I have a time-series containing 900 entries, stored in a 900x2 matrix (first column are datenumbers converted from excel e.g. 732994 to represent 13-nov-2006, second column is the reading at each day) I would like to plot them out with the years marked out on the x-axis, using the datestr function.
here is my code segment.
x=newsgdata(:,1);
x=num2str(x); %converts datenumbers from int to string
dateline=datetick('x','yyyy');
plot(dateline,newsgdata(:,2))
when i run this code, i get the error: Error using datetick Too many output arguments.
I have tried running plot(datetick('x','yyyy'),newsgdata(:,2)) but the same error keeps popping up.
First, plot vs the datenum directly:
plot(newsgdata(:,1), newsgdata(:,2));
Then, use datetick to convert the labels from datenums to strings.
datetick('x', 'yyyy')
Related
I have a table which contains the year and the month in a "double" format.
I then create a datenum for each entry in the table:
for j=1:number_of_rows
dates_returns_all_period_monthly(j,10)=datenum([year,month,1]);
end
First of all, is there a way to have the dates on a monthly basis without having to set the day on the datenum command?
Secondly, the previous commands give me values such as 731947 for
I then want to get the date in a date format,
I am trying to run the following command:
dates_returns_all_period_monthly(j,11)=datestr(dates_returns_all_period_monthly(j,10));
but I get an error "Assignment has more non-singleton rhs dimensions than non-singleton subscripts"
How can I fix this? Ideally I would like to have something like January 2004, February 2005, etc.. or 01/2004, 02/2004, something like that, because later on I want to plot with the dates on the x-axis, and I don't want to have 731947 etc. as values.
The problem here is that you are trying to put a string output into a matrix array. This won't work: it will try and convert the string to an array of numbers, and your indexing will tell it to try to put your array of numbers into a single matrix location, causing the error that you are seeing.
What you'll need to do if you wish to store them is to create a cell array, which store arbitrary data inside each element location, but require different syntax to access:
text_dates = cell(1,number_of_rows);
for j=1:number_of_rows
text_dates{j}=datestr(dates_returns_all_period_monthly(j,10));
end
You won't be able to use these directly as part of the plot command however - Matlab needs inputs to plot to be numeric, so strings will not work. What you want to do is create your plot using your numeric values, then access the current axis properties (you can use the gca command to get this) and change the `XTickLabel' properties to the strings you wish, e.g.:
plot(dates_returns_all_period_monthly(:,10),whatever_your_y_values_are);
ax=gca;
set(gca,'XTickLabels',text_dates);
I have a matrix that contains two columns of data. The first column has timestamps given in UNIX time and the second column has a corresponding data set.
I'm trying to plot this DATA with human-readable times on the bottom axis.
I've plotted the raw data, like so:
plot(DATA(:,1), DATA(:,2));
I know there is a timeseries() function in MATLAB, but I can't seem to get it working correctly. I should be able to plot the data, following the MATLAB documentation.
I've tried declaring the first column as a time series:
TS = timeseries(DATA(:,1));
Then I tried plotting the data, like so:
plot(TS, DATA(:,1));
Although this approach seems to make rational sense, I get the following error:
Error using plot
Data must be a single matrix Y or a list of pairs X,Y
I also tried to use the addsample() function to append the data to the time series and then plot it.
K = addsample(TS, DATA(:,2));
plot(K);
But doing this produced the following error:
A new sample must be specified either as a structure or by Property-Value pairs.
So how do I plot this time data correctly? Thank you!
I work quite often with posix time (i.e. unixtime) with other programs, but in matlab the easiest format to deal with time and date is the Matlab time serial number format.
To convert from Unix to Matlab I use a small conversion function extensively:
function matlabtime = unix2matlabtime(unixtime)
%// function matlabtime = unix2matlabtime(unixtime)
%//
%// input : ** unixtime ** : time vector in the UNIX time serial number
%// representation (seconds since 01-jan-1970)
%//
%// output : ** matlabtime ** : time vector in the Matlab time serial number
%// representation (days since 01-jan-0000)
pivot = datenum([1970 01 01 00 00 00]) ;
matlabtime = ( unixtime / 24 / 3600 ) + pivot ;
with this function saved somewhere on your path, you can plot your data like so:
%// Generate sample data
sampleunixtime = linspace( 1427205640 , 1427205900 ).' ; %'// ignore this comment
DATA = [sampleunixtime , sin(sampleunixtime./10) ] ;
%// get a time vector in Matlab time serial format, then plot
time = unix2matlabtime( DATA(:,1) ) ;
plot( time, DATA(:,2) )
%// Adjust X-Ticks in human readable format
set( gca , 'XTickLabel' , datestr( get(gca,'XTick'),'HH:MM:SS' ) )
To obtain:
look at the datenum and datestr documentation to see how to handle these. There are many predefined output format for the date/time or you can even build your own to refine to the precision you need (add millisecond, remove seconds, add the date etc ...).
Just be aware that the XTickLabel are now overriden, so they will not be updated automatically. So if you zoom or pan on your figure you'll have to re-run the last line of code to refresh the XTicks values.
(personally, I put this last line of code in a Matlab toolbar shortcut to have quick access to it at any time).
