python_runge_kutta.ipynb

Kernel: Python 3 (Anaconda)

import matplotlib.pyplot as plt
from numpy.random import rand


for color in ['red', 'green', 'blue']:
    n = 750
    x, y = rand(2, n)
    scale = 200.0 * rand(n)
    plt.scatter(x, y, c=color, s=scale, label=color,
                alpha=0.3, edgecolors='none')

plt.legend()
plt.grid(True)

plt.show()

from scipy.integrate import ode

import numpy as np
from scipy.integrate import ode
import matplotlib.pyplot as plt
import warnings


def logistic(t, y, r):
    return r * y * (1.0 - y)

r = .01
t0 = 0
y0 = 1e-5
t1 = 5000.0

#backend = 'vode'
backend = 'dopri5'
#backend = 'dop853'

solver = ode(logistic).set_integrator(backend, nsteps=1)
solver.set_initial_value(y0, t0).set_f_params(r)
# suppress Fortran-printed warning
solver._integrator.iwork[2] = -1

sol = []
warnings.filterwarnings("ignore", category=UserWarning)
while solver.t < t1:
    solver.integrate(t1, step=True)
    sol.append([solver.t, solver.y])
warnings.resetwarnings()
sol = np.array(sol)

plt.plot(sol[:,0], sol[:,1], 'b.-')
plt.show()

import matplotlib as mpl
import matplotlib.pyplot as plt

cmap = mpl.cm.get_cmap('bwr')
norm = mpl.colors.Normalize(vmin=0,vmax=1.)

ind = range(0,5)
vals = [1.5,0.45,3.34,2.78,1.2]
pval = [1,1,0.4,1,.1]
cols = [cmap(norm(x)) for x in pval]
plt.bar(ind,vals,1.0,color=cols)
plt.text(0,.5,'3030',rotation='vertical',horizontalalignment='center')
plt.text(1,.5,'3050',rotation='vertical',horizontalalignment='center')
plt.text(2,.5,'4050',rotation='vertical',horizontalalignment='center')
plt.xticks(ind,5*[''])
cbar = mpl.colorbar.ColorbarBase(plt.gca(),cmap=cmap, norm=norm)
plt.show()
plt.colorbar(cbar)
plt.show()
print(cols)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-4-db226518434a> in <module>()
     16 cbar = mpl.colorbar.ColorbarBase(plt.gca(),cmap=cmap, norm=norm)
     17 plt.show()
---> 18 plt.colorbar(cbar)
     19 plt.show()
     20 print(cols)
/projects/anaconda3/lib/python3.5/site-packages/matplotlib/pyplot.py in colorbar(mappable, cax, ax, **kw)
   2260         ax = gca()
   2261 
-> 2262     ret = gcf().colorbar(mappable, cax = cax, ax=ax, **kw)
   2263     return ret
   2264 colorbar.__doc__ = matplotlib.colorbar.colorbar_doc
/projects/anaconda3/lib/python3.5/site-packages/matplotlib/figure.py in colorbar(self, mappable, cax, ax, use_gridspec, **kw)
   1600                 cax, kw = cbar.make_axes(ax, **kw)
   1601         cax._hold = True
-> 1602         cb = cbar.colorbar_factory(cax, mappable, **kw)
   1603 
   1604         self.sca(current_ax)
/projects/anaconda3/lib/python3.5/site-packages/matplotlib/colorbar.py in colorbar_factory(cax, mappable, **kwargs)
   1345         cb = ColorbarPatch(cax, mappable, **kwargs)
   1346     else:
-> 1347         cb = Colorbar(cax, mappable, **kwargs)
   1348 
   1349     cid = mappable.callbacksSM.connect('changed', cb.on_mappable_changed)
/projects/anaconda3/lib/python3.5/site-packages/matplotlib/colorbar.py in __init__(self, ax, mappable, **kw)
    899         # Ensure the given mappable's norm has appropriate vmin and vmax set
    900         # even if mappable.draw has not yet been called.
--> 901         mappable.autoscale_None()
    902 
    903         self.mappable = mappable
/projects/anaconda3/lib/python3.5/site-packages/matplotlib/cm.py in autoscale_None(self)
    345         """
    346         if self._A is None:
--> 347             raise TypeError('You must first set_array for mappable')
    348         self.norm.autoscale_None(self._A)
    349         self.changed()
TypeError: You must first set_array for mappable

norm

norm(0)