On Dec 26, 11:28 am, Lie Ryan <lie.1...@gmail.com> wrote: > On 12/26/2011 05:27 AM, Yigit Turgut wrote: > > > > > > > > > > > On Dec 25, 7:06 pm, Rick Johnson<rantingrickjohn...@gmail.com> wrote: > >> On Dec 25, 9:33 am, Yigit Turgut<y.tur...@gmail.com> wrote: > >>> Hi all, > > >>> I have a text file as following; > > >>> 0.200047 0.000000 > >>> 0.200053 0.160000 > >>> 0.200059 0.000000 > >>> 0.200065 0.080000 > >>> 0.200072 0.000000 > >>> 0.200078 0.160000 > > >>> And I am trying to plot it with ; > > >>> filenames = sys.argv[1:] > >>> if len(filenames) == 0: > >>> filenames = [sys.stdin] > >>> for filename in filenames: > >>> t,y1 = numpy.genfromtxt(filename, unpack=True) > >>> pyplot.plot(t,y1) > >>> pyplot.show() > > >>> But graph seems weird, not as it supposed to be. Any ideas ? > > >> Interesting. Of course "weird" leaves a LOT to be desired. On a scale > >> of 1-10, how "weird" is the result? > > > I apply a 1Khz test signal just to see if things run smoothly, but I > > see spikes at lower and higher ends (logic 0,1) where I should see a > > clean rectangle pwm signal. By the look of it I say weirdness is > > around 3/10. > > What are you expecting? Your data produces something that looks like the > plot on the right of this screenshot > (http://i44.tinypic.com/wwhlvp.jpg), I don't see anything weird with > that; if you are expecting a square-wave-like plot (like on the left), > then you should use a square-wave-like data, pyplot wouldn't magically > transform a spiked-plot to squared-plot. > > Here's what I use to convert the data on right plot to data on left > plot, I don't know much about numpy so it might be possible to do it > more efficiently or numpy might even have something like it already. > > from itertools import izip_longest > def to_square(t, y1): > sq_data = [[], []] > for x,y, xn in izip_longest(data[0], data[1], data[0][1:]): > sq_data[0].append(x) > sq_data[1].append(y) > sq_data[0].append(xn) > sq_data[1].append(y) > return numpy.array(sq_data, dtype=float)
Thanks for the tip. I know that I feed a square wave signal and record this data. Thus I believe the situation can be related to sampling frequency. Couldn't get your code working, maybe because I import the data from file. -- http://mail.python.org/mailman/listinfo/python-list