From: Benjamin Root <ben.root@ou...>  20110921 19:28:53

On Wed, Sep 21, 2011 at 2:00 PM, Armando Serrano Lombillo < arserlom@...> wrote: > Hello I have a dat set like this one > a=[[x1, y1, cat1], [x2, y2, cat1], ..., [x8, y8, cat1], [x9, y9, cat2], > ..., [x34, y34, cat2], [x35, y35, cat3],...] > and I don't know beforehand how many diffferent categories there will be or > how long they will be. > > I would like to make a plot like this: > ax.plot(a[0:i1, 0], a[0:i1, 1], label=cat1) > ax.plot(a[i1:i2, 0], a[i1:i2, 1], label=cat2) > ax.plot(a[i2:i3, 0], a[i2:i3, 1], label=cat3) > ... > > where i1, i2... are the indices where the data set changes fomt cat1 to > cat2, cat2 to cat3... > > Does anybody see an easy way of coding this? > > Thanks, > Armando. > Maybe something like this? (Warning: untested!) from collections import OrderedDict b = OrderedDict() for index, coords in enumerate(a) : b[coords[2]] = index + 1 a = np.array([[c[0], c[1]] for c in a]) prevIndex = 0 for cat, curIndex in b.iteritems() : ax.plot(a[prevIndex:curIndex, 0], a[prevIndex:curIndex, 1], label=cat) prevIndex = curIndex The ordered dictionary may or may not be available in whatever version of python you use, but it guarantees the order. I hope that helps! Ben Root 