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Geopointset is the format used by Metview to combine a set of Geopoints variables into a single entity for ease of processing. Thus, a set of observations can be grouped in the same way that fields are grouped into a fieldset variable. For a full list and details of functions and operators on geopoints, see Geopointset Functions. |
Creating a geopointset
A geopointset can be created with the create_geo_set() function, which takes any number of geopoints variables as arguments, or none. Both geopoints and geopointset variables can be concatenated to with a geopointset.
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set1 = create_geo_set() # creates an empty set set2 = create_geo_set(g1, g2, g3) # assuming that g1,g2,g3 are geopoints variables set3 = set1 & g1 & g2 # set3 has 2 geopoints set4 = set2 & set3 # set4 has 5 geopoints |
Operations on geopointsets
Accessing geopintset elements
The The count() function function returns the number of geopoints variables contained by the set.
Use the indexing operator [] to access the geopoints variables contained in a set. For example:
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print(type(set4)) # geopointset
print(count(set4)) # 5
g1 = set4[1] # extract the first item
print(type(g1)) # geopoints
print(count(g1)) # 244 (if there are 244 points in this geopoints variable) |
Operations on geopointsets
As a geopointset is simply a container for geopoints variables, most operations on a geopointset are performed on each of its component geopoints. For example, the following line of code with return a new geopointset where each geopoints variable has had the cos() function applied to its values:
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gsetdiff_r1 = fc_fieldset_5 - gset_5a # gset_5a[n] is subtracted from fc_fieldset_5[n] gsetdiff_r2 = fc_fieldset_5 - gset_1c # gset_1c[1] is subtracted from each field |
Filtering a geopointset
Individual geopoints variables can contain meta-data - see Geopoints for details. To select only those geopoints variables with given meta-data, use the filter() function as described in Geopointset Functions.
The Geopointset file format
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#GEOPOINTSET #GEO # lat lon height date time value # Missing values represented by 3e+38 (not user-changeable) #DATA 69.6523 18.9057 0 20130512 0 100869.8625 63.4882 10.8795 0 20130512 0 100282.3392 63.5657 10.694 0 20130512 0 100241.1666 61.2928 5.0443 0 20130512 0 99852.18932 #GEO # lat lon height date time value # Missing values represented by 3e+38 (not user-changeable) #METADATA param=geopotential #DATA 60.82 23.5 0 20130512 600 101045.8 #GEO # lat lon height date time value # Missing values represented by 3e+38 (not user-changeable) #DATA 55.01 8.41 0 20130513 0 100949.1809 54.33 8.662 0 20130513 0 101027.9101 53.71 7.15 0 20130513 0 100846.619 |
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