eckity.genetic_encodings.gp.tree.functions

  1"""
  2This module implements functions used in the function (internal) nodes of a GP tree.
  3Note: all functions work on numpy arrays.
  4"""
  5
  6import numpy as np
  7
  8
  9def f_add(x, y):
 10    """x+y"""
 11    return np.add(x, y)
 12
 13
 14def f_sub(x, y):
 15    """x-y"""
 16    return np.subtract(x, y)
 17
 18
 19def f_mul(x, y):
 20    """x*y"""
 21    return np.multiply(x, y)
 22
 23
 24def f_div(x, y):
 25    """protected division: if abs(y) > 0.001 return x/y else return 0"""
 26    with np.errstate(divide='ignore', invalid='ignore'):
 27        return np.where(np.abs(y) > 0.001, np.divide(x, y), 0.)
 28
 29
 30def f_sqrt(x):
 31    """protected square root: sqrt(abs(x))"""
 32    return np.sqrt(np.absolute(x))
 33
 34
 35def f_log(x):
 36    """protected log: if abs(x) > 0.001 return log(abs(x)) else return 0"""
 37    with np.errstate(divide='ignore', invalid='ignore'):
 38        return np.where(np.abs(x) > 0.001, np.log(np.abs(x)), 0.)
 39
 40
 41def f_abs(x):
 42    """absolute value of x"""
 43    return np.absolute(x)
 44
 45
 46def f_neg(x):
 47    """negative of x"""
 48    return np.negative(x)
 49
 50
 51def f_inv(x):
 52    """protected inverse: if abs(x) > 0.001 return 1/x else return 0"""
 53    # with np.errstate(divide='ignore', invalid='ignore'):
 54    #     return np.where(np.abs(x) > 0.001, 1. / x, 0.)
 55    return f_div(1, x)
 56
 57
 58def f_max(x, y):
 59    """maximum(x,y)"""
 60    return np.maximum(x, y)
 61
 62
 63def f_min(x, y):
 64    """minimum(x,y)"""
 65    return np.minimum(x, y)
 66
 67
 68def f_sin(x):
 69    """sin(x)"""
 70    return np.sin(x)
 71
 72
 73def f_cos(x):
 74    """cos(x)"""
 75    return np.cos(x)
 76
 77
 78def f_tan(x):
 79    """tan(x)"""
 80    return np.tan(x)
 81
 82
 83def f_iflte0(x, y, z):
 84    """if x <= 0 return y else return z"""
 85    return np.where(x <= 0, y, z)
 86
 87
 88def f_ifgt0(x, y, z):
 89    """if x > 0 return y else return z"""
 90    return np.where(x > 0, y, z)
 91
 92
 93def f_iflte(x, y, z, w):
 94    """if x <= y return z else return w"""
 95    return np.where(x <= y, z, w)
 96
 97
 98def f_ifgt(x, y, z, w):
 99    """if x > y return z else return w"""
100    return np.where(x > y, z, w)
101
102
103def f_and(x, y):
104    """x and y"""
105    return np.bitwise_and(x, y)
106
107
108def f_or(x, y):
109    """x or y"""
110    return np.bitwise_or(x, y)
111
112
113def f_not(x):
114    """not x"""
115    return np.logical_not(x).astype(int)
116
117
118def f_if_then_else(test, dit, dif):
119    """if test return dit else return dif"""
120    return np.where(test, dit, dif)
121
122
123
124full_function_set = [f_add, f_sub, f_mul, f_div, f_sqrt, f_log, f_abs, f_neg, f_inv, f_max, f_min, f_sin, f_cos, f_tan,
125                     f_iflte0, f_ifgt0, f_iflte, f_ifgt, f_add, f_or, f_not, f_if_then_else]