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How to count date occurrence independently of year?
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Hi,
I have an excel file with about 6000 dates from year 1900 and until now. I want to plot the occurrence of dates irrespective of year to see if the occurrence is dependent of time of year. How can I do this? The excel file is attached.
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Accepted Answer
Adam Danz
on 12 Sep 2019
Edited: Adam Danz
on 13 Sep 2019
This solution creates a table (T) that lists all month-day combinations in your data in 1 column and the count in the 2nd column. It also produces a plot showing the frequency of month-day combinations (ignore the year label). See comments for details.
% Read in the dates as datetime
m = readmatrix('Dates.xlsx','OutputType','datetime');
% Remove missing vals and sort dates
% (sort isn't really needed but makes it easier to look at the vector)
m = sort(m(~isnat(m)));
% find day-of-year number
doy = day(m,'dayofyear');
% count number of doy's
binEdges = 0:1:max(doy);
mdCount = histcounts(doy,binEdges);
% list all possible [month,day] values (we'll use them as labels)
allPossibleDates = (min(m):max(m)).';
mdAllPossible = unique([month(allPossibleDates), day(allPossibleDates)], 'rows');
allPossible = datetime(1904,mdAllPossible(:,1),mdAllPossible(:,2),'Format', 'MM/dd'); % Year must be any leap year
% Put results in summary table
T = table(allPossible(:), mdCount(:),'VariableNames', {'MonthDay', 'count'});
figure();
axh = axes();
plot(axh, T.MonthDay,T.count)
axh.XAxis.TickLabelFormat = 'MM-dd'; %reformat x ticks if you want mm/dd
xlabel('Day of year (mm-dd)')
ylabel('Count')
title(sprintf('Data from %s to %s',datestr(min(m),'mm/dd/yyyy'),datestr(max(m),'mm/dd/yyyy')))
Result:
head(T) % show the first few rows of table
ans =
8×2 table
MonthDay count
________ _____
01/01 0
01/02 34
01/03 34
01/04 24
01/05 24
01/06 27
01/07 13
01/08 32
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More Answers (1)
Jacob Ward
on 12 Sep 2019
This is a cool way of visualizing it as well:
clear;
dates = readtable('C:\Users\jacob\Downloads\Dates.xlsx','ReadVariableNames',false);
for n = 1:5902
datesSplitIntoParts(n,:) = double(split(string(dates{n,1}),'/'));
end
figure('Units','Normalized','Position',[0.1 0.1 0.8 0.8])
histogram2(datesSplitIntoParts(:,1),datesSplitIntoParts(:,2))
xlabel('Month')
set(gca,'XTick',[1:12],...
'XTickLabel',{'January','February','March','April','May','June',...
'July','August','September','October','November','December'})
ylabel('Day')
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