From 94b6d3246c72eb3cae58a2fd18771e3c2c3e7cb2 Mon Sep 17 00:00:00 2001
From: zhang <zch921005@126.com>
Date: Sun, 21 Aug 2022 09:41:53 +0800
Subject: copy

---
 fun_math/r_w.py         | 66 +++++++++++++++++++++++++++++++++++++++++++++++++
 fun_math/random_walk.py | 14 +++++++++++
 2 files changed, 80 insertions(+)
 create mode 100644 fun_math/r_w.py
 create mode 100644 fun_math/random_walk.py

(limited to 'fun_math')

diff --git a/fun_math/r_w.py b/fun_math/r_w.py
new file mode 100644
index 0000000..c1eb3ed
--- /dev/null
+++ b/fun_math/r_w.py
@@ -0,0 +1,66 @@
+
+import matplotlib.pyplot as plt
+import matplotlib.animation as animation
+import numpy as np
+
+np.random.seed(1234)
+
+
+def random_walk(N):
+    """
+    Simulates a discrete random walk
+    :param int N : the number of steps to take
+    """
+    # event space: set of possible increments
+    increments = np.array([1, -1])
+    # the probability to generate 1
+    p = 0.5
+
+    # the epsilon values
+    random_increments = np.random.choice(increments, N, p)
+    # calculate the random walk
+    random_walk = np.cumsum(random_increments)
+
+    # return the entire walk and the increments
+    return random_walk, random_increments
+
+
+# generate a random walk
+N = 500
+X, epsilon = random_walk(N)
+
+# normalize the random walk using the Central Limit Theorem
+# X = X * np.sqrt(1. / N)
+
+fig = plt.figure(figsize=(21, 10))
+ax = plt.axes(xlim=(0, N), ylim=(np.min(X) - 0.5, np.max(X) + 0.5))
+line, = ax.plot([], [], lw=2, color='#0492C2')
+ax.set_xticks(np.arange(0, N+1, 50))
+ax.set_yticks(np.arange(np.min(X) - 0.5, np.max(X) + 0.5, 0.2))
+ax.set_title('2D Random Walk', fontsize=22)
+ax.set_xlabel('Steps', fontsize=18)
+ax.set_ylabel('Value', fontsize=18)
+ax.tick_params(labelsize=16)
+ax.grid(True, which='major', linestyle='--', color='black', alpha=0.4)
+
+# initialization function
+def init():
+    # creating an empty plot/frame
+    line.set_data([], [])
+    return line,
+
+# lists to store x and y axis points
+xdata, ydata = [], []
+
+# animation function
+def animate(i):
+    y = X[i]
+    # appending new points to x, y axes points list
+    xdata.append(i)
+    ydata.append(y)
+    line.set_data(xdata, ydata)
+    return line,
+
+# call the animator
+anim = animation.FuncAnimation(fig, animate, init_func=init, frames=N, interval=20, blit=True)
+anim.save('random_walk.gif',writer='imagemagick')
\ No newline at end of file
diff --git a/fun_math/random_walk.py b/fun_math/random_walk.py
new file mode 100644
index 0000000..b425fcb
--- /dev/null
+++ b/fun_math/random_walk.py
@@ -0,0 +1,14 @@
+
+import random
+
+
+# N, S, W, E
+choices = [(0, 1), (0, -1), (-1, 0), (1, 0)]
+
+
+def rand_walk(n, p0=[]):
+    if p0 is None:
+        p0 = [0, 0]
+    pass
+
+
-- 
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