Python numpy.exp函数代码示例

    def plot_open_close(self, fig = None, savefig = True):
        '''
        Plot the open period versus shut periods.
        '''

        stretch_list = self.cluster_data.compute_open_close()
        mode_num = len(stretch_list)


        if fig is None:
            fig = plt.figure()
        ax = fig.add_subplot(111)
        cmap = np.linspace(0,1,mode_num)

        for index, stretch in enumerate(stretch_list):
            ax.scatter(stretch['open_period'], stretch['shut_period'],
                       facecolors='none',
                       edgecolors=plt.cm.spectral(cmap[index]),
                       s=1, label = str(index + 1))
            #ax.scatter(stretch['mean_open'], stretch['mean_shut'],
            #           color=plt.cm.spectral(cmap[index]),
             #          s=50, label = str(index + 1))
    
        ax.legend()
        ax.set_xscale('log')
        ax.set_yscale('log')
        ax.set_ylim([0.3, np.exp(7)])
        ax.set_xlim([0.3, np.exp(5)])
        ax.set_xlabel('Open period (ms in log scale)')
        ax.set_ylabel('Shut period (ms in log scale)')
        ax.set_title('Open/Shut')
        if savefig:
            fig.savefig(os.path.join(self.filepath,self.name+'Open_Shut.png'),dpi=150)

def sample(scores, temperature=1.0):
    """
    Sampling words (each sample is drawn from a categorical distribution).

    In:
        scores - array of size #samples x #classes; 
            every entry determines a score for sample i having class j
        temperature - temperature for the predictions;
            the higher the flatter probabilities and hence more random answers

    Out:
        set of indices chosen as output, a vector of size #samples
    """
    logscores = np.log(scores) / temperature

    # numerically stable version
    normalized_logscores= logscores - np.max(logscores, axis=-1)[:, np.newaxis]
    margin_logscores = np.sum(np.exp(normalized_logscores),axis=-1)
    probs = np.exp(normalized_logscores) / margin_logscores[:,np.newaxis]

    draws = np.zeros_like(probs)
    num_samples = probs.shape[0]
    # we use 1 trial to mimic categorical distributions using multinomial
    for k in xrange(num_samples):
        draws[k,:] = np.random.multinomial(1,probs[k,:],1)
    return np.argmax(draws, axis=-1)

def mean_quadratic_weighted_kappa(kappas, weights=None):
    """
    Calculates the mean of the quadratic
    weighted kappas after applying Fisher's r-to-z transform, which is
    approximately a variance-stabilizing transformation.  This
    transformation is undefined if one of the kappas is 1.0, so all kappa
    values are capped in the range (-0.999, 0.999).  The reverse
    transformation is then applied before returning the result.

    mean_quadratic_weighted_kappa(kappas), where kappas is a vector of
    kappa values

    mean_quadratic_weighted_kappa(kappas, weights), where weights is a vector
    of weights that is the same size as kappas.  Weights are applied in the
    z-space
    """
    kappas = np.array(kappas, dtype=float)
    if weights is None:
        weights = np.ones(np.shape(kappas))
    else:
        weights = weights / np.mean(weights)

    # ensure that kappas are in the range [-.999, .999]
    kappas = np.array([min(x, .999) for x in kappas])
    kappas = np.array([max(x, -.999) for x in kappas])

    z = 0.5 * np.log((1 + kappas) / (1 - kappas)) * weights
    z = np.mean(z)
    return (np.exp(2 * z) - 1) / (np.exp(2 * z) + 1)

    def solveParams(self):
        # Given the specified values for w, z1 and z2, determine the offsets
        # xc and zc required to match a catenary to our cable.  This is done
        # algerbraically.  The deriviation of the equation was performed with
        # the sympy package.

        w = self.w
        a = self.a
        zd = self.z2 - self.z1

        # calculate some repeated elements
        e2wa = np.exp(2 * w / a)
        ewa = np.exp(w / a)
        a2 = a ** 2

        # calculate the 3 components
        c1 = (a2 * e2wa - 2 * a2 * ewa + a2 + zd ** 2 * ewa) * ewa
        c2 = (-2 * a * e2wa + 2 * a * ewa)
        c3 = zd / (a * (ewa - 1))

