I want to ask a simple question about datatime format in matlab.
I know "HH:MM:SS:SSS"is like "Hour:Minute:Second:MillisSecond".What if I just need "MM:SS:SSS". Is this possible in matlab?
Can I use the following code in my program?
dt = datestr(A,'MM:SS:SSS')
Thanks.
What I am trying to do is add a timestamp at each line of my output txt.
The first line is "00：00：000"
The second line is "00：00：100"
Correct me if i'm wrong, but there's no SSSS for MillisSecond with datetime format in Matlab. You should read more carefully here.
In case you need MillisSecond, you have to use FFF, and you can only get MillisSecond in 3 digits:
datestr(rem(now, 1), 'MM:SS:FFF');
Related
I've looked for help on the internet for the following, but I could not find a satisfying answer: for an assignment, I need to plot the time series of a certain variable (the term spread in percentages), with years on the x-axis.
However, we use daily data. Does anybody know a convenient way in which this can be done? The 'date' variable that I've got is formulated in the following way: 20111017 represents the 17th of October 2011.
I tried to extract the first 4 numbers of the variable 'date', by using the substr(date, 1, 4) command, but the message 'type mismatch' popped up. Also, I'm not quite sure if it gives the right information if I only use the years to plot daily data (over the years). It now gives the following graph, which doesn't look that nice.
Answering the question in your title.
The date() function expects a string. If your variable with value 20111017 is in a numeric format you can convert it like this: tostring datenum , gen(datestr).
Then when using the date() function you must provide a mask that tells Stata what format the date string is in. Below is a reproducible example you can run to see how this works.
* Example generated by -dataex-. For more info, type help dataex
clear
input float datenum
20111016
end
* Convert numberic varaible to string
tostring datenum , gen(datestr)
* Convert string to date
gen date = date(datestr, "YMD")
* Display date as date
format date %td
If this does not help you, try to provide a reproducible example.
This adds some details to the helpful answer by #TheIceBear.
As he indicates, one way to get a Stata daily date from your run-together date variable is convert it to a string first. But tostring is just one way to do that and not essential. (I have nothing against tostring, as its original author, but it is better suited to other tasks.)
Here I use daily() not date(): the results are identical, but it's a good idea to use daily(): date() is all too often misunderstood as a generic date function, whereas all it does is produce daily dates (or missings).
To get a numeric year variable, just divide by 10000 and round down. You could convert to a string, extract the first 4 characters, and then convert to numeric, but that's more operations.
clear
set obs 1
gen long date = 20111017
format date %8.0f
gen ddate = daily(strofreal(date, "%8.0f"), "YMD")
format %td ddate
gen year = floor(date/10000)
list
+-----------------------------+
| date ddate year |
|-----------------------------|
1. | 20111017 17oct2011 2011 |
+-----------------------------+
I have a .csv file with the first column containing dates, a snippet of which looks like the following:
date,values
03/11/2020,1
03/12/2020,2
3/14/20,3
3/15/20,4
3/16/20,5
04/01/2020,6
I would like to import this data into Matlab (I think the best way would probably be using the readtable() function, see here). My goal is to bring the dates into Matlab as a datetime array. As you can see above, the problem is that the dates in the original .csv file are not consistently formatted. Some of them are in the format mm/dd/yyyy and some of them are mm/dd/yy.
Simply calling data = readtable('myfile.csv') on the .csv file results in the following, which is not correct:
'03/11/2020' 1
'03/12/2020' 2
'03/14/0020' 3
'03/15/0020' 4
'03/16/0020' 5
'04/01/2020' 6
Does anyone know a way to automatically account for this type of data in the import?
Thank you!
My version: Matlab R2017a
EDIT ---------------------------------------
Following the suggestion of Max, I have tried specifiying some of the input options for the read command using the following:
T = readtable('example.csv',...
'Format','%{dd/MM/yyyy}D %d',...
'Delimiter', ',',...
'HeaderLines', 0,...
'ReadVariableNames', true)
which results in:
date values
__________ ______
03/11/2020 1
03/12/2020 2
NaT 3
NaT 4
NaT 5
04/01/2020 6
and you can see that this is not working either.
If you are sure all the dates involved do not go back more than 100 years, you can easily apply the pivot method which was in use in the last century (before th 2K bug warned the world of the danger of the method).
They used to code dates in 2 digits only, knowing that 87 actually meant 1987. A user (or a computer) would add the missing years automatically.
