# -*- coding: utf-8 -*-
"""Create simple LLG Files which describe magnetization in 2D (z-Dim=1)."""
import numpy as np
import matplotlib.pyplot as plt
from numpy import pi
def slab(dim, params):
'''Get the magnetic shape of a slab.
Arguments:
dim - the dimensions of the grid, shape(y, x)
center - center of the slab in pixel coordinates, shape(y, x)
width - width of the slab in pixel coordinates, shape(y, x)
Returns:
the magnetic shape as a 2D-boolean-array.
'''
center, width = params
shape_mag = np.array([[abs(x - center[1]) <= width[1] / 2
and abs(y - center[0]) <= width[0] / 2
for x in range(dim[1])] for y in range(dim[0])])
return shape_mag
def disc(dim, params):
'''Get the magnetic shape of a disc.
Arguments:
dim - the dimensions of the grid, shape(y, x)
center - center of the disc in pixel coordinates, shape(y, x)
radius - radius of the disc in pixel coordinates, shape(y, x)
Returns:
the magnetic shape as a 2D-boolean-array.
'''
center, radius = params
shape_mag = np.array([[(np.hypot(x-center[1], y-center[0]) <= radius)
for x in range(dim[1])] for y in range(dim[0])])
return shape_mag
def filament(dim, params):
'''Get the magnetic shape of a single filament in x or y direction.
Arguments:
dim - the dimensions of the grid, shape(y, x)
pos - position of the filament (pixel coordinate)
x_or_y - string that determines the orientation of the filament
('y' or 'x')
Returns:
the magnetic shape as a 2D-boolean-array.
'''
pos, x_or_y = params
shape_mag = np.zeros(dim)
if x_or_y == 'y':
shape_mag[:, pos] = 1
else:
shape_mag[pos, :] = 1
return shape_mag
def alternating_filaments(dim, params):
'''Get the magnetic shape of alternating filaments in x or y direction.
Arguments:
dim - the dimensions of the grid, shape(y, x)
spacing - the distance between two filaments (pixel coordinate)
x_or_y - string that determines the orientation of the filament
('y' or 'x')
Returns:
the magnetic shape as a 2D-boolean-array.
'''
spacing, x_or_y = params
shape_mag = np.zeros(dim)
if x_or_y == 'y':
# TODO: List comprehension:
for i in range(0, dim[1], spacing):
shape_mag[:, i] = 1 - 2 * (int(i / spacing) % 2) # 1 or -1
else:
for i in range(0, dim[0], spacing):
shape_mag[i, :] = 1 - 2 * (int(i / spacing) % 2) # 1 or -1
return shape_mag
def single_pixel(dim, params):
'''Get the magnetic shape of a single magnetized pixel.
Arguments:
dim - the dimensions of the grid, shape(y, x)
pixel - the coordinates of the magnetized pixel, shape(y, x)
Returns:
the magnetic shape as a 2D-boolean-array.
'''
pixel = params
shape_mag = np.zeros(dim)
shape_mag[pixel[0], pixel[1]] = 1
return shape_mag
def create_hom_mag(dim, res, beta, shape_fun, params,
filename='output.txt', plot_mag_distr=False):
'''Create homog. magnetization data, saved in a file with LLG-format.
Arguments:
dim - the dimensions of the grid, shape(y, x)
res - the resolution of the grid
(real space distance between two points)
beta - the angle of the magnetization
filename - the name of the file in which to save the data
shape_fun - the function to determine the shape of the magnetization,
several are defined in this module
params - a tuple of parameters used in shape_fun
Returns:
the the magnetic shape as a 2D-boolean-array.
'''
res *= 1.0E-9 / 1.0E-2 # from nm to cm
x = np.linspace(res / 2, dim[1] * res - res / 2, num=dim[1])
y = np.linspace(res / 2, dim[0] * res - res / 2, num=dim[0])
xx, yy = np.meshgrid(x, y)
shape_mag = shape_fun(dim, params)
x_mag = np.array(np.ones(dim)) * np.cos(beta) * shape_mag
y_mag = np.array(np.ones(dim)) * np.sin(beta) * shape_mag
z_mag = np.array(np.zeros(dim))
if (plot_mag_distr):
fig = plt.figure()
fig.add_subplot(111, aspect='equal')
plt.quiver(x_mag, y_mag, pivot='middle', angles='xy', scale_units='xy',
scale=1, headwidth=6, headlength=7)
xx = np.reshape(xx,(-1))
yy = np.reshape(yy,(-1))
zz = np.array(np.ones(dim[0] * dim[1]) * res / 2)
x_mag = np.reshape(x_mag,(-1))
y_mag = np.reshape(y_mag,(-1))
z_mag = np.array(np.zeros(dim[0] * dim[1]))
data = np.array([xx, yy, zz, x_mag, y_mag, z_mag]).T
with open(filename,'w') as mag_file:
mag_file.write('LLGFileCreator2D: %s\n' % filename.replace('.txt', ''))
mag_file.write(' %d %d %d\n' % (dim[1], dim[0], 1))
mag_file.writelines('\n'.join(' '.join('{:7.6e}'.format(cell)
for cell in row) for row in data) )
def create_logo(edge, res, beta = pi/2, filename='logo.txt', plot_mag_distr=False):
# TODO: rewrite so that every possible shape_mag can be given as argument
# TODO: write a script for creating, displaying and saving the logo
dim = (edge, edge)
res *= 1.0E-9 / 1.0E-2 # from nm to cm
x = np.linspace(res / 2, dim[1] * res - res / 2, num=dim[1])
y = np.linspace(res / 2, dim[0] * res - res / 2, num=dim[0])
xx, yy = np.meshgrid(x, y)
bottom = (yy >= 0.25*edge*res)
left = (yy <= 0.75/0.5 * xx)
right = np.fliplr(left)#(yy <= (edge-1)*res - 0.75/0.5 * (xx - 0.5*(edge-1)*res))
shape_mag = np.logical_and(np.logical_and(left, right), bottom)
x_mag = np.array(np.ones(dim)) * np.cos(beta) * shape_mag
y_mag = np.array(np.ones(dim)) * np.sin(beta) * shape_mag
z_mag = np.array(np.zeros(dim))
if (True):
fig = plt.figure()
fig.add_subplot(111, aspect='equal')
plt.quiver(x_mag, y_mag, pivot='middle', angles='xy', scale_units='xy',
scale=1, headwidth=6, headlength=7)
xx = np.reshape(xx,(-1))
yy = np.reshape(yy,(-1))
zz = np.array(np.ones(dim[0] * dim[1]) * res / 2)
x_mag = np.reshape(x_mag,(-1))
y_mag = np.reshape(y_mag,(-1))
z_mag = np.array(np.zeros(dim[0] * dim[1]))
data = np.array([xx, yy, zz, x_mag, y_mag, z_mag]).T
with open(filename,'w') as mag_file:
mag_file.write('LLGFileCreator2D: %s\n' % filename.replace('.txt', ''))
mag_file.write(' %d %d %d\n' % (dim[1], dim[0], 1))
mag_file.writelines('\n'.join(' '.join('{:7.6e}'.format(cell)
for cell in row) for row in data) )