        # Determine the x offset ...
        self.xc = a * np.log(2 * np.abs(np.sqrt(c1) / c2) + c3)

        # ... and from this the y offset
        self.zc = self.z1 - a * np.cosh(self.xc / a)

 def __set_static_gaus_pmfs(self):
     if np.logical_not(self.off_buff.is_full()):
         print "The long term buffer is not yet full.  This may give undesirable results"
     
     # median RSS of off-state buffer
     cal_med = self.off_buff.get_no_nan_median()
     
     if (np.sum(cal_med == 127) > 0) | (np.sum(np.isnan(cal_med)) > 0):
         sys.stderr.write('At least one link has a median of 127 or is nan\n\n')
         quit()
          
     if (np.sum(np.isnan(self.off_buff.get_nanvar())) > 0):
         sys.stderr.write('the long term buffer has a nan')
         quit()
     
     cal_med_mat = np.tile(cal_med,(self.V_mat.shape[1],1)).T
     
     # variance of RSS during calibration
     cal_var = np.maximum(self.off_buff.get_nanvar(),self.omega) #3.0 
     cal_var_mat = np.tile(cal_var,(self.V_mat.shape[1],1)).T
     
     # Compute the off_link emission probabilities for each link
     x = np.exp(- (self.V_mat - cal_med_mat)**2/(2*cal_var_mat/1.0)) # 1.0
     self.off_links = self.__normalize_pmf(x)
     
     # Compute the on_link emission probabilities for each link
     x = np.exp(- (self.V_mat - (cal_med_mat-self.Delta))**2/(self.eta*2*cal_var_mat)) # 3
     self.on_links = self.__normalize_pmf(x) 

  def testCustomGradient(self):
    dtype = dtypes.float32

    @function.Defun(dtype, dtype, dtype)
    def XentLossGrad(logits, labels, dloss):
      dlogits = array_ops.reshape(dloss, [-1, 1]) * (
          nn_ops.softmax(logits) - labels)
      dlabels = array_ops.zeros_like(labels)
      # Takes exp(dlogits) to differentiate it from the "correct" gradient.
      return math_ops.exp(dlogits), dlabels

    @function.Defun(dtype, dtype, grad_func=XentLossGrad)
    def XentLoss(logits, labels):
      return math_ops.reduce_sum(labels * math_ops.log(nn_ops.softmax(logits)),
                                 1)

    g = ops.Graph()
    with g.as_default():
      logits = array_ops.placeholder(dtype)
      labels = array_ops.placeholder(dtype)
      loss = XentLoss(logits, labels)
      dlogits = gradients_impl.gradients([loss], [logits])

    x = np.random.uniform(-10., 10., size=(4, 9)).astype(np.float32)
    prob = np.exp(x) / np.sum(np.exp(x), 1, keepdims=1)
    y = np.random.uniform(-10., 10., size=(4, 9)).astype(np.float32)
    for cfg in _OptimizerOptions():
      tf_logging.info("cfg = %s", cfg)
      with session.Session(graph=g, config=cfg) as sess:
        out, = sess.run(dlogits, {logits: x, labels: y})
      self.assertAllClose(out, np.exp(prob - y))

def CRRbinomial(S, K, T, rf, sigma, n):
    '''
    Option pricing using binomial tree, no dividend
    :param S: underlying current prince
    :param K: option strke price
    :param T: expire date
    :param rf: risk-free rate
    :param sigma: volatility
    :param n: number of periods to T
    :return:
    '''
    dt = float(T)/n
    u = np.exp(sigma * (dt**0.5))
    d= 1./u
    p = (np.exp(rf*dt)-d)/(u-d)

    euroCall, euroPut = 0, 0

    for idx in xrange(0, n+1):
        prob = spmisc.comb(n, idx)* (p**idx) * (1-p)**(n-idx)
        euroCall += prob*max(S*(u**idx)*(d**(n-idx))-K, 0)
        euroPut += prob*max(K-S*(u**idx)*(d**(n-idx)), 0)

    euroCall *= np.exp(-rf*T)
    euroPut *= np.exp(-rf*T)
    return euroCall, euroPut