In your case, you can read the full table, parse the dates, then it is easy to detect which dates are inconsistent. Identify them, correct them, and you are good to go.
With your example:
a = readtable(tfile) ; % read the file
dates = datetime(a.date) ; % extract first column and convert to [datetime]
idx2change = dates.Year < 2000 ; % Find which dates where on short format
dates.Year(idx2change) = dates.Year(idx2change) + 2000 ; % Correct truncated years
a.date = dates % reinject corrected [datetime] array into the table
yields:
a =
date values
___________ ______
11-Mar-2020 1
12-Mar-2020 2
14-Mar-2020 3
15-Mar-2020 4
16-Mar-2020 5
01-Apr-2020 6
Instead of specifying the format explicitly (as I also suggested before), one should use the delimiterImportoptions and in the case of a csv-file, use the delimitedTextImportOptions
opts = delimitedTextImportOptions('NumVariables',2,...% how many variables per row?
'VariableNamesLine',1,... % is there a header? If yes, in which line are the variable names?
'DataLines',2,... % in which line does the actual data starts?
'VariableTypes',{'datetime','double'})% as what data types should the variables be read
readtable('myfile.csv',opts)
because the neat little feature recognizes the format of the datetime automatically, as it knows that it must be a datetime-object =)
I got one problem with UNIX time to human readable time. In fact I was also thinking is it possible to conterte UNIX time to Comma-separated-values...so that I can make a plot based on this converted real time and the corresponding values.
But my UNIX is in int64 format, I tried using
unix_epoch = datenum(1970,1,1,0,0,0);
for i=1:1:size(data_mat)
matlab_time(i,1) = data_mat(i,1)./86400 + unix_epoch;
end
for example: 1352434077. So when I tried to converte it with this code: It gave 735087..not something like YYYY-MM-DD: hh:mm:ss ...can anyone gave me a hint? Thanks a lot!
You need to use datestr (the output of which is a string):
>> time_num = 735087
time_num = 735087
>> datestr(time_num)
ans = 06-Aug-2012
You can also specify a format for the output, such as 'dd-mmm-yyyy HH:MM:SS', check the doc.
At the moment I am using xlsread to open a set of data that I have in excel with given timestamps. But when these values are placed in matlab it changes the formatting of the timestamp.
In excel it is:
dd/mm/yyyy HH:MM
but when it puts it into matlab it changes it to
mm/dd/yyyy HH:MM
which ruins my other code. I have tried using formatIn and specifying it, but then it returns an error if no value for midnight is given.
Any help would be appreciated.
You can use datenum and datestr to convert the format to what you want. In the following example I'm assuming your timestamps are contained in a cell array of strings, but it also works if it's a char matrix:
>> timestamps = {'08/25/2014 13:14'; '08/26/2014 14:15'} %// mm/dd/yyyy HH:MM
>> result = datestr(datenum(timestamps, 'mm/dd/yyyy HH:MM'), 'dd/mm/yyyy HH:MM')
result =
25/08/2014 13:14
26/08/2014 14:15
What Luis recommended should help you to get any format that you like. However there is something important to realize here:
Excel does not 'have' the date in your format. It has the date stored as a number like 123546.123 and presents it to you in a certain way.
If you want to get the date in exactly the way that excel presents it, the trick is to avoid importing the relevant column as a date, but just import it as text instead.
How to do this depends on your import method, but it should not be very hard.
I am trying to export a double array from MATLAB into a txt file. I can do this easily but the data is not structured how i need it. I need the data to be structured in the following way in the txt file;
-0.0195
-0.0217
-0.0260
-0.0274
-0.0258
-0.0246
-0.0244
-0.0233
-0.0209
-0.0221
Does anyone know how this would be done using dlmwrite?
Maybe something like this?
A=[-0.0195; -0.0217; -0.0260; -0.0274; -0.0258; -0.0246; -0.0244; -0.0233; -0.020;-0.0221];
dlmwrite('example.txt', A, 'newline', 'pc')
The last two argument determines the new line character used (CR or CR+LF), depending on the platform. Use 'pc' for the Windows version, and 'unix' for all others.
For full cross-platformness, you can use the isunix function, and have something like the following preceding your code:
if isunix==true
platform='unix'
else
platform='pc'
end
and then use the platform variable as the last argument in dlmwrite.
If your data is in a row-vector called A this will write it into a column in afile.txt:
dlmwrite('afile.txt',A,'\n')