examples/simple_model_tstd.py

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from os import path
import urllib

import ocw.data_source.local as local
import ocw.evaluation as evaluation
import ocw.metrics as metrics
import ocw.plotter as plotter

# File URL leader
FILE_LEADER = "http://zipper.jpl.nasa.gov/dist/"
# One Local Model Files
FILE_1 = "AFRICA_KNMI-RACMO2.2b_CTL_ERAINT_MM_50km_1989-2008_tasmax.nc"

# Filename for the output image/plot (without file extension)
OUTPUT_PLOT = "knmi_temporal_std"

# Download necessary NetCDF file if needed
if path.exists(FILE_1):
    pass
else:
    urllib.urlretrieve(FILE_LEADER + FILE_1, FILE_1)

""" Step 1: Load Local NetCDF File into OCW Dataset Objects """
print "Loading %s into an OCW Dataset Object" % (FILE_1,)
# 'tasmax' is variable name of values
knmi_dataset = local.load_file(FILE_1, "tasmax")

print "KNMI_Dataset.values shape: (times, lats, lons) - %s \n" % (knmi_dataset.values.shape,)

# Acessing latittudes and longitudes of netCDF file
lats = knmi_dataset.lats
lons = knmi_dataset.lons

""" Step 2:  Build a Metric to use for Evaluation - Temporal STD for this example """
# You can build your own metrics, but OCW also ships with some common metrics
print "Setting up a Temporal STD metric to use for evaluation"
std = metrics.TemporalStdDev()

""" Step 3: Create an Evaluation Object using Datasets and our Metric """
# The Evaluation Class Signature is:
# Evaluation(reference, targets, metrics, subregions=None)
# Evaluation can take in multiple targets and metrics, so we need to convert
# our examples into Python lists.  Evaluation will iterate over the lists
print "Making the Evaluation definition"
# Temporal STD Metric gets one target dataset then reference dataset should be None
std_evaluation = evaluation.Evaluation(None, [knmi_dataset], [std])
print "Executing the Evaluation using the object's run() method"
std_evaluation.run()

""" Step 4: Make a Plot from the Evaluation.results """
# The Evaluation.results are a set of nested lists to support many different
# possible Evaluation scenarios.
#
# The Evaluation results docs say:
# The shape of results is (num_metrics, num_target_datasets) if no subregion
# Accessing the actual results when we have used 1 metric and 1 dataset is
# done this way:
print "Accessing the Results of the Evaluation run"
results = std_evaluation.unary_results[0][0]
print "The results are of type: %s" % type(results)

# From the temporal std output I want to make a Contour Map of the region
print "Generating a contour map using ocw.plotter.draw_contour_map()"

fname = OUTPUT_PLOT
gridshape = (4, 5) # 20 Years worth of plots. 20 rows in 1 column
plot_title = "TASMAX Temporal Standard Deviation (1989 - 2008)"
sub_titles = range(1989, 2009, 1)

plotter.draw_contour_map(results, lats, lons, fname,
                         gridshape=gridshape, ptitle=plot_title,
                         subtitles=sub_titles)