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102 lines
2.8 KiB
Python
102 lines
2.8 KiB
Python
"""Get latest observations from Port Authority of NSW and update local copy.
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Station IDs are below:
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02: Offshore (Directional) Wave
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03: Bombora (Directional) Wave
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04: Captain Cook Channel (SG) Wave
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05: Kurnell (SG) Wave
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06: Molineaux Point Wind
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07: Sydney Airport (Main Runway BOM) Wind
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08: Brotherson Emergency Response Jetty Tide
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09: Caltex (Directional) Current
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12: Western Wedding Cake Wind
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13: Fort Denison (Sth end BOM) Wind
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14: Overseas Passenger Terminal Wind
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15: Glebe Island Wind
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16: Fort Denison-Primary (Nth end) Tide
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17: Fort Denison-Secondary (Vegapuls64) Tide
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18: Circular Quay ADCP Current
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19: Balls Head Current
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22: Twofold Bay - Munganno Point Wave
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23: Twofold Bay - Multipurpose Wharf Wind
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24: Breakwater Wharf Wind
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27: Middle Wall (Vegapulse WL61) Tide
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28: Goodwood (Vegapulse WL61) Tide
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"""
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import os
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import re
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import datetime
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import requests
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import pandas as pd
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from lxml import html
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# Set station as Fort Denison tide
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stn_id = 16
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output_dir = 'csv'
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def update_master(output_dir, csv_name, df):
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"""Update master csv time series.
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Args:
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output_dir (str): path to time series directory
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csv_name (str): name of time series file
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df (dataframe): dataframe with datetime index
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Returns:
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None
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"""
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try:
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# Load local master table if it exists
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master = pd.read_csv(os.path.join(output_dir, csv_name),
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index_col=0,
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parse_dates=True)
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# Only include timestamps that do not already exist
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df = df[~df.index.isin(master.index)]
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# Update master
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master = master.append(df)
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except FileNotFoundError:
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# Create new master table if none exists
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master = df
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# Export master table
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master.to_csv(os.path.join(output_dir, csv_name))
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# Get main page
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url = 'http://wavewindtide.portauthoritynsw.com.au/'
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page = requests.get(url)
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tree = html.fromstring(page.content)
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# Get elements from selected station
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t_raw = tree.get_element_by_id(f'MainContent_ctl{stn_id:02}_lblRecordDate')
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meas = tree.get_element_by_id(f'MainContent_ctl{stn_id:02}_lblSummary')
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description = tree.get_element_by_id(f'MainContent_ctl{stn_id:02}_lblTitle')
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# Parse column names
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text = re.split(':\s|(m|s|knots|deg)\s', meas.text + ' ')
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parts = [t for t in text if t]
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parameters = [p.strip() for p in parts[::3]]
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values = [float(p) for p in parts[1::3]]
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units = parts[2::3]
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columns = [f'{p} ({u})' for p, u in zip(parameters, units)]
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# Parse time
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time = re.search('at ([0-9]{4})', t_raw.text).group(1)
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date = t_raw.text.split(',')[1].strip()
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t = datetime.datetime.strptime(date + time, '%d %b %Y%H%M')
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# Create dataframe
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df = pd.DataFrame({c: v for c, v in zip(columns, values)}, index=[t])
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df.index.name = 'datetime'
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# Update master dataframe
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csv_name = description.text + '.csv'
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update_master(output_dir, csv_name, df)
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