CODEWITHSUNDEEP
pythonarraysmatrix
һ 刘
һ 刘

Reputation: 25

Python matrix formation

I want to write a python matrix that looks like:

[P1^3,p2^3,p3^3,p4^3 ...]
[p1^2,p2^2,p3^2,p4^2 ...]
[p1^1,p2^1,p3^1,p4^1 ...]
[p1^0,p2^0,p3^0,p4^0 ...]

The number of columns and the index of p is determined by the input i of pi

I tried many ways, but it doesn't work.

Someone please help me.

Upvotes: 0

Views: 990

Answers (2)

Warren Weckesser
Warren Weckesser

Reputation: 114781

If you really meant ** and not ^, you can do this with a single function, numpy.vander (for Vandermonde) from the numpy library (http://www.numpy.org/):

In [13]: p = numpy.array([2, 3, 5, 10])

In [14]: numpy.vander(p, 4).T
Out[14]: 
array([[   8,   27,  125, 1000],
       [   4,    9,   25,  100],
       [   2,    3,    5,   10],
       [   1,    1,    1,    1]])

The .T after the function call transposes the array, since the array created by numpy.vander is the transpose of what you want.

Upvotes: 4

fread2281
fread2281

Reputation: 1136

[[y^x for y in [p1, p2, p3, p4]] for x in [3, 2, 1, 0]] is probably what you want.

This expands to

[[y^3 for y in [p1, p2, p3, p4]], 
[y^2 for y in [p1, p2, p3, p4]],
[y^1 for y in [p1, p2, p3, p4]],
[y^0 for y in [p1, p2, p3, p4]]]

Note that ^ is xor in python.

I'm not really sure what you are trying to get here...

Also, do you mean numpy matrix/array or nested list?

Upvotes: 0

Related Questions