Maps.py - Map Background Configuration

Organization

Overview

The edit area generation software uses the maps database tables as input. These tables are populated by importing shape files provided by the National Weather Service. These tables are filtered by domain (based on the site) and attributes. There are different attributes available for each table. Refer to the AWIPS Map Background Database provided by the National Weather Service for details on the available shapefiles and the attributes contained within each shapefile. This information will be needed in order to tailor edit area generation for your site.

The user can select which polygons will be converted into edit areas and to which edit area groups they will be assigned.

This information is provided for you to help you understand the format of Maps.py. You should NEVER change the original Maps.py since your changes will be overwritten with the next upgrade. See the server configuration overview for information on how to make changes that are supported to the map backgrounds.

To override definitions in Maps.py, use the localMaps.py technique.

To update the maps database, refer to the MapFiles documentation, specifically the section on Updating Shapefiles.

Software releases after Jan 1, 2006 separate the map shapefile from the CORE GFE.   In some applications, such as AWIPS, the map shapefile configuration becomes the responsibility of the site since the map shapefiles will no longer be shipped with the GFE software. A separate install is available for non-AWIPS purposes and is posted with the software releases. If the associated Map Shapefile is not installed at your site, then sites will be responsible for:

• Downloading updated shapefiles from the NOAA1 web server
• Importing the downloaded shapefiles into the maps database
• Creating/modifying the localMaps.py file to reference the appropriate database tables

Maps.py Format

Site Information

CWA = siteConfig.GFESUITE_SITEID

Map Definitions

Basic Map with Automatically Generated Edit Areas

CWAzones = ShapeTable('zone')
CWAzones.name = CWA + '_zones'
CWAzones.editAreaName = ['state','zone']

Single String Format

CWAzones = ShapeTable('zone')
CWAzones.name = CWA + '_zones'
CWAzones.editAreaName = 'zone'

Examples of the names of the edit areas generated from the above snippet is shown in the following table:
 

zone value from shapefile	state (not used in this example)	Name of Edit Area
034	CO	zone034
041	CO	zone041
041	NE	zone041

Note that if a site's domain covers more than one state, this simple form of generating edit area names will not work. The "NE" example above illustrates that the same edit area name was generated even though the zones were from different states. Also note that the naming of the edit area includes the name "zone" only because the value of the zone value begins with a number.

NOTE: Changing the default set of edit area names as supplied in the baseline may render your text formatters and VTEC inoperable. The text formatters and VTEC assume standard UGC-named edit areas, such as COZ023 and UTC013.

List of Strings Format

A second, more complex form of the editAreaName involves using a Python list. The naming of an edit area is determined by using more than one attribute. This example uses the more complex form for the editAreaName, in which two attributes are specified.

CWAzones = ShapeTable('zone')
CWAzones.name = CWA + '_zones'
CWAzones.editAreaName = ['state','zone']

Examples of the names of the edit areas generated from the above snippet is shown in the following table:
 

zone value from shapefile	state (not used in this example)	Name of Edit Area
034	CO	CO_034
041	CO	CO_041
041	NE	NE_041

The edit area name is determined from the value of the state attribute, followed by an underscore character, and then the value of the zone attribute.

Here is the software algorithm for naming of edit areas:

• the value for each of the attributes is extracted from the shapefiles. All spaces and non-alphanumeric characters are removed from the value.
  Example: "Washington Meadows" would be changed to "WashingtonMeadows"
• if any of the values results in an empty string, then the edit area is not generated.
• the values are put together with an underscore separator for each of the attributes.
  Example: Attribute state has a value of "CO", Attribute zone has a value of "034". Result is CO_034.
• if the leading character of the result begins with a number, then the name of the first attribute is prefixed to the string.
  Example: If the preceding string was 034 and its attribute was zone, then the resulting edit area name becomes zone034.

