Create an Object - Grids
listGridFieldsInFile - Lists the fields in a file brought in with loadGrid. The output is shortname ; longname
Usage: myData = listGridFieldsInFile(keywords)
Keywords - required:
| filename= |
directory path to local gridded file |
Example:
listGridFieldsInFile(filename='C:/Users/myUser/gfs.grb')
listGridLevelsInField - Lists the vertical levels included in a field of a loadGrid file
Usage: myData = listGridLevelsInField(keywords)
Keywords - required:
| filename= |
directory path to local gridded file |
| field= |
the short name of the field to list levels of. A listing of field short names included in a file can be printed using listGridFieldsInFile |
Example:
listGridLevelsInField(filename='C:/Users/myUser/gfs.grb',field='Temperature_Isobaric')
listGridTimesInField - Lists the times included in a field of a loadGrid file
Usage: myData = listGridTimesInField(keywords)
Keywords - required:
| filename= |
directory path to local gridded file |
| field= |
the short name of the field to list times of. A listing of field short names included in a file can be printed using listGridFieldsInFile |
Example:
listGridTimesInField(filename='C:/Users/myUser/gfs.grb',field='Temperature_Isobaric')
loadGrid - Loads local netCDF, hdf, and grib files.
Usage: myData = loadGrid(keywords)
Keywords - required:
| filename= |
directory path to local gridded file |
| field= |
the short name of the field to load. A listing of field short names included in a file can be printed using listGridFieldsInFile. |
Keywords - optional:
| level= |
the vertical level and units to load. Default="All". A listing of vertical levels included with a field can be printed using listGridLevelsInField. Example: level="1000 hPa" |
| time= |
the time to load. This can be an integer representing the index of time to be loaded (Default=0 for earliest time). A listing of times included with a field can be printed using listGridTimesInField. This can also be set as a date/time text string. Example: time="2014-01-16 18:00:00 UTC" |
| xStride= |
integer value to reduce the resolution of display in the x-direction. Default=1 for full resolution. Higher values reduce the resolution. |
| yStride= |
integer value to reduce the resolution of display in the y-direction. Default=1 for full resolution. Higher values reduce the resolution. |
| stride= |
integer value to reduce the resolution of the display in the x and y-directions. Default=1 for full resolution. Higher values reduce the resolution. |
| xRange= |
integer for geographically subsetting by grid indices in the x-direction. By default, no geographical subsetting is done. Example: xRange=(0,80) |
| yRange= |
integer for geographically subsetting by grid indices in the y-direction. By default, no geographical subsetting is done. Example: yRange=(0,80) |
| latLonBounds= |
geographically subset by lat/lon bounds. By default, no subsetting is done. The expected format is (upper left lat, upper left, lon, lower right lat, lower right lon). Example: latLonBounds=(50,-130,20,-65) |
Example:
t850 = loadGrid(filename='C:/Users/myUser/gfs.grb',field='Temperature_Isobaric',level='850 hPa')
The data object returned from loadGrid contains a variety of key:value pairings with information about the data. The list of keys may vary dependent on the type of data, but here is a general list of keys that may be included in the data object returned from loadGrid as well as example values:
| Key |
Example Value |
| globalAttributes |
dictionary of all global attributes included with data |
| level |
850.0 |
| description |
'Temperature @ Isobaric surface' |
| units |
'K' |
| dataSourceName |
file path or URL of data source |
| times |
[2016-03-08T06:00:00Z] |
| filename |
name of file or URL of data source |
| field |
Temperature_isobaric |
| datatype |
float |
| metadataVariables |
dictionary of all metadata variables included with data |
| attributes |
lists all of the attributes of the field/variable loaded |
| projection |
projection information about the data |
| levels |
[850] |
| info |
'Temperature_isobaric K false Temperature @ Isobaric surface' |
| variableAttributes |
lists all of the attributes of the field/variable loaded |
These keys and values can be printed as follows:
t850['description']
The keys and values within one of the dictionary keys (globalAttributes or metadataVariables) can be printed as follows:
t850['globalAttributes']
An individual value of one of the keys in globalAttributes or metadataVariables can be printed as follows
t850['globalAttributes']['file_format']
A practical use for these key:value parings would be to apply it to a layer label. This example adds the description key to the layer label along with the %timestamp% macro:
layer.setLayerLabel(t850['description']+' %timestamp%')