Find the rate of change of data over specific increments of time

I am working on a project where I need to analyze stock data. I decided to create a graph of the change of stock prices over time. I want the graph to be the rate of change of tesla close prices over one month time intervals. However, I am having trouble creating the rate of change vector as I do not know how to make the intervals work. My data is day by day but I want the vector to be the difference from the currMonth to currMonth-1. I don't have much so far, but if I only had the rate of change vector, plotting everything else would be simple. Basically, I want to graph the first derivative of the close prices in one month increments and display that data of a 10 year range.

Thank you so much.

clear
clc
clf

%import data set TSLA.csv
data = readtable("TSLA_STOCK.csv");

%get vector of tesla close prices
closePrices = data.Close;

%Convert dates into durations
data.MONTH = month(data.Date);
%rate_of_change_of_close_price = diff(closePrices)./diff(data.MONTH)


% create plot with axis labels, title, and grid
%plot(tslaStock.Date, rate_of_change_of_close_price, "-")
%xlim([datetime(2012,11,24,8,40,59)...
%      datetime(2019,4,19,16,40,59)])
%ylim([3 536])
%xlabel('Year') 
%ylabel('TSLA Price')
%title('TSLA price per share vs Time')
%grid on

[Torsten]

It depends on how you want to define the monthly rates of change. The simplest way is to take the values of the first and last day of the months and subtract them. If you want something different, you will have to explain yourself.

[Lukyan]

That was my initial thought, but how do I create a vector as such? I'm very new to matlab so I am having trouble making a function that takes the difference of the first and last day and does it for all the available data.

[Lukyan]

I want my final graph to look like the graph of ROC from this website, using that formula.

Answer 1

[David Hill]

data = readtable('TSLA_STOCK.csv');

Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.

idx=find(diff(month(data.Date)));
monthlyClose=data.Close(idx);
ROV=diff(monthlyClose)./monthlyClose(1:end-1)*100;
plot(ROV)