Note that specification of an attribute that doesn't exist will simply use the name in the string. For example, if you are creating edit areas and you want them of the form ISC_xxx, where xxx is the value of the wfo attribute. The editAreaName string would be the following:

ISCareas.editAreaName = ['ISC', 'wfo'] 

NOTE: Changing the default set of edit area names as supplied in the baseline may render your text formatters and VTEC inoperable. The text formatters and VTEC assume standard UGC-named edit areas, such as COZ023 and UTC013.

Function Format

Occasionally there is a need to calculate a special edit area name and the single or list of strings methods are not sufficient. The function format requires the user to name a function and then define a function. The function has one argument, which receives a dictionary of attribute names and their values. The return value of the function is a string which becomes the edit area name.

For example, lets say that we want edit area names based on the county FIPS code. The desired format is stateCfips, such as COC013, for Colorado County #13. The county shapefile has a 'STATE' attribute, such as "CO", and it has a 'FIPS' attribute, such as 08013 for Colorado County #13.   Using the list of strings format, ['STATE', 'C', 'FIPS'], you would end up with CO_C_08013, when we really want COC013.

def cwaEAN(atts):
    fips = atts['fips'][-3:]        #take the last three characters from the FIPS code
    s = atts['state'] + "C" + fips  #assemble the name
    return s                        #return the complete edit area name
    
CWAcounties = ShapeTable('county')
CWAcounties.name = CWA + '_counties'
CWAcounties.editAreaName = cwaEAN

{'countyname': 'Delta', 
 'cwa': 'MQT'
 'fe_area': 'sr', 
 'fips': '26041', 
 'lat': 45.82085, 
 'lon': -86.909679999999994, 
 'state': 'MI', 
 'time_zone': 'E',
}

Basic Map with Automatically Generated Edit Areas with group definition

CWAzones = ShapeTable('zone')
CWAzones.name = CWA + '_zones'
CWAzones.editAreaName = 'zone'
CWAzones.groupName = 'Zones'

Filtered Map with Automatically Generated Edit Areas

pythonMapName.filter(lambda x : x['ATTRIBUTENAME'] = AttributeValue)

where ATTRIBUTENAME is one of the attributes in the shapefile, and AttributeValue is the value that must match in the shapefile for this shape to be kept in the map. Attributes for the NWS shapefiles can be obtained from the AWIPS Map Catalog AWIPS Map Background Database.

CWAzones = ShapeTable('Zone')
CWAzones.name = CWA + '_zones'
CWAzones.filter(lambda x : x['cwa'] == CWA)
CWAzones.editAreaName = cwazones

The "lambda" function is a shortcut method of writing a function, the code snippet below performs the identical function:

def cwaZoneFilt(x):
    return x['cwa'] == CWA

CWAzones = ShapeTable('zone')
CWAzones.name = CWA + '_zones'
CWAzones.filter(cwaZoneFilt)
CWAzones.editAreaName = cwazones

Since this is all Python code, there is another technique you can use to write a filter function which is complex. Here is an example of writing a filter that selects certain counties (Summit, Sandusky, Huron, and Medina) from the county database table for a particular state (Ohio) and cwa (Cleveland):

def exampleFilt(x):
    myCounties = ['Summit', 'Sandusky', 'Huron', 'Medina']
    return x['countyname'] in myCounties and x['st'] == "OH" and x['cwa'] = 'CLE'

OHcounties = ShapeTable('county')
OHcounties.name = 'ExampleOHCounties'
OHcounties.filter(exampleFilt)
OHcounties.editAreaName = 'countyname'

Filtered Map with Automatically Generated Edit Areas with group definition

CWAzones = ShapeTable('zone')
CWAzones.name = CWA + '_zones'
CWAzones.filter(lambda x : x['cwa'] == CWA)
CWAzones.editAreaName = ['state','zone']
CWAzones.groupName = 'Zones'

Putting it all Together with the map list

maps = [ CWAcounties, Counties, CWAzones ]

Importing localMaps

# import the local maps file
try:
    import localMaps
except:
    pass