I have a 356*2 array lets call him tmp
When the (:,1) is in milisecs
Now i am looking to make a plot of X over y when i want the X be showed in HH:MM:SS.FFF secs
I have converted the secs to that format by
datestr(tmp(:,1)*0.001/24/3600,'HH:MM:SS.FFF')
But this is a string, how can i use it in my plot function
You can apply what are called date format strings to the axes of plots with built-in function datetick. For example, with your first column being time, you could call
plot(tmp(:, 1), tmp(:, 2))
to plot the data. Then call:
datetick('x', 'HH:MM:SS.FFF')
to format the values assigned to ticks on the x-axis based on the second input argument. NOTE that, in order to perform this conversion, the function assumes that the time data is in units of DAYS, so if your data is in milliseconds, you should divide your time data by (24*60*60*1000). Note also that when you zoom on this graph, the new labels will not be re-written at each scale as numeric ones would have been. To get around this, I thoroughly recommend datetickzoom from the MATLAB file exchange.
Use your original value of tmp(:,1) for the plot function and then use your datestr(tmp(:,1)*0.001/24/3600,'HH:MM:SS.FFF') as the label?
I have a bunch of time-indexed data, that I have to plot with MATLAB.
The current format of the time is as follows
23:55:42,-147928.686833054
23:55:43,-147928.404621219
23:55:44,-147928.219419702
23:55:45,-147928.395802099
23:55:46,-147928.492812417
23:55:47,-147928.413440339
23:55:48,-147928.386982979
I simply wish to plot the second column, the values, against the first column, the time.
I can of course take the first time point as 0, and next as 1, ..., and so on. However, I wish to stick with the original timing.
How may I deal with this type of time handily?
Convert your time values using datenum. Create an X-Y plot in the usual way. And ask for time-formatted labels with
datetick('x', 13)
For example:
plot(datenum(a(:,1)), a(:,2));
datetick('x', 13)
Try the property "XTickLabel" after plotting.
You can use it with a cell of strings of your data:
plot(second-column-values)
Times={'23:55:42','23:55:43',...}
set(gca,'XTickLabel',Times)
I have data like this:
22.10.1980. 100
25.10.1980. 120
26.10.1980. 12
(only much more of it, and for each date, several independent measurements on the right).
Now, this is probably trivial, but I've never done anything like it in MATLAB, and am having problems finding similar examples online. I need to plot the data on a time/showing dates axis (x axis), with all dates inside (so, 23. and 24. as well ... for which I don't have measurements).
How can I get dates to show up on a plot axis?
It seems like it might be the best to use datetick.
Usage: datetick('x') or datetick('x', dateformat) with the available formats as explained in the documentation.
Assuming your data file has the format given above, you could use textscan to read the data:
fid = fopen('data.txt','rt');
C = textscan(fid,'%s %s %s %d','Delimiter','.','CollectOutput',1);
fclose(fid);
The first cell of C will contain an N-by-3 cell array of strings (the parts of the date) and the second cell of C will contain an N-by-1 vector of the data measurements. You can create a date number for each measurement by first concatenating the 3 smaller strings into one date string and then using the datenum function:
t = datenum(strcat(C{1}(:,3),'-',C{1}(:,2),'-',C{1}(:,1)));
data = C{2};
Once you have a vector of date numbers t to go with your vector of measurements data, you can then plot them:
plot(t,data,'*'); %# Plot the points as asterisks
Now, you can change the x-axis labels to show the actual dates. One option is to use the function datetick, an easy and elegant solution given in steven's answer. Another option is to use the function datestr to create the labels yourself, then modify the XTick and XTickLabel properties of the current axes:
xpts = min(t):max(t); %# Make a full vector, filling in missing dates
set(gca,'XTick',xpts,'XTickLabel',datestr(xpts)); %# Set axes properties
NOTE: Whichever option you choose for changing the x-axis labels to date strings, you may run into trouble with the labels overlapping each other if the tick marks are too close together. You could fix this by reducing or repositioning the tick marks along the x-axis (by changing the XTick property) or by adjusting the axes FontSize property. If you wanted to rotate the labels to make them fit, you would have to erase the labels and create new rotated text objects for them. The following submission on The MathWorks File Exchange does just that:
Rotate Tick Label by Andrew Bliss
With datenum you can convert any string date into numerical format based on the date format symbols (see help datestr).
For example all this leads to the same numerical date representation:
datenum('15/05/2009 21:22','dd/mm/yyyy HH:MM');
datenum('15.05.2009 21:22','dd.mm.yyyy HH:MM');
datenum('21-22 15.05.2009','HH-MM dd.mm.yyyy');
datenum('21-22 05/15.2009','HH-MM mm/dd.yyyy');
...
The nice thing is that you can pass cell array (output from textscan) or char array directly to datenum and it will output numeric date array.
Datetick is a good option, as well as datetick2, which can be found here: MATLAB Central
Datetick2 allows panning and zooming, with adjustments to the time labels, depending on how far you're zoomed in.
I'm not sure about the dd.mm.yyyy format - you could use regexp or strrep to change the decimals to dashes if neccessary.
You can use datenum to convert the dates to a numbers, and plot the data as usual. lets say you put your dates vector in the variable called x.
Now, you can use
set(gca, 'xtick',x(1:10:end));
set(gca, 'xticklabel',datestr(x(1:10:end));
to set the ticks on the x axis.