Help me to do difficult tasks in MATLAB

Good day, friends! :)

I have no idea how to work in MATLAB, but I need to do some tasks. I have file named "airtempt.mat". When I open it in MATLAB I see in workspace 3 data elements (air 1 (value 1460x1 doubled) , air 2 (value 1460x1 doubled) and t (value 1460x1 doubled)), Then I shoud to do 2 tasks. But i cannot do it, becouse it's my first time in MATLAB and i want to know how can I do it and very need your assistance please (if it possible write MATLAB code to illustrate me how it is working) :)

Here it is:

"

• Assignment: Statistic Tests

Introduction:

Below each question, please insert MATLAB codes (functions, commands) that you use to solve that question and copy the MATLAB outcomes. Please insert the required figures below the questions, and the figures should be clear and informative.

Load the data file “airtemp.mat” into MATLAB. You can either double click the file, or use command “load airtemp.mat”. Then you will see 3 variables in MATLAB:

air1: Air temperatures every 6 hours for entire year of 2013, at Station SEATS in the South China Sea (18°N, 118°E);

air2: Air temperatures every 6 hours for entire year of 2013, at a location in Sahara Desert (18°N, 20°E);

t: time of each data point in number of days in the year.

Question 1. (C5, CLO3, PLO6)

Consider how to code a MATLAB function to calculate moving average of a variable x:

y = mvavg(x, n),

in which n is the number of data points used for calculating each average. Then, evaluate the daily moving average of air1 and air2 using your coded function.

If you don’t know “moving average”, please check its definition on Internet. You must note that “daily moving average” is differentfrom “daily average”!

Plot on one figure including air1, air2 and their daily moving averages over time. (hint: you can also calculate daily moving average for t, so that the number of elements in the moving average of air1, air2 and t is same.)

Question 2. (C5, CLO3, PLO6)

Plot temperature of the two stations over time on one figure, using markers, no connecting lines. Requirements:

• if the average temperature of one day (“today”) is higher than the day before by more than 1 degree (i.e. T_today – T_yesterday > 1), then ALL the 4 data points of “today” use red color;
• if the average temperature of one day (“today”) is lower than the day before by more than 1 degree (i.e. T_yesterday – T_today > 1), then ALL the 4 data points of “today” use blue color;

• if the difference between T_today and T_yesterday is no more than 1 degree, all the 4 data points of “today” use black color (you can also use black color for the markers of the first day).
• Assess the differences in the temperature patterns between the two sites. Please explain possible reasons for the differences."

[Dyuman Joshi]

"I have no idea how to work in MATLAB, but I need to do some tasks."

"But i cannot do it, becouse it's my first time in MATLAB and i want to know how can I do it"

I strongly recommend you to take the free introductory course - MATLAB Onramp to learn the essentials of MATLAB.

After you go through the course, you should be able to write a code. Then, if you are having a probelm, show us the code you've written to try to solve the problem and ask a specific question about where you're having difficulty.

And the assignment also has hints included in it, so that would be helpful as well.

Answer 1

[Suzur]

CHAT GPT write me this, but it doesn't work:

For question 1, you need to write a function that calculates the moving average of a vector x using a window of size n. Here is one possible way to do that:

function y = mvavg(x,n)

% MVAVG Moving average of a vector

% Y = MVAVG(X,N) returns a vector Y of the same length as X, where each element of Y is the average of N consecutive elements of X centered at the corresponding position. If the window size is larger than the available elements at the ends, the average is taken over the existing elements only.

