def _blur(radius, theta, amount=0.07, random_state="random-seed"):
"""Blur the positions around the centroid of the spiralarm.
The given positions are blurred by drawing a displacement in radius from
a normal distribution, with sigma = amount * radius. And a direction
theta from a uniform distribution in the interval [0, 2 * pi].
Parameters
----------
radius : `~astropy.units.Quantity`
Radius coordinate
theta : `~astropy.units.Quantity`
Angle coordinate
amount: float, optional
Amount of blurring of the position, given as a fraction of `radius`.
random_state : {int, 'random-seed', 'global-rng', `~numpy.random.RandomState`}
Defines random number generator initialisation.
Passed to `~gammapy.utils.random.get_random_state`.
"""
random_state = get_random_state(random_state)
dr = Quantity(
abs(random_state.normal(0, amount * radius, radius.size)), "kpc")
dtheta = Quantity(random_state.uniform(0, 2 * np.pi, radius.size),
"rad")
x, y = cartesian(radius, theta)
dx, dy = cartesian(dr, dtheta)
return polar(x + dx, y + dy)
ax_cartesian.set_ylim(-20, 20)
ax_cartesian.set_xlabel('x [kpc]', labelpad=2)
ax_cartesian.set_ylabel('y [kpc]', labelpad=-4)
ax_cartesian.plot(
0, 8, color='k', markersize=10,
fillstyle='none', marker='*', linewidth=2,
)
ax_cartesian.annotate(
'Sun', xy=(0, 8), xycoords='data', xytext=(-15, 15),
arrowprops=dict(arrowstyle="->", color='k'), weight=400,
)
plt.grid(True)
# TODO: document what these magic numbers are or simplify the code
# `other_idx = [95, 90, 80, 80]` and below `theta_idx = int(other_idx * 0.97)`
for spiral_idx, other_idx in zip(range(4), [95, 90, 80, 80]):
spiralarm_name = spiral.spiralarms[spiral_idx]
theta_0 = spiral.theta_0[spiral_idx].value
theta = Quantity(np.linspace(theta_0, theta_0 + 2 * np.pi, 100), 'rad')
x, y = spiral.xy_position(theta=theta, spiralarm_index=spiral_idx)
ax_cartesian.plot(x.value, y.value, color='k')
rad, phi = polar(x[other_idx], y[other_idx])
x_pos, y_pos = cartesian(rad + Quantity(1, 'kpc'), phi)
theta_idx = int(other_idx * 0.97)
rotation = theta[theta_idx].to('deg').value
ax_cartesian.text(x_pos.value, y_pos.value, spiralarm_name,
ha='center', va='center', rotation=rotation - 90, weight=400)
plt.show()
fillstyle='none',
marker='*',
linewidth=2)
ax_cartesian.annotate('Sun',
xy=(0, 8),
xycoords='data',
xytext=(-15, 15),
arrowprops=dict(arrowstyle="->", color='k'),
weight=400)
plt.grid(True)
ind = [95, 90, 80, 80]
for i in range(4):
theta_0 = spiral.theta_0[i].value
theta = Quantity(np.linspace(theta_0, theta_0 + 2 * np.pi, 100), 'rad')
x, y = spiral.xy_position(theta=theta, spiralarm_index=i)
ax_cartesian.plot(x.value, y.value, color='k')
rad, phi = polar(x[ind[i]], y[ind[i]])
x_pos, y_pos = cartesian(rad + Quantity(1, 'kpc'), phi)
rotation = theta[ind[i] * 0.97].to('deg').value
ax_cartesian.text(x_pos.value,
y_pos.value,
spiral.spiralarms[i],
ha='center',
va='center',
rotation=rotation - 90,
weight=400)
plt.show()
ax_cartesian.set_aspect('equal')
ax_polar = fig.add_axes(rect, polar=True, frameon=False)
ax_polar.axes.get_xaxis().set_ticklabels([])
ax_polar.axes.get_yaxis().set_ticklabels([])
ax_cartesian.plot(catalog['x'], catalog['y'], marker='.',
linestyle='none', markersize=5, alpha=0.3, fillstyle='full')
ax_cartesian.set_xlim(-20, 20)
ax_cartesian.set_ylim(-20, 20)
ax_cartesian.set_xlabel('x [kpc]', labelpad=2)
ax_cartesian.set_ylabel('y [kpc]', labelpad=-4)
ax_cartesian.plot(0, 8, color='k', markersize=10, fillstyle='none', marker='*', linewidth=2)
ax_cartesian.annotate('Sun', xy=(0, 8), xycoords='data',
xytext=(-15, 15), arrowprops=dict(arrowstyle="->", color='k'), weight=400)
plt.grid(True)
ind = [95, 90, 80, 80]
for i in range(4):
theta_0 = spiral.theta_0[i].value
theta = Quantity(np.linspace(theta_0, theta_0 + 2 * np.pi, 100), 'rad')
x, y = spiral.xy_position(theta=theta, spiralarm_index=i)
ax_cartesian.plot(x.value, y.value, color='k')
rad, phi = polar(x[ind[i]], y[ind[i]])
x_pos, y_pos = cartesian(rad + Quantity(1, 'kpc'), phi)
rotation = theta[ind[i] * 0.97].to('deg').value
ax_cartesian.text(x_pos.value, y_pos.value, spiral.spiralarms[i],
ha='center', va='center', rotation=rotation - 90, weight=400)
plt.show()
xytext=(-15, 15),
arrowprops=dict(arrowstyle="->", color="k"),
weight=400,
)
plt.grid(True)
# TODO: document what these magic numbers are or simplify the code
# `other_idx = [95, 90, 80, 80]` and below `theta_idx = int(other_idx * 0.97)`
for spiral_idx, other_idx in zip(range(4), [95, 90, 80, 80]):
spiralarm_name = spiral.spiralarms[spiral_idx]
theta_0 = spiral.theta_0[spiral_idx].value
theta = Quantity(np.linspace(theta_0, theta_0 + 2 * np.pi, 100), "rad")
x, y = spiral.xy_position(theta=theta, spiralarm_index=spiral_idx)
ax_cartesian.plot(x.value, y.value, color="k")
rad, phi = polar(x[other_idx], y[other_idx])
x_pos, y_pos = cartesian(rad + Quantity(1, "kpc"), phi)
theta_idx = int(other_idx * 0.97)
rotation = theta[theta_idx].to("deg").value
ax_cartesian.text(
x_pos.value,
y_pos.value,
spiralarm_name,
ha="center",
va="center",
rotation=rotation - 90,
weight=400,
)
plt.show()