JSON format from the API

Hello, I'm going to fetch data from the OpenWeatherMap website as an app designer. The API will be in JSON format, but I keep getting errors. Can you help?

[Rik]

You should post the code and run it here, or at least the actual error.

[Mert]

I could not solve this problem

Please help me

Write a MATLAB function (fetchFiveDayForecast) that retrieves city-based weather data from the OpenWeatherMap API. This function should pull data in JSON format from the API and process this data to convert it into a format that can be utilized within MATLAB.

[Rik]

Sounds like homework to me. What code did you try?

Answer 1

[Abhishek Kumar Singh]

Hi @Mert,

I generated an API key from https://home.openweathermap.org/api_keys and tried a simple MATLAB function, from which I was able to retrieve data without any errors.

Refer to the MATLAB function code below:

function getWeatherForecast(cityName, apiKey)

    % Construct the API request URL
    url = ['http://api.openweathermap.org/data/2.5/forecast?q=', cityName, '&appid=', apiKey, '&units=metric'];

    try
        % Send the request and get the response
        responseData = webread(url);
        
        % Process and display the temp for the first time point
        firstTemp = responseData.list{1}.main.temp;
        disp(['First temperature forecast for ', cityName, ' is: ', num2str(firstTemp), ' Celsius']);
    catch ME
        % Error handling
        disp('Failed to retrieve or process weather data.');
        disp(['Error: ', ME.message]);
    end
end

You can call the function as:

% cityName - Name of the city (string)
% apiKey - Your OpenWeatherMap API key (string)
getWeatherForecast('London', 'YOUR_API_KEY')

The API gives you a lot of information organized in lists. You'll need to think about how you want to use this information and might need to add more steps to work with it properly. Here's a quick look at what kind of data you get from the API:

K>> responseData.list{1}

ans =

struct with fields:

dt: 1.7166e+09

main: [1×1 struct]

weather: [1×1 struct]

clouds: [1×1 struct]

wind: [1×1 struct]

visibility: 10000

pop: 0.3100

sys: [1×1 struct]

dt_txt: '2024-05-25 15:00:00'

K>> responseData.list{1}.main

ans =

struct with fields:

temp: 20.0400

feels_like: 19.4800

temp_min: 19.8100

temp_max: 20.0400

pressure: 1015

sea_level: 1015

grnd_level: 1012

humidity: 53

temp_kf: 0.2300

K>> responseData.list{1}.main.temp

ans =

20.0400

I hope this helps you get preliminary idea of how to get started. You can further process and visualize the forecast data in various formats within MATLAB.

[Mert]

I tried something but I have an error, This is my code and I gave an error.Can you check ?

error is : Undefined function 'fetchFiveDayForecast' for input arguments of type 'char'.

methods (Access = private)

function weatherData = fetchFiveDayForecast(cityName,apiKey)
baseURL = 'http://api.openweathermap.org/data/2.5/forecast';
query = sprintf('%s?q=%s&units=metric&appid=%s', baseURL, cityName, apiKey);
data = webread(query);


temperature = data.list.main.temp;
humidity = data.list.main.humidity;
windSpeed = data.list.wind.speed;

end
end

function GetInformationButtonPushed(app, event)
cityName = app.SelectCityDropDown.Value;
apiKey = 'myAPİ';
weatherData = fetchFiveDayForecast(cityName, apiKey);
plot(app.TemperatureAxes, weatherData.temperature);
title(app.TemperatureAxes, sprintf('Temperature Forecast for %s', cityName));
ylabel(app.TemperatureAxes, 'Temperature (°C)');
plot(app.HumidityAxes,weatherData.humidity);
title(app.HumidityAxes, sprintf('Humidity Forecast for %s', cityName));
ylabel(app.HumidityAxes, 'Humidity (%)');
plot(app.WindSpeedAxes, weatherData.windSpeed);
title(app.WindSpeedAxes, sprintf('Wind Speed Forecast for %s', cityName));
ylabel(app.WindSpeedAxes, 'Wind Speed (m/s)');
currentWeather = weatherData(1, :);
app.TemperatureLabel.Text = sprintf('Temperature: %.1f °C', currentWeather.temperature);
app.HumidityLabel.Text = sprintf('Humidity: %.0f%%', currentWeather.humidity);
app.WindSpeedLabel.Text = sprintf('Wind Speed: %.2f m/s', currentWeather.windSpeed);

end 

[Abhishek Kumar Singh]

Can you replace the line:

weatherData = fetchFiveDayForecast(cityName, apiKey);

with:

weatherData = app.fetchFiveDayForecast(cityName, apiKey);

and try again?

Let me know how it goes.