Re: How to deal with big matrix?
- To: mathgroup at smc.vnet.net
- Subject: [mg116625] Re: How to deal with big matrix?
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Tue, 22 Feb 2011 04:42:10 -0500 (EST)
data = Table[{x[i, j], y[i, j]}, {i, 3}, {j, 4}] {{{x[1, 1], y[1, 1]}, {x[1, 2], y[1, 2]}, {x[1, 3], y[1, 3]}, {x[1, 4], y[1, 4]}}, {{x[2, 1], y[2, 1]}, {x[2, 2], y[2, 2]}, {x[2, 3], y[2, 3]}, {x[2, 4], y[2, 4]}}, {{x[3, 1], y[3, 1]}, {x[3, 2], y[3, 2]}, {x[3, 3], y[3, 3]}, {x[3, 4], y[3, 4]}}} Flatten[data[[All, All, 1]], 1] {x[1, 1], x[1, 2], x[1, 3], x[1, 4], x[2, 1], x[2, 2], x[2, 3], x[2, 4], x[3, 1], x[3, 2], x[3, 3], x[3, 4]} Flatten[data[[All, All, 2]], 1] {y[1, 1], y[1, 2], y[1, 3], y[1, 4], y[2, 1], y[2, 2], y[2, 3], y[2, 4], y[3, 1], y[3, 2], y[3, 3], y[3, 4]} Bob Hanlon ---- Szymon Roziewski <szymon.roziewski at gmail.com> wrote: ============= Hello there, I have quite big matrix with let say 1000 rows and 1100 columns. Each of element of this matrix is a point on a surface e.g. {1.232,12.123} How can I quickly get first element of each point for whole matrix and put it in a vector (1000*1100 - this will be a length of that vector) without do it in a nested loop (Do[Do[...]])? And the similar to get the second element of each point into vector. kind regards, Szymon Roziewski