using datenum results in not showing both strings

Question

1. How do I read in this data properly so that the date parses properly? I am trying to concatenate strings I read from a file but the output I get is mixed up. The output is the x axis.Also, the spacing from x axis has numbers instead of the string I want. The file has 4 columns,date,time,temperature and value. The date is "01.01.2013 " and the time "09:08:02"

Also, if I want to use only first column (with date) how can I do this? Because using datenum(mydata{1}) results to "Cannot parse date 01.01.2013"

...
mydata = textscan(fid, '%s %s %f %f', 'delimiter',';', 'HeaderLines',1);
date={};
temp={};
..
date{1}=datenum( strcat(mydata{1},{' '},mydata{2}) );
...

2. How do I correct the axis ticks?

I am then trying to plot data using plotyy and want the x-axis to be the date, but I am getting two different axis labels.

Here is the code I am using:

temp = mydata{4};
plotyy(date,temp,date,2*temp);
datetick('x','mmm.dd,yyyy');

Here is the resulting image:

enter image description here

---------------UPDATE---------------------------------------

Here is the code:

fid = fopen('test2.txt','r');
mydata = textscan(fid, '%s %s %f %f', 'delimiter',';', 'HeaderLines',1);
fclose(fid);

date=datenum( strcat(mydata{1},{' '},mydata{2}),'mmm.dd,yyyy HH:MM:SS' );
temperature=mydata{3};
value=mydata{4};


[AX,H1,H2]=plotyy(date,temperature,date,value,'plot'); 
set(get(AX(1),'Ylabel'),'String','Temperatures');
set(get(AX(2),'Ylabel'),'String','Value');



set(H1,'LineStyle','--');
set(H2,'LineStyle',':');
datetick(AX(1),'x','mmm.dd,yyyy');


title('Temperatures - Values');
xlabel('Date')

and the file

Date;Time;Temp;value
Jan.01,2013; 11:00:00;20;10                         
Feb.08,2013; 12:00:00;23;11
Mar.04,2013; 04:02:00;24;15
Apr.10,2013; 08:04:00;28;20
May.10,2013; 12:05:00;32;30
Jun.04,2013; 10:06:0;33;27

klurie klurie · Accepted Answer · 2013-03-31T22:12:38

1. Parsing input

You are receiving the "cannot parse" error, because you are also not including a format string (formatIn). See the documentation for datenum.

If you want to convert only the first column to the date, this would look like:

date=datenum(mydata{1},'mm.dd.yyyy');

If you want to convert both the first and second columns, try:

 date=datenum( strcat(mydata{1},{' '},mydata{2}),'mm.dd.yyyy HH:MM:SS');

Here is the entire code I am running, which seems to work. Note that there is no header row in my datafile.

% data.txt
% 01.01,2013; 11:00:47;10;20
% 01.02,2013; 11:00:57;10;40

fid = fopen('data.txt');
mydata = textscan(fid, '%s %s %f %f', 'delimiter',';');
date=datenum( strcat(mydata{1},{' '},mydata{2}),'mm.dd,yyyy HH:MM:SS');

2. Getting correct plots

There are two different x-ticks for plotyy command. By setting datetick in the way you did, you are only changing one of them. Instead, change first x-tick to date tick and set the second x-ticks to empty.

temp = mydata{4};
[AX,H1,H2] = plotyy(date,temp,date,2*temp);
datetick(AX(1),'x','mmm.dd,yyyy');
set(AX(2),'XTick',[])

using datenum results in not showing both strings

1 Answers