trying to extract the months to create a format looks like 202404, how to do that ?

Date=datetime(raw.textdata(2:end,1),'InputFormat','dd-MMM-yy');%convert the data to date time
yr = year(Date);    % Extract the year
mnth = month(Date); % Extract the month
% Create an array for the year-month combinations
yr_Month = yr * 100 + mnth;%example 202004
% Get unique year-month combinations
u_Months = unique(yr_Month);
%create month label in 'MMM yy" format
m_Labels = strings(length(u_Months), 1);
% Initialize vectors for monthly sums
m_sum_Production = zeros(length(u_Months), 1);
m_sum_T_Consumption = zeros(length(u_Months), 1);
m_sum_O_Consumption = zeros(length(u_Months), 1);
% Calculate the sum for each unique month-year combination
for i = 1:length(u_Months)
    cur_Month = yr_Month == u_Months(i); % Logical index for the current month-year combination
    m_sum_Production(i) = sum(Production(cur_Month)); % Monthly sum of Production
    m_sum_T_Consumption(i) = sum(T_Consumption(cur_Month)); % Monthly sum of Total Consumption
    m_sum_O_Consumption(i) = sum(O_Consumption(cur_Month)); % Monthly sum of Own Consumption
    
    % Generate the corresponding 'MMM yy' label
    yr_Part = floor(u_Months(i) / 100); % Extract the year
    m_Part = mod(u_Months(i), 100);  % Extract the month
    % Create a datetime object for the first day of the month
    m_Date = datetime(yr_Part, m_Part, 1);
    
    % Format month as 'MMM yy'
    m_Labels(i) = datetime(m_Date, 'mmm yy'); % Create the 'MMM yy' label
end         

code is above

Unable to use a value of type datetime as an index.

Error in Q3 (line 15)

mnth = month(Date); % Extract the month

error is above

Answer 1

[Zinea]

Hi @Elisa,

The error above occurs due to the attempt to use a datetime object as an index, which is not allowed. The issue arises from the month function call when it tries to process the Date variable. To resolve this, the following changes need to be made:

1. Remove unnecesary string conversion by directly passing raw.textdata to datetime:

Date = datetime(raw.textdata(2:end, 1), 'InputFormat', 'dd-MMM-yy');

2. Use datestr to directly format the date into 'MMM yy':

m_Labels(i) = datestr(m_Date, 'mmm yy'); % Create the 'MMM yy' label

Given below is the output after the above corrections:

[Elisa]

but it is suggested to not use the in-built function datestr

[Stephen23]

"Use datestr..."

DATESTR is deprecated, as its documentation makes very clear:

It is superfluous anyway, the datetime will get automagically converted when allocated to the string array:

str = "";
str(1) = datetime('now', 'Format','MMM yy')

str = "Oct 24"

Answer 2

[Stephen23]

s = ""; % your string array
dt = datetime('now')

dt = datetime
   09-Oct-2024 13:00:01

dt.Format = 'MMM yy'; % the format given in your example code
s(1) = dt

s = "Oct 24"

dt.Format = 'yyyyMM'; % the format given in your title
s(1) = dt

s = "202410"

If you want to avoid implicit type conversion:

s(1) = compose("%u%02u",dt.Year,dt.Month)

s = "202410"

Answer 3

[Steven Lord]

I would rename the variable you've created called month, as it will prevent you from calling the month function while it exists (or at all in a function, if you define the variable inside that function.)

dt = datetime("today")

dt = datetime
   09-Oct-2024

callMonthFunction = month(dt) % 10

callMonthFunction = 10

month = 42 % define month variable

month = 42

y = month(dt) % error, not 10, as you can't index into the variable with today.

Unable to use a value of type datetime as an index.

month appears to be both a function and a variable. If this is unintentional, use 'clear month' to remove the variable 'month' from the workspace.

Answer 4

[Seth Furman]

The string function takes a format argument. We can specify adjacent year and month in the format with "uuuuMM".

string(datetime(2024,4,1), "uuuuMM")

ans = "202404"