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102 lines
2.8 KiB
Python

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