update the dashboard download class

floenavi/polarstern.py

@@ -6,7 +6,8 @@
 __author__ = "Stefan Hendricks"
 
 import requests
-from datetime import datetime
+from dateutil.parser import parse as dtparse
+from datetime import datetime, timedelta
 from pathlib import Path
 from loguru import logger
 import numpy as np
@@ -16,26 +17,28 @@ from icedrift import GeoReferenceStation
 
 class PolarsternAWIDashboardPos(object):
 
-    def __init__(self, begin_date=None, end_date=None, output="csv"):
+    def __init__(self, begin_date, end_date, time_pad_minutes=10):
         """
+        Get Polarstern position and heading from the Polarstern HYDRINS1 sensor
+        NOTE: The URL etc can be checked using the web interface at
+              https://dashboard.awi.de/data-xxl/index.html
+        :param begin_date: (datetime.datetime) Start of the requested temporal coverage
+        :param end_date: (datetime.datetime)Start of the requested temporal coverage
+        :param time_pad_minutes: (integer) The number of minutes the period will be extended
+            on both side to ensure the data coverage of Polarstern position and heading
+            data always fully comprised the requested data period
 
-        :param begin_date:
-        :param end_date:
-        :param output:
         """
 
-        # Save input arguments
-        self.begin_date = begin_date
-        self.end_date = end_date
-        self.output = output
-
+        # Save input arguments and automatically extend data period
+        # using a short time window to ensure that there is always
+        # Polarstern data before the requested data period.
+        self.begin_date = begin_date - timedelta(minutes=time_pad_minutes)
+        self.end_date = end_date + timedelta(minutes=time_pad_minutes)
         # --- Properties ---
 
         # The format of the REST output.
-        # NOTE: The (default) value is specified in the `output` keyword to this method
-        self.format_dict = {"csv": "text/csv",
-                            "json": "application/json",
-                            "tab": "text/tab-separated-values"}
+        self.requested_format = "text/csv",
 
         # Output format for the time stamp
         # NOTE: Most sensors do not report faster than 1 second, therefore there is no need
@@ -45,36 +48,70 @@ class PolarsternAWIDashboardPos(object):
         # The main URL to the dashboard REST interface
         self.base_url = "https://dashboard.awi.de/data-xxl/rest/data"
 
-        # A list of sensors
+        # Parameter to be pulled from the Polarstern Inertial Navigation Unit
+        # 1. Latitude
+        # 2. Longitude
+        # 3. True Heading
         self.sensors = ["vessel:polarstern:hydrins_1:latitude$NRT",
                         "sensors=vessel:polarstern:hydrins_1:longitude$NRT",
                         "sensors=vessel:polarstern:hydrins_1:heading$NRT"]
 
-        # Temporal resolution:
+        # Temporal resolution (full)
         self.aggregate_value = "second"
 
-    def save(self, filename=None):
-        """
+        # Load the data
+        self.response = None
+        self.download()
 
-        :param filename:
+        self._variables = {}
+        self.decode_response()
+
+    def download(self):
+        """
+        Pulls the data for the requested period from dashboard.awi.de
         :return:
         """
 
         # Construct the URL
         url = self._construct_url()
-        logger.debug("url=%s" % url)
+        logger.info("data request url: {}".format(url))
 
         # Download the websites response
         # TODO: Error management
         r = requests.get(url)
 
         # Post-process the content
-        ascii_content = "\n".join(r.text.splitlines())
-        if self.output == "csv":
-            ascii_content = ascii_content.replace(";", ",")
+        self.response = "\n".join(r.text.splitlines())
+        self.response = self.response.replace(";", ",")
 
-        # Write output file
-        open(filename, 'w').write(ascii_content)
+    def decode_response(self):
+        """
+        Parses the response from the data service into arrays of time, longitude, latitude
+        and true heading.
+        :return:
+        """
+
+        # Init the variables
+        # NOTE: the first line is the header line and has to be ignored.
+        lines = self.response.split("\n")[1:]
+        n_lines = len(lines)
+        self._variables["time"] = np.full(n_lines, object)
+        for parameter_name in ["longitude", "latitude", "heading"]:
+            self._variables[parameter_name] = np.full(n_lines, np.nan)
+
+        for i, line in enumerate(lines):
+            string_array = line.split(",")
+            self._variables["time"][i] = dtparse(string_array[0])
+            self._variables["latitude"][i] = np.float(string_array[1])
+            self._variables["longitude"][i] = np.float(string_array[2])
+            self._variables["heading"][i] = np.float(string_array[3])
+
+    def save(self, filename):
+        """
+        :param filename:
+        :return:
+        """
+        raise NotImplementedError()
 
     def _construct_url(self):
         """
@@ -89,18 +126,18 @@ class PolarsternAWIDashboardPos(object):
         url += self.sensor_def
 
         # add output format
-        url += "&format=%s" % self.format_dict[self.output]
+        url += "&format=%s" % self.requested_format
 
         # add temporal resolution
         url += "&aggregate={}".format(self.aggregate_value)
 
         # add begin date (optional)
         if self.begin_date is not None:
-            url += "&beginDate=%s" % self.begin_date.strftime(self.datetime_format)
+            url += "&beginDate={}".format(self.begin_date.strftime(self.datetime_format))
 
         # add end date (optional)
         if self.end_date is not None:
-            url += "&endDate=%s" % self.end_date.strftime(self.datetime_format)
+            url += "&endDate={}".format(self.end_date.strftime(self.datetime_format))
 
         return url
 
@@ -113,6 +150,26 @@ class PolarsternAWIDashboardPos(object):
         sensor_def = "sensors="+"&".join(self.sensors)
         return sensor_def
 
+    @property
+    def reference_station(self):
+        """
+        Return a icedrift.GeoReferenceStation instance
+        :return:
+        """
+        refstat = GeoReferenceStation(self.time, self.longitude, self.latitude, self.heading)
+        return refstat
+
+    def __getattr__(self, attr):
+        """
+        Modify the attribute getter to provide a shortcut to the data content
+        :param attr:
+        :return:
+        """
+        if attr in list(self._variables.keys()):
+            return self._variables[attr]
+        else:
+            raise AttributeError()
+
 
 class PolarsternPOSDashboardData(object):
     """
@@ -180,5 +237,3 @@ class PolarsternPOSDashboardData(object):
         data = GeoReferenceStation(content["time"], content["longitude"], content["latitude"], content["heading"])
 
         return data
-
-