 def update(self,proposal,logp,bad,i):
     logps = self.logps[i-1]
     thresh = self.thresh
     if logp>logps:
         self.logps[i] = logp
         self.trace[i] = proposal
         self.dets.append([d.value for d in self.deterministics])
         self.nbad = 0
         self.stuck = False
         self.temp = 1.
         return
     self.nbad += 1
     if self.nbad>self.thresh and self.stuck==False:
         self.stuck = True
         self.logpTmp = logps
     if self.stuck==True:
         r = log(rand())*self.temp
         print 'stuck',i,logps,self.logpTmp,logp,r,logp-self.logpTmp
         if logp-self.logpTmp>r:
             self.logpTmp = logp
             self.temp /= numpy.exp(1./thresh)
         else:
             self.temp *= numpy.exp(1./thresh)
     self.logps[i] = self.logps[i-1]
     self.trace[i] = self.trace[i-1].copy()
     self.dets.append(self.dets[-1])

    def logLikelihood(self, obs_seq, num_cluster, error_rate_dict, switch_rate_dict):
        """

        :param obs_seq: state list of the same length as observation sequence
        :param num_cluster: int
        :param error_rate_dict: dict
        :param switch_rate_dict: dict
        :return: log likelihood
        """
        pi = [1/num_cluster] * num_cluster
        path_length = len(obs_seq)

        alpha_dict = dict()

        alpha_dict[0] = dict(zip(range(num_cluster), [np.log(pi[i]) + np.log(error_rate_dict[i][obs_seq[0]])
                                                      for i in range(num_cluster)]))

        for t in range(path_length-1):
            alpha_dict[t+1] = dict()
            for j in range(num_cluster):
                log_alpha_j = [(alpha_dict[t][i] + np.log(switch_rate_dict[i][j])) for i in range(num_cluster)]
                max_log_alpha_j = max(log_alpha_j)
                sum_residual = np.sum(np.exp(log_alpha_j - max_log_alpha_j))
                final = max_log_alpha_j + np.log(sum_residual)
                alpha_dict[t+1][j] = final + np.log(error_rate_dict[j][obs_seq[t + 1]])

        alpha_df = pd.DataFrame.from_dict(alpha_dict)
        max_final = max(alpha_df.ix[:, path_length-1])

        llk = max_final + np.log(np.sum(np.exp(alpha_df.ix[:, path_length-1] - max_final)))

        return llk

def test_solve_poisson_becke_sa():
    sigma = 8.0
    rtf = ExpRTransform(1e-4, 1e2, 500)
    r = rtf.get_radii()
    rhoy = np.exp(-0.5*(r/sigma)**2)/sigma**3/(2*np.pi)**1.5
    rhod = np.exp(-0.5*(r/sigma)**2)/sigma**3/(2*np.pi)**1.5*(-r/sigma)/sigma
    rho = CubicSpline(rhoy, rhod, rtf)
    v = solve_poisson_becke([rho])[0]

    s2s = np.sqrt(2)*sigma
    soly = erf(r/s2s)/r
    sold = np.exp(-(r/s2s)**2)*2/np.sqrt(np.pi)/s2s/r - erf(r/s2s)/r**2

    if False:
        import matplotlib.pyplot as pt
        n = 10
        pt.clf()
        pt.plot(r[:n], soly[:n], label='exact')
        pt.plot(r[:n], v.y[:n], label='spline')
        pt.legend(loc=0)
        pt.savefig('denu.png')

    assert abs(v.y - soly).max()/abs(soly).max() < 1e-6
    assert abs(v.dx - sold).max()/abs(sold).max() < 1e-4
    # Test the boundary condition at zero and infinity
    assert v.extrapolation.l == 0
    np.testing.assert_allclose(v.extrapolation.amp_left, np.sqrt(2/np.pi)/sigma)
    np.testing.assert_allclose(v.extrapolation.amp_right, 1.0)

    def __init__(self, ps=None, sigma_v=0.0, redshift=0.0, **kwargs):
        if ps == None:
            from os.path import join, dirname
            #psfile = join(dirname(__file__),"data/ps_z1.5.dat")
            #psfile = join(dirname(__file__),"data/wigglez_halofit_z1.5.dat")
            psfile = join(dirname(__file__),"data/wigglez_halofit_z0.8.dat")
            print "loading matter power file: " + psfile
            redshift = 0.8

            #pk_interp = cs.LogInterpolater.fromfile(psfile)
            pwrspec_data = np.genfromtxt(psfile)

            (log_k, log_pk) = (np.log(pwrspec_data[:,0]), \
                               np.log(pwrspec_data[:,1]))

            logpk_interp = interpolate.interp1d(log_k, log_pk,
                                                bounds_error=False,
                                                fill_value=np.min(log_pk))

            pk_interp = lambda k: np.exp(logpk_interp(np.log(k)))

            kstar = 7.0
            ps = lambda k: np.exp(-0.5 * k**2 / kstar**2) * pk_interp(k)

        self._sigma_v = sigma_v

        RedshiftCorrelation.__init__(self, ps_vv=ps, redshift=redshift)

    def _compute_influence_kernel(self, iter, dqd):
        """Compute the neighborhood kernel for some iteration.

