rotate points and draw plot

rotate and draw plot.py

import matplotlib.pyplot as plt
import csv
import math
def rotate_vector(v, angle, anchor):
    """Rotate a vector `v` by the given angle, relative to the anchor point."""
    x, y = v

    x = float(x) - anchor[0]
    y = float(y) - anchor[1]
    # Here is a compiler optimization; inplace operators are slower than
    # non-inplace operators like above. This function gets used a lot, so
    # performance is critical.

    cos_theta = math.cos(math.radians(angle))
    sin_theta = math.sin(math.radians(angle))

    nx = x*cos_theta - y*sin_theta
    ny = x*sin_theta + y*cos_theta

    nx = nx + anchor[0]
    ny = ny + anchor[1]
    return [nx, ny]

x=[]
z=[]
x_rotate=[]
z_rotate=[]   

f= open("data.csv")
#append values to list
for row in csv.reader(f):
    x.append(row[0])
    z.append(row[1])
    x_rotate.append(rotate_vector((row[0],row[1]),8,(0,0))[0])
    # rotate x to 8 angle 
    z_rotate.append(rotate_vector((row[0],row[1]),8,(0,0))[1])
    # rotate z to 8 angle 
plt.plot(x, z, 'r.')
plt.plot(x_rotate, z_rotate, 'r.')

plt.axis([-1, 30, -5,2])
plt.show()