Re: problem reading file with time-stamps

[Ben Abbott]

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