        Parameters
        ----------
        iter : int
          The iteration for which to compute the kernel.
        dqd : array (nrows x ncolumns)
          This is one quadrant of Euclidean distances between Kohonen unit
          locations.
        """
        # compute radius decay for this iteration
        curr_max_radius = self.radius * np.exp(-1.0 * iter / self.iter_scale)

        # same for learning rate
        curr_lrate = self.lrate * np.exp(-1.0 * iter / self.iter_scale)

        # compute Gaussian influence kernel
        infl = np.exp((-1.0 * dqd) / (2 * curr_max_radius * iter))
        infl *= curr_lrate

        # hard-limit kernel to max radius
        # XXX is this really necessary?
        infl[dqd > curr_max_radius] = 0.

        return infl

def firwin_complex_bandpass(num_taps, cutoffs, window='hamming'):
    width, center = max(cutoffs) - min(cutoffs), (cutoffs[0] + cutoffs[1]) / 2
    b = scipy.signal.firwin(num_taps, width / 2, window='rectangular', scale=False)
    b = b * numpy.exp(1j * numpy.pi * center * numpy.arange(len(b)))
    b = b * scipy.signal.get_window(window, num_taps, False)
    b = b / numpy.sum(b * numpy.exp(-1j * numpy.pi * center * (numpy.arange(num_taps) - (num_taps - 1) / 2)))
    return b.astype(numpy.complex64)

def convolve_template():
    from plot_Profile_evolution import all_obs
    import numpy as np

    date_list, observations = all_obs()
    x = np.arange(512 - 25 - 50, 512 + 45 + 51)

    delay = []
    for n in observations:
        best_mu = 0
        best_corr = 0

        for mu in np.linspace(512 - 25, 512 + 45, 701):
            template = np.exp(-(x - 512) ** 2 / (2.0 * 6.2 ** 2)) + 0.09 * np.exp(-(x - mu) ** 2 / (2.0 * 8.0 ** 2))
            template /= template.max()
            corr = np.correlate(n, template, mode="valid").max()

            if corr > best_corr:
                best_corr = corr
                best_mu = mu

        delay.append(best_mu - 512)

    plt.plot(date_list, delay, "ko")
    plt.show()

 def all_GL(self, q, maxpiv=None):
     """return (piv, f_binodal_gas, f_binodal_liquid, f_spinodal_gas, f_spinodal_liquid) at insersion works piv sampled between the critical point and maxpiv (default to 2.2*critical pressure)"""
     fc, pivc = self.critical_point(q)
     Fc = np.log(fc)
     #start sensibly above the critical point
     startp = pivc*1.1
     fm = fminbound(self.mu, fc, self.maxf(), args=(startp, q))
     fM = fminbound(lambda f: -self.pv(f, startp, q), 0, fc)
     initial_guess = np.log([0.5*fM, 0.5*(fm+self.maxf())])
     #construct the top of the GL binodal
     if maxpiv is None:
         maxpiv = startp*2
     topp = 1./np.linspace(1./startp, 1./maxpiv)
     topGL = [initial_guess]
     for piv in topp:
         topGL.append(self.binodalGL(piv, q, topGL[-1]))
     #construct the GL binodal between the starting piv and the critical point
     botp = np.linspace(startp, pivc)[:-1]
     botGL = [initial_guess]
     for piv in botp:
         botGL.append(self.binodalGL(piv, q, botGL[-1]))
     #join the two results and convert back from log
     binodal = np.vstack((
         [[pivc, fc, fc]],
         np.column_stack((botp, np.exp(botGL[1:])))[::-1],
         np.column_stack((topp, np.exp(topGL[1:])))[1:]
         ))
     #spinodal at the same pivs
     spinodal = self.spinodalGL(q, binodal[:,0])
     #join everything
     return np.column_stack((binodal, spinodal[:,1:]))