Remove x axis and y axis black lines with matplotlib

import numpy as np
import matplotlib.pyplot as plt

tau = np.arange(-5, 5, 0.01)
a = 0.4  

sigma = a*tau 
x = 1/a*np.cosh(sigma)  
y = 1/a*np.sinh(sigma)

fig, ax = plt.subplots()
ax.plot(x, y, c='black')

# approximate the curve by a cubic
dxds = np.poly1d(np.polyfit(sigma, x, 3)).deriv()
dyds = np.poly1d(np.polyfit(sigma, y, 3)).deriv()

xs, ys, dxs, dys = [], [], [], []
for s in np.linspace(-1, 1, 5):
    # evaluate the derivative at s
    dx = np.polyval(dxds, s)
    dy = np.polyval(dyds, s)

    # record the x, y location and dx, dy tangent vector associated with s
    xi = 1/a*np.cosh(s)  
    yi = 1/a*np.sinh(s)
    xs.append(xi)
    ys.append(yi)
    dxs.append(dx)
    dys.append(dy)
    if s == 0:
        ax.text(xi-0.75, yi+1.5, '$u$', transform=ax.transData) 
        ax.annotate('$a^{-1}$',
                    xy=(xi, yi), xycoords='data',
                    xytext=(25, -5), textcoords='offset points',
                    verticalalignment='top', horizontalalignment='left', 
                    arrowprops=dict(arrowstyle='-', shrinkB=7))

ax.quiver(xs, ys, dxs, dys, scale=1.8, color='black', scale_units='xy', angles='xy',
          width=0.01)
ax.plot(xs, ys, 'ko')

# http://stackoverflow.com/a/13430772/190597 (lucasg)
ax.set_xlim(-0.1, x.max())
left, right = ax.get_xlim()
low, high = ax.get_ylim()
ax.arrow(0, 0, right, 0, length_includes_head=True, head_width=0.15 )
ax.arrow(0, low, 0, high-low, length_includes_head=True, head_width=0.15 ) 
ax.text(0.03, 1, '$t$', transform=ax.transAxes)
ax.text(1, 0.47, '$x$', transform=ax.transAxes)

plt.axis('off')
ax.set_aspect('equal')
plt.show()

$(function () {
    var chart = new Highcharts.Chart({
        chart: {
            renderTo: 'container',
          ignoreHiddenSeries : false
        },

        xAxis: {
        },

        series: [{
            data: [29.9, 71.5, 106.4, 129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4]        
        }, {
            data: [129.2, 144.0, 176.0, 135.6, 148.5, 216.4, 194.1, 95.6, 54.4, 29.9, 71.5, 106.4]        
        }]
    });

    // the button action
  var series = chart.series[0];    
  series.hide();
  series = chart.series[1];    
  series.hide();
});

t = arange(-2, 2, 0.1)
y2 = exp(-t)
axhline(0,color='red') # x = 0
axvline(0,color='red') # y = 0
grid()
plot(t, y2, '-')
show()

from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import numpy as np

def make_dashedLines(x,y,z,ax):
    for i in range(0, len(x)):
        x_val, y_val, z_val = x[i],y[i],z[i]
        ax.plot([0,x_val],[y_val,y_val],zs=[0,0], linestyle="dashed",color="black")
        ax.plot([x_val,x_val],[0,y_val],zs=[0,0], linestyle="dashed",color="black")
        ax.plot([x_val,x_val],[y_val,y_val],zs=[0,z_val], linestyle="dashed",color="black")

fig = plt.figure()

ax = fig.add_subplot(111, projection='3d')
x = [1,1,-1]
y = [1,-1,1]
z = [1,1,-1]

ax.scatter( x,y,z, c='r', marker='o')
make_dashedLines(x,y,z,ax)

# Make a 3D quiver plot
x, y, z = np.array([[-2,0,0],[0,-2,0],[0,0,-2]])
u, v, w = np.array([[4,0,0],[0,4,0],[0,0,4]])
ax.quiver(x,y,z,u,v,w,arrow_length_ratio=0.1, color="black")
ax.grid(False)
ax.set_xlabel('X')
ax.set_ylabel('Y')
ax.set_zlabel('Z')

ax.set_xlim(-2,2)
ax.set_ylim(-2,2)
ax.set_zlim(-2,2)

plt.show()

col_to_draw = [col for col in df.columns if col!='col0']

# if your data frame is indexed as 0,1,2,... ignore this step
tmp_df = df.reset_index()

ax = tmp_df[col_to_draw].plot(figsize=(10,6))
xtick_vals = ax.get_xticks()
ax.set_xticklabels(tmp_df.col0[xtick_vals].tolist())