On Tuesday, December 13, 2016 at 12:45:49 PM UTC+3:30, Peter Otten wrote: > Elnaz wrote: > > > hi > > i am begginer in python. I have written a code and given this error: > > IndexError: list index out of range > > > > In my program, I have h=32 bits input. i divide this 32 bits to 4*8 block > > and every 8-block is n. so n=0:7;(h=int(n/4)) I want to rotate 0 to 7 bits > > for 2 bits: 0,1,2,3,4,5,6,7--->2,3,4,5,6,7 Iwrite this code: > > def rottwo(self, X, n, r): > > assert r >= 1 > > temp = [None]*n > > for i in range(n-r) : > > temp[i] = X[i+r] > > for i in range(n-r,n) : > > temp[i] = X[i-n+r] > > return temp > > this function work correctly. but I also want to rotate 24 to 31 bits for > > 5 bits: 24,25,26,27,28,29,30,31-->29,30,31,24,25,26,27,28 > > > > when I write this code: > > def rotfive(self, X, n, r): > > assert r >= 1 > > temp = [None]*n > > for i in range(n-r) : > > temp[i+24] = X[i+3*n+r] > > for i in range(n-r,n) : > > temp[i+24] = X[i+2*n+r] > > return temp > > beacase temp is of size n I cannot access index 3*n+i. index on the list > > temp should be less than equal to n-1 . I son't know how I must correct > > this!!!!!!!! Is there any one to help me? > > thanks in advanse. > > I think you are making this harder than necessary. Python slices make > accessing parts of a list quite elegant: > > >>> items > [0, 10, 20, 30, 40, 50, 60, 70, 80, 90] > >>> items[2:5] > [20, 30, 40] > >>> items[3:] > [30, 40, 50, 60, 70, 80, 90] > > You can use this to implement a function that creates a rotated list with an > arbitrary offset: > > >>> def rot(items, offset): > ... return items[offset:] + items[:offset] > ... > >>> rot(items, 2) > [20, 30, 40, 50, 60, 70, 80, 90, 0, 10] > >>> rot(items, 7) > [70, 80, 90, 0, 10, 20, 30, 40, 50, 60] > >>> rot(items, -2) > [80, 90, 0, 10, 20, 30, 40, 50, 60, 70] > > To rotate part of a list extract that part using slice notation, rotate it > and write it back: > > >>> def rot_part(items, offset, start, stop): > ... items = list(items) > ... items[start:stop] = rot(items[start:stop], offset) > ... return items > ... > >>> rot_part(range(32), 5, 24, 32) > [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, > 21, 22, 23, 29, 30, 31, 24, 25, 26, 27, 28] > > If you pass a list as the first argument > > items = list(items) > > makes of copy of the list, but it will also convert an arbitrary iterable to > a list. That's why I can pass the range object.
i really appreciate your help. it works. -- https://mail.python.org/mailman/listinfo/python-list