From: Armando Serrano Lombillo <arserlom@gm...>  20110922 12:11:46

On Wed, Sep 21, 2011 at 9:28 PM, Benjamin Root <ben.root@...> wrote: > 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 > > Ok, thanks Ben, I was thinking that maybe with some numpy array manipulation there might have been a straightforward way I wasn't seeing. Armando. 