On 28/03/14 09:42, Jose Amoreira wrote: > Hello! > Here is something that surprised me and I still didn't get it. > > If we want to store a matrix in pure python (no numpy), the first thing > that comes to (my) mind is to use a list of lists, like the list l below: > In [1]: l=[ > ...: [11,12,13], > ...: [21,22,23] > ...: ] > > We can access individual components of this object in a simple, to be > expected way: > > In [2]: l[0][1], l[1][0] > Out[2]: (12, 21) > > OK, that's fine. If we want to access individual rows of this matrix > like object, the standard slice notation (on the second index) works as > expected also: > > In [3]: l[0][:] > Out[3]: [11, 12, 13] > > In [4]: l[1][:] > Out[4]: [21, 22, 23] > > Again, fine! But what if we want to access a particular row? My first > guess was that standard slice notation on the first index would do it, > but it doesn't! Instead, we get the rows again: > > In [6]: l[:][0] > Out[6]: [11, 12, 13] > > In [7]: l[:][1] > Out[7]: [21, 22, 23] >
Jose, Just for clarity, are you trying to access a particular *column* in your last example? Bob -- Bob Williams System: Linux 3.11.10-7-desktop Distro: openSUSE 13.1 (x86_64) with KDE Development Platform: 4.12.3 Uptime: 06:00am up 4 days 19:51, 4 users, load average: 0.37, 0.18, 0.15 _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
