how to count data frequency by year and month?

Hi, i want to plot a hsitogram count of stations function of Year/month i have number of station by montn and by year i have 163x20char indicating name of station and time 163x20char in format dd-mmm-yyyy station_code: 405, 406, 500, 501, 430 and time: 02-dec-2010,02-dec-2010,20-may-2009, 06-august-2015, 06-sept-2008 any suggestion please

[Ana Soph]

i want to know too

Answer 1

[Cris LaPierre]

Easier to help if you share your data.

Convert your station name and station code to categoricals. Convert your time to datetime.

Now you can create a histogram of time, grouping the data by station name or station_code. Use dateshift to specify the edges of your histogram bins, with 1 calendar month spacing between edges.

% Create sample data
station = ['my station name 1   ';
'my station name 2   ';
'my station name 3   ';
'my station name 4   ';
'my station name 5   ']

station_code=[405; 406; 500; 501; 430]

% Dates all have to have the same format to be converted to datetimes
% I have therefore edited the last two entries to also use MMM format.
time = {'02-dec-2010','02-dec-2010','20-may-2009', '06-aug-2015', '06-sep-2008'}

% convert station info to categoricals, time to datetime.
station = categorical(string(station))
station_code = categorical(station_code)
time = datetime(time,"InputFormat","dd-MMM-yyyy")

% Specify bin edges
edges = dateshift(min(time),"start","month"):calmonths(1):dateshift(max(time),"start","month","next")

% Create the histogram
histogram(time,edges)

Each bar is one month wide. If you zoom in using the axes toolbar, you'll be able to see the month and year under the bar.