WeatherLink v2 API in Python 3

weatherlink.py

# WeatherLink is a sensor that detects particulate matter in the air
# see https://www.davisinstruments.com

# It is very useful for determining the air quality in your home or office
# The tutorial (https://weatherlink.github.io/v2-api/tutorial) is very good but insufficient
# The code I found online was mostly incomplete, to say the least

import numpy as  np
import pandas as pd
import datetime
import time
import tzlocal
import matplotlib.pyplot as plt

import hashlib
import hmac
import time
import urllib.request
import json

APIKeyv2   = 'get this for your device'
APISecret  = '... and this'


## ----------------------
## Read the stations data
## ----------------------

t               = int(time.time())
message_to_hash = "api-key{}t{}"\
                  .format(APIKeyv2, t)

apiSignature = hmac.new(
  APISecret.encode('utf-8'),
  message_to_hash.encode('utf-8'),
  hashlib.sha256
).hexdigest()

stations_url = "https://api.weatherlink.com/v2/stations?api-key={}&t={}&api-signature={}"\
               .format(APIKeyv2, t, apiSignature)
#print(stations_url,'\n')

with urllib.request.urlopen(stations_url) as url:
    data = json.loads(url.read().decode())
    print(json.dumps(data, indent=4, sort_keys=False))

# in my case, there is only one station
# modifications are required if more than one
station_id   = data['stations'][0]['station_id']
station_name = data['stations'][0]['station_name']
print("\nstation_id:   {}\nstation_name: {}".format(station_id,station_name))

## --------------------------------
## Read the current conditions data
## --------------------------------

t               = int(time.time())
message_to_hash = "api-key{}station-id{}t{}"\
                  .format(APIKeyv2, station_id, t)
#print(message_to_hash)

apiSignature = hmac.new(
  APISecret.encode('utf-8'),
  message_to_hash.encode('utf-8'),
  hashlib.sha256
).hexdigest()

current_url = "https://api.weatherlink.com/v2/current/{}?api-key={}&t={}&api-signature={}"\
              .format(station_id, APIKeyv2, t, apiSignature)
#print(current_url,'\n')

with urllib.request.urlopen(current_url) as url:
    data = json.loads(url.read().decode())
    #print(json.dumps(data, indent=4, sort_keys=True))
    
current_data  = data['sensors'][0]['data'][0]
current_items = ["hum","temp","aqi_val","pm_1","pm_2p5","pm_10"]

item_data = {}
for item in current_items:
    item_data[item] = int(current_data[item])
    
pd.DataFrame(data=item_data,index=[pd.Timestamp(datetime.datetime.today())])

## --------------------
## Read historical data
## --------------------

end_timestamp   = int(time.time())
start_timestamp = end_timestamp - 86400 # maximum: 24 hours

t               = int(time.time())
message_to_hash = "api-key{}end-timestamp{}start-timestamp{}station-id{}t{}"\
                  .format(APIKeyv2, end_timestamp, start_timestamp, station_id, t)
#print(message_to_hash)

apiSignature = hmac.new(
  APISecret.encode('utf-8'),
  message_to_hash.encode('utf-8'),
  hashlib.sha256
).hexdigest()
#print(apiSignature)

historic_url = "https://api.weatherlink.com/v2/historic/{}?api-key={}&t={}&start-timestamp={}&end-timestamp={}&api-signature={}"\
               .format(station_id, APIKeyv2, t, start_timestamp, end_timestamp, apiSignature)
#print(historic_url,'\n')

with urllib.request.urlopen(historic_url) as url:
    data = json.loads(url.read().decode())


df         = pd.DataFrame(data=data['sensors'][0]['data'])       

local_timezone = tzlocal.get_localzone()

df['date'] = [pd.Timestamp(datetime.datetime.fromtimestamp(ts, local_timezone).strftime("%Y-%m-%d %H:%M:%S.%f%z (%Z)")) for ts in df.ts]
df.set_index('date',inplace=True)
df.sort_index(inplace=True)
display(df)

## Plot 24 hours of particulate matter

df.loc[:,['pm_1_avg','pm_2p5_avg','pm_10_avg']].plot(figsize=(20,20))
plt.grid()
plt.axhline(y=12) # PM2.5 max healthy level
plt.show()