Octave 4.0 Help requested and / or possible bug?

[jmb]

Hello,

I am trying to import some data which contains date & time strings for
the first time in octave 4.0.0 (Ubuntu12.04 64bit).  I have tried
various methods but have not succeeded.

What I really want to do is plot segments of the 1757 data points, in
such as way that all plots begin at the same origin even though the time
stamped data runs into several days.

If I plot all 1757 points it may look something like this:

|
|
|   .....         '''
|   .   .        '   '
|   .    .      '     '
|  .      ......'      '''' (2 successive waves)
+--------------------------------------------

But I want to do this:

|
|
|   .'''
|   .   '
|   .    '
|  .'     ''''... (i.e both waves starting at the same time)
+--------------------------------------------

(I am unable to place two symbols in the same location. Also if the
above representations look mangled please try using a fixed width font)

Could somebody take a look at the following code and provide some
assistance as to how I can accomplish what I am attempting to do with
Date_Time & Data{2}, please?

The 3 problems I am facing are:
a) Plotting just Num & Data{2} works
b) Converting Data{1} so that I can use it in a plot does not work.  Is
this a bug as related to the URL at the end?
c) Attempts at plotting overlapping segments using Num & Data{2}, I do
not know how to do that.

Thank you.

Regards, JMB


#!/usr/bin/octave

# Testing... some code:
Data_Test = ['06/01/2015 3:07:12';'06/01/2015 3:07:23']
datevec(Data_Test,'mm/dd/yyyy HH:MM:SS')     # Works
whos Data_Test
%Variables in the current scope:
%
%   Attr Name           Size                     Bytes  Class
%   ==== ====           ====                     =====  =====
%        Data_Test      2x18                        36  char
%
%Total is 36 elements using 36 bytes

# This the format of the input file 'GTA.csv'
# with 7 comment lines and 2 lines of data

% Comment Line 1
% Comment Line 2
% Comment Line 3
% Comment Line 4
% Comment Line 5
% Comment Line 6
% Comment Line 7
%"10/03/2016 10:13:22"        94.7        372        0.00        120.2
     0.0        0.01        12.5        0.1        12.6        0.01
  25.6        91.4        90.5        90.3        90.0        90.6
%"10/03/2016 10:14:22"        94.7        372        0.00        120.1
     0.0        0.00        12.5        0.0        12.7        0.01
  25.6        91.8        90.1        89.8        90.3        90.5
% Multiple similar lines have been deleted for brevity

fileID = fopen('GTA.csv');
Data = textscan(fileID,'%s %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f
%f','Delimiter','\t','headerLines', 7);
fclose(fileID);

# whos Data
%Variables in the current scope:
%
%   Attr Name        Size                     Bytes  Class
%   ==== ====        ====                     =====  =====
%        Data        1x17                    261793  cell
%
%Total is 17 elements using 261793 bytes

formatIn = 'mm/dd/yyyy HH:MM:SS';

# figure('Position',[0,0,1000,1000])
figure(1);
Num = 1:length(Data{2})
1 = plot(Num,Data{2},'b');                   # Works
# h1 = plot(Date_Time,Data{2},'b');
datetick (formatIn);

# Date_Time = arrayfun(@datevec, [Data{1}; formatIn])   # error:
datevec: none of the standard formats match the DATE string

whos Data
%Variables in the current scope:
%
%   Attr Name        Size                     Bytes  Class
%   ==== ====        ====                     =====  =====
%        Data        1x17                    261793  cell
%
%Total is 17 elements using 261793 bytes

whos Data{2}
%Variables in the current scope:
%
%   Attr Name         Size                     Bytes  Class
%   ==== ====         ====                     =====  =====
%        Data{2}   1757x1                      14056  double
%
%Total is 1757 elements using 14056 bytes


# Ref:
https://stackoverflow.com/questions/31347193/trouble-with-datenum-in-octave