have omitted is the ability to save our derived data. Add some code to handle the Save run mode by saving the derived data in a file. There are three things you will have to do:

• at the end of the run mode checks, instead of

else fail ( ... )

• we should not fail if the mode is “save”:

else if (mode <> "save")

 then fail ( ... )

• we must again check the run mode, and if it is Save then write the data to a file; otherwise plot the data.

KML as output format

KML is a very special output format. It contains the    it has no notion of output size.

Converting Geopoints to KML

Metview allows

Importing graphical layers through OGC Web Map Services (WMS)

Metview provides a WMS (Web Map Service) module which can be used to query an OGC-compliant WMS server, retrieve maps from it and overlay them with other data. The following material describes the use of WMS within Metview.

• WMS Tutorial : mv_wms_tutorial.pdf
• Files required for the WMS tutorial: wms_tutorial.tar