Python script to pull PurpleAir data for multiple sensors from the Thingspeak API, combine them, and export a CSV file. To run this script you'll need to adjust the "user config" section, and you may also want to adjust the Thingspeak query parameters starting on row 49.

purpleair.py

import requests # for url requests
from statistics import median # for median of array
import json # for json reading/writing
import time # for epoch timestamp
import csv # for writing csv files

#################################################
# USER CONFIG

data_dir = '/code/data/' # keep trailing slash

# Thingspeak sensor list (two feeds per sensor)
sensors = [
    {
        'id': '813992',
        'key': '0F7FRDWOSFGWETPH'
    },
    {
        'id': '813994',
        'key': '9VPLFBBQDCOSVJWK'
    },
    {
        'id': '813997',
        'key': '4406OWFMIRW4575W'
    },
    {
        'id': '813998',
        'key': 'Z4C30UYGXVX3QY5K'
    }
]

#################################################
# GET DATA

# Make master data objects
data = {}
fields = ['created_at'] # manually add created_at field for csv header mapping

# Iterate through sensor list
for sensor in sensors:

    # Set ID/key
    sensor_id = sensor['id']
    sensor_key = sensor['key']

    url = 'https://api.thingspeak.com/channels/{}/feeds.json'.format(sensor_id)

    # Thingspeak API parameters: https://www.mathworks.com/help/thingspeak/readdata.html
    params = {
        'api_key': sensor_key, # sensor API key
        'days': '7', # days of data to get
        'round': '1', # round decimal places
        'average': '10' # 10 minute averages
        }

    r = requests.get(url, params=params)

    #print(r.url) # print out full URL request with params
    data_raw = r.json()

    ############################
    # Parse sensor data

    fields_sensor = {}
    data_sensor = []

    # Make sensor field list
    for d in data_raw['channel']:
        if d.startswith('field'):
            field_name = data_raw['channel'][d]
            # Add to field sensor mapping
            fields_sensor[d] = field_name
            # Add to master field list
            if field_name not in fields:
                fields.append(field_name)

    # Parse sensor data feeds
    for i, row in enumerate(data_raw['feeds']):
        # Add object to data
        data_sensor.append({})
        for key in row:  
            # Add and rename
            if key in fields_sensor:        
                new_key = fields_sensor[key]
                data_sensor[i][new_key] = row[key]
            # Or just add
            else:
                data_sensor[i][key] = row[key]

    '''
    # Check field mapping
    print(data_raw['feeds'][0])
    print(data_sensor[0])
    '''

    ############################
    # Add sensor data to master data dictionary
    for row in data_sensor:
        created_at = row['created_at']

        # Make new timestamp object if needed
        if created_at not in data:   
            data[created_at] = {}

        # Add to timestamp object
        for key in row:
            # If key exists, append to value list
            if key in data[created_at]:
                data[created_at][key].append(row[key])
            # Else make new value list
            else:    
                data[created_at][key] = [row[key]]

#################################################
# Make CSV file

# Make csv data array with median values
data_csv = []

for timestamp in data:
    row = data[timestamp].copy()
    # For each key
    for key in row:
        # Collapse value list to median, or take first value (for date strings or None)
        try:
            row[key] = median(map(float, row[key]))
        except:
            row[key] = row[key][0] 
    # Append to array
    data_csv.append(row)

# Write to CSV file
with open(data_dir + 'purpleair.csv', 'w', newline='') as f:
    writer = csv.DictWriter(f, fieldnames=fields)
    # Write header
    writer.writeheader()
    # Write rows
    for row in data_csv:
        empty = True
        # Check if empty row
        for key in row:
            if key != 'created_at' and row[key]:
                empty = False 
        # If not empty row
        if empty == False:
            writer.writerow(row)