Datenum Problem

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Lu
Lu 2011-5-15
Hi everyone!
I am loading a .txt file into matlab in the following way:
fid = fopen('data.txt');
data = textscan(fid,'%s %s %*f %*s %*f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %*[^\n]','HeaderLines',2,'Delimiter','\b\t','EndofLine','\r');
%disp(data{1});
fclose(fid);
%GET DATE AND TIME
dateandtime=data{1}(:);
%CONVERT DATETIME TO NUMERIC VALUE
datetimenumber=datenum([dateandtime{:}],'dd.mm.yy HH:MM:SS');
But when I load it like this, matlab brings the data set as cell arrays like this: EDU>> whos data Name Size Bytes Class Attributes
data 1x42 15544862 cell
So when I try to create a numeric value for the date and time (which has a format 'dd.mm.yy HH:MM:SS') matlab creates this variable:
EDU>> whos datetimenumber Name Size Bytes Class Attributes
datetimenumber 1x1 8 double
but this is wrong because my dateandtime cell array has a 31591x1 size, so the datenum should also create a 31591x1 numeric dates and times.
EDU>> whos dateandtime Name Size Bytes Class Attributes
dateandtime 31591x1 3032702 cell
I would really appreciate any hints of how can I fix this and create numeric dates and times for my dateandtime cell.
Have a nice week!
Lourdes
  2 个评论
bym
bym 2011-5-15
can you provide a few lines of data.txt?
Lu
Lu 2011-5-15
Hi proecsm,
Thank you for the reply! My data set looks a bit like this:
Hourtime Name Price1 Price2 Price3 and so on...
19.10.09 09:00:16 BASF 30 31 34
19.10.09 09:00:17 BASF 30 31 34
19.10.09 09:00:18 BASF 30 31 34
19.10.09 09:00:19 BASF 30 31 34
Is there anyway I could transform the Hourtime into numeric value? because apparently Hourtime is not loading as a string since it appears without the usual '' like '19.10.09 09:00:19'. Is there anyway i can do that because datetimenumber=datenum([dateandtime{:}],'dd.mm.yy HH:MM:SS');
is not working :(
Thank you! :)

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采纳的回答

Oleg Komarov
Oleg Komarov 2011-5-15
Your textscan is not consistent with the lines you posted:
textscan(fid,'%s %s %*f %*s %*f
For:
s s s f f f
19.10.09 09:00:16 BASF 30 31 etc...
Should be
data = textscan(fid, ['%s%s%s%*f' repmat('%f',1,n)],HeaderLines,2,'CollectOutput',1);
where n is the number of prices except the first one which is skipped.
No need to specify delimiter and line end (see default behaviour)
EDIT
Even better would be:
fmt = ['%17c%s%*f' repmat('%f',1,40) '%*[^\n]'];
opt = {'HeaderLines',2,'CollectOutput',1};
data = textscan(fid,fmt,opt{:});
dates = datenum(data{1},'dd.mm.yy HH:MM:SS')
  2 个评论
Lu
Lu 2011-5-15
Dear Oleg,
Thank you for the reply! It is true, it was not consistent because I wrote the sample data set the way I get it from matlab after doing textscan, but i was already ignoring some columns.
I have one main problem: since i want to create my time intervals, i wanted to convert the datetime column (this is the format of how it looks in my file 'dd.mm.yy HH:MM:SS') into a numeric value, but whenever I type
dateandnumber=datenum([dateandtime{:}],'dd.mm.yy HH:MM:SS');
i get just one output : 734065.375185185
and the problem is I need all the numeric values for all my dateandtime values.
Is there anything I can do to fix it?
Thank you so much! :)
Lourdes
Lu
Lu 2011-5-15
Dear Oleg,
Thank you so much!! This is really helpful and it works!!
Have a nice week!
Lourdes :)

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更多回答（1 个）

Andrei Bobrov
Andrei Bobrov 2011-5-15
so?
fid = fopen('data.txt');
t = textscan(fid,'%s','Delimiter','BASF');
fid =fclose(fid);
t = t{:};
t = reshape(strtrim(t(cellfun(@(x)~isempty(x),t)))',2,[])';
out = [datenum(t(:,1),'dd.mm.yy HH:MM:SS') str2num(char(t(:,2)))]
  1 个评论
Lu
Lu 2011-5-15
Dear Andrei,
Thank you for the help! I don´t entirely get your code but I guess it is trying to eliminate empty spaces? but I don´t have empty spaces in my data set. Could you please explain me a bit more the last two lines of code please? I would really appreciate it :)
Thank you,
Lourdes

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