BUG on plotting.py radviz

[mtinti]

pandas 0.14.0 in plotting.py

the varable n in line 389: n = len(frame)
is wrongly asigned again in line 404: n = len(frame.columns) - 1
that brakes in line 409: for i in range(n):

This shuld fix the bug
line 389: rows = len(frame)
line 409: for i in range(rows):

[jreback]

this was fixed by #8199 already

thanks for the report