% Initialize output vector

y = zeros(size(x));

% Loop over each element of x

for i = 1:length(x)

% Find the indices of the window

idx = i-n/2:i+n/2;

% Remove indices that are out of bounds

idx = idx(idx > 0 & idx <= length(x));

% Calculate the average of the window

y(i) = mean(x(idx));

end

end

To use this function, you need to save it in a file named mvavg.m in your current folder or MATLAB path. Then you can load the data file airtemp.mat and call the function on the variables air1, air2, and t. For example:

load airtemp.mat % Load the data

n = 4; % Number of data points per day

y1 = mvavg(air1,n); % Moving average of air1

y2 = mvavg(air2,n); % Moving average of air2

yt = mvavg(t,n); % Moving average of t

To plot the original data and the moving averages on one figure, you can use the plot function with different line styles and colors. For example:

plot(t,air1,'b-',yt,y1,'b--',t,air2,'r-',yt,y2,'r--') % Plot the data

xlabel('Time (days)') % Label the x-axis

ylabel('Temperature (°C)') % Label the y-axis

legend('air1','air1 (moving average)','air2','air2 (moving average)') % Add a legend

For question 2, you need to plot the temperature of the two stations over time using different colors depending on the daily change. To do this, you can use a loop to check the daily average temperature and assign a color to each day. Then you can use the scatter function to plot the data with markers. For example:

% Initialize color vectors

c1 = zeros(length(t),3); % Color vector for air1

c2 = zeros(length(t),3); % Color vector for air2

% Loop over each day

for i = 1:n:length(t)

% Find the indices of the day

idx = i:i+n-1;

% Remove indices that are out of bounds

idx = idx(idx <= length(t));

% Calculate the average temperature of the day

T1 = mean(air1(idx)); % Average temperature of air1

T2 = mean(air2(idx)); % Average temperature of air2

% Compare the average temperature with the previous day

if i > n % If not the first day

% Calculate the difference with the previous day

dT1 = T1 - mean(air1(i-n:i-1)); % Difference for air1

dT2 = T2 - mean(air2(i-n:i-1)); % Difference for air2

% Assign a color based on the difference

if dT1 > 1 % If air1 increased by more than 1 degree

c1(idx,:) = repmat([1 0 0],length(idx),1); % Red color

elseif dT1 < -1 % If air1 decreased by more than 1 degree

c1(idx,:) = repmat([0 0 1],length(idx),1); % Blue color

else % If air1 changed by no more than 1 degree

c1(idx,:) = repmat([0 0 0],length(idx),1); % Black color

end

if dT2 > 1 % If air2 increased by more than 1 degree

c2(idx,:) = repmat([1 0 0],length(idx),1); % Red color

elseif dT2 < -1 % If air2 decreased by more than 1 degree

c2(idx,:) = repmat([0 0 1],length(idx),1); % Blue color

else % If air2 changed by no more than 1 degree

c2(idx,:) = repmat([0 0 0],length(idx),1); % Black color

end

else % If the first day

% Assign black color

c1(idx,:) = repmat([0 0 0],length(idx),1); % Black color

c2(idx,:) = repmat([0 0 0],length(idx),1); % Black color

end

end

% Plot the data with markers and colors

scatter(t,air1,[],c1,'filled') % Plot air1

hold on % Hold the figure

scatter(t,air2,[],c2,'filled') % Plot air2

hold off % Release the figure

xlabel('Time (days)') % Label the x-axis

ylabel('Temperature (°C)') % Label the y-axis

legend('air1','air2') % Add a legend

The temperature patterns of the two sites are very different. The station in the South China Sea has a relatively stable and moderate temperature throughout the year, with small daily and seasonal variations. The station in the Sahara Desert has a large diurnal cycle, with high temperatures during the day and low temperatures at night. It also has a seasonal cycle, with higher temperatures in summer and lower temperatures in winter. The possible reasons for the differences are related to the different geographic and climatic conditions of the two sites. The South China Sea is a large body of water that has a high heat capacity and can moderate the temperature of the surrounding air. The Sahara Desert is a dry and arid land that has a low heat capacity and can heat up or cool down quickly. The South China Sea is also influenced by the monsoon winds that bring moisture and clouds, which can affect the radiation balance and the temperature. The Sahara Desert is under the influence of the subtropical high pressure, which prevents cloud formation and allows more solar radiation to reach the surface.

[Dyuman Joshi]

"CHAT GPT write me this, but it doesn't work:"

ChatGPT is not a reliable (programming) resource.

Answer 2

[Image Analyst]

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To get a moving average you can use movmean