remove randomly chosen elements from array

How can I do the following in Python?

• begin with ordered array, x
• randomly sort array elements, according to some probability function
• take first N random elements
• remove chosen elements from original ordered array
• caveat: in the actual problem, I'd like to eliminate the indices corresponding to N elements, not just the values, as x may have repeated values. Example: the variable x from [x,y] = np.meshgrid(xrange,yrange) may have repeated values, but the indices imply a corresponding y-value, which is important.

My code thusfar:

import numpy as np

N = 5;
x = np.linspace(0,5,11)
pdf = np.exp(-x**2);
pdf = pdf/np.sum(pdf);

x_rand_sorted = np.random.choice(x,N,replace=False,p = pdf)

print 'x:',x
print 'first N random elements:', x_rand_sorted
print 'x without random elements = ??'