Re: problem reading file with time-stamps

[Ben Abbott]

On Dec 13, 2011, at 9:28 AM, BVBA NuKey Music wrote:

> 2011/12/13 Ben Abbott <address@hidden>
> 
>> On Dec 13, 2011, at 8:24 AM, BVBA NuKey Music wrote:
>> 
>> > 2011/12/13 Ben Abbott <address@hidden>
>> >>
>> >> On Dec 13, 2011, at 7:39 AM, BVBA NuKey Music wrote:
>> >>
>> >> > 2011/12/13 Joanna Cheng <address@hidden>
>> >> >> On Tue, Dec 13, 2011 at 7:51 PM, BVBA NuKey Music <address@hidden> 
>> >> >> wrote:
>> >> >> > I'm trying to read a file with four columns which has timestamps in 
>> >> >> > the
>> >> >> > first column:
>> >> >> >
>> >> >> > The data is available in the file in the following format:
>> >> >> > Dec-13-09:46:45 21.4 +4.76442190E-01 8.135530E-06 1.553691E+00
>> >> >> > Dec-13-09:47:12 21.4 +4.76439120E-01 8.135839E-06 1.553726E+00
>> >> >> > Dec-13-09:47:39 21.4 +4.76427260E-01 8.136261E-06 1.553853E+00
>> >> >> >
>> >> >> > first field is a timestamp then a space followed by a temperature 
>> >> >> > then a
>> >> >> > space ...
>> >> >> >
>> >> >> > As you can see here below, octave doesn't accept the file because of 
>> >> >> > the
>> >> >> > timestamps,
>> >> >> > can anyone here help me solve this problem?
>> >> >> >
>> >> >> > octave:1> y=load('x7r0.7vac0vdc.dat');
>> >> >> > error: load: failed to read matrix from file `x7r0.7vac0vdc.dat'
>> >> >> > error: evaluating assignment expression near line 1, column 2
>> >> >>
>> >> >>
>> >> >> I actually wrote a bit of code to do this with csv files. See here:
>> >> >> http://www.octave.org/wiki/index.php?title=Tips_and_tricks#Load_Comma_Separated_Values_.28.2A.csv.29_files
>> >> >>
>> >> >> Sample output as below:
>> >> >>
>> >> >> octave:19> A=textread("timestamps.txt", "%d", "delimiter", " ");
>> >> >> octave:20> B=textread("timestamps.txt", "%s", "delimiter", " ");
>> >> >> octave:21> inds = isnan(A);
>> >> >> octave:22> B(!inds) = num2cell(A(!inds));
>> >> >> octave:23> B
>> >> >> B =
>> >> >> {
>> >> >>  [1,1] = Dec-13-09:46:45
>> >> >>  [2,1] =  21.400
>> >> >>  [3,1] =  0.47644
>> >> >>  [4,1] = 8.1355e-006
>> >> >>  [5,1] =  1.5537
>> >> >>  [6,1] = Dec-13-09:47:12
>> >> >>  [7,1] =  21.400
>> >> >>  [8,1] =  0.47644
>> >> >>  [9,1] = 8.1358e-006
>> >> >>  [10,1] =  1.5537
>> >> >>  [11,1] = Dec-13-09:47:39
>> >> >>  [12,1] =  21.400
>> >> >>  [13,1] =  0.47643
>> >> >>  [14,1] = 8.1363e-006
>> >> >>  [15,1] =  1.5539
>> >> >> }
>> >> >> octave:24> class(B)
>> >> >> ans = cell
>> >> >> octave:25> class(B{1})
>> >> >> ans = char
>> >> >> octave:26> class(B{2})
>> >> >> ans = double
>> >> >>
>> >> >> Hope that helps,
>> >> >> Joanna
>> >> >
>> >> > Thanks for replying but if I try out your code I get the following 
>> >> > errors:
>> >> > octave:3> A=textread("timestamps.txt", "%d", "delimiter", " ")
>> >> > error: `textread' undefined near line 3 column 3
>> >> > error: evaluating assignment expression near line 3, column 2
>> >> >
>> >> > and
>> >> >
>> >> > octave:3> B=textread("timestamps.txt", "%s", "delimiter", " ");
>> >> > error: `textread' undefined near line 3 column 3
>> >> > error: evaluating assignment expression near line 3, column 2
>> >> >
>> >> > Any idea what is going wrong?
>> >> >
>> >> > thanks in advance
>> >> > nukey
>> >>
>> >> (please reply below so that others arriving late can more easilly follow 
>> >> along)
>> >>
>> >> I suspect you are using Octave 3.2 ? correct?
>> >>
>> >> Joanna is likely using Octave 3.4.x or the developers sources (3.6.x).
>> >>
>> >> If you are unable to upgrade your version of Octave, can you install the 
>> >> io package? You'll want to be sure that the version is < 1.0.13. The 
>> >> versions more recent that this do not include the textread() function (it 
>> >> was moved to Octave's core).
>> >>
>> >> Ben
>> >
>> > OK, I installed octave-io but I'm still facing problems:
>> > octave:5> A=textread("timestamps.txt", "%d", "delimiter", " ");
>> > error: Unknown property delimiter.
>> > error: Invalid argument specified
>> >
>> > So I removed the word "delimiter" which gave me:
>> > octave:7> A=textread("timestamps.txt", "%d", " ")
>> > A =
>> >
>> >    3.6074e-313
>> >    3.6074e-313
>> >    3.6074e-313
>> >
>> > octave:8> A=textread("timestamps.txt", "%s", " ")
>> > A =
>> >
>> > {
>> >   [1,1] = Dec-13-09:46:45
>> >   [2,1] = Dec-13-09:47:12
>> >   [3,1] = Dec-13-09:47:39
>> > }
>> >
>> >
>> > But how can I get my data in a matrix?
>> >
>> > thanks in advance
>> > nukey
>> >
>> 
>> *** please reply below so that those arriving late can follow along ***
>> 
>> This version of textread() may not support the "delimiter" option. However, 
>> whitespace is treated as a delimiter by default, so you don't need to 
>> specify it.
>> 
>> The data as a string followed by 4 floats (correct?). So the commands below 
>> should work.
>> 
>>        fmt = "%s %f %f %f %f";
>>        [A, B, C, D, E] = textread ("timestamp.txt", fmt);
>> 
>> Ben
> 
> Wow, that works great, is there a way to achieve the following too?
> y=[A B C D E]
> I noticed that y=[B C D E] works but I can't add the first column, probably 
> because it is of a different data-type
> 

*** please reply below so that those arriving late can follow along ***

Since you are mixing character data with doubles, you'll need to use a cell 
array for that.

        y = {A, B, C, D, E};

Ben