113 lines
4.3 KiB
Python
113 lines
4.3 KiB
Python
""" # lint-amnesty, pylint: disable=django-not-configured
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Standard resistor values.
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Commonly used for verifying electronic components in circuit classes are
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standard values, or conversely, for generating realistic component
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values in parameterized problems. For details, see:
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http://en.wikipedia.org/wiki/Electronic_color_code
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"""
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# pylint: disable=invalid-name
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# r is standard name for a resistor. We would like to use it as such.
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import math
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import numbers
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E6 = [10, 15, 22, 33, 47, 68]
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E12 = [10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82]
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E24 = [10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82, 11, 13, 16, 20,
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24, 30, 36, 43, 51, 62, 75, 91]
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E48 = [100, 121, 147, 178, 215, 261, 316, 383, 464, 562, 681, 825, 105,
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127, 154, 187, 226, 274, 332, 402, 487, 590, 715, 866, 110, 133,
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162, 196, 237, 287, 348, 422, 511, 619, 750, 909, 115, 140, 169,
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205, 249, 301, 365, 442, 536, 649, 787, 953]
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E96 = [100, 121, 147, 178, 215, 261, 316, 383, 464, 562, 681, 825, 102,
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124, 150, 182, 221, 267, 324, 392, 475, 576, 698, 845, 105, 127,
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154, 187, 226, 274, 332, 402, 487, 590, 715, 866, 107, 130, 158,
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191, 232, 280, 340, 412, 499, 604, 732, 887, 110, 133, 162, 196,
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237, 287, 348, 422, 511, 619, 750, 909, 113, 137, 165, 200, 243,
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294, 357, 432, 523, 634, 768, 931, 115, 140, 169, 205, 249, 301,
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365, 442, 536, 649, 787, 953, 118, 143, 174, 210, 255, 309, 374,
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453, 549, 665, 806, 976]
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E192 = [100, 121, 147, 178, 215, 261, 316, 383, 464, 562, 681, 825, 101,
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123, 149, 180, 218, 264, 320, 388, 470, 569, 690, 835, 102, 124,
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150, 182, 221, 267, 324, 392, 475, 576, 698, 845, 104, 126, 152,
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184, 223, 271, 328, 397, 481, 583, 706, 856, 105, 127, 154, 187,
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226, 274, 332, 402, 487, 590, 715, 866, 106, 129, 156, 189, 229,
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277, 336, 407, 493, 597, 723, 876, 107, 130, 158, 191, 232, 280,
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340, 412, 499, 604, 732, 887, 109, 132, 160, 193, 234, 284, 344,
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417, 505, 612, 741, 898, 110, 133, 162, 196, 237, 287, 348, 422,
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511, 619, 750, 909, 111, 135, 164, 198, 240, 291, 352, 427, 517,
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626, 759, 920, 113, 137, 165, 200, 243, 294, 357, 432, 523, 634,
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768, 931, 114, 138, 167, 203, 246, 298, 361, 437, 530, 642, 777,
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942, 115, 140, 169, 205, 249, 301, 365, 442, 536, 649, 787, 953,
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117, 142, 172, 208, 252, 305, 370, 448, 542, 657, 796, 965, 118,
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143, 174, 210, 255, 309, 374, 453, 549, 665, 806, 976, 120, 145,
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176, 213, 258, 312, 379, 459, 556, 673, 816, 988]
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def iseia(r, valid_types=(E6, E12, E24)):
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'''
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Check if a component is a valid EIA value.
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By default, check 5% component values
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'''
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# Step 1: Discount things which are not numbers
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if not isinstance(r, numbers.Number) or \
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r < 0 or \
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math.isnan(r) or \
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math.isinf(r):
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return False
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# Special case: 0 is an okay resistor
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if r == 0:
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return True
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# Step 2: Move into the range [100, 1000)
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while r < 100:
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r = r * 10
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while r >= 1000:
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r = r / 10
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# Step 3: Discount things which are not integers, and cast to int
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if abs(r - round(r)) > 0.01:
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return False
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r = int(round(r))
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# Step 4: Check if we're a valid EIA value
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for type_list in valid_types:
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if r in type_list:
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return True
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if int(r / 10.) in type_list and (r % 10) == 0:
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return True
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return False
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if __name__ == '__main__':
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# Test cases. All of these should return True
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print(iseia(100)) # 100 ohm resistor is EIA
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print(not iseia(101)) # 101 is not
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print(not iseia(100.3)) # Floating point close to EIA is not EIA
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print(iseia(100.001)) # But within floating point error is
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print(iseia(1e5)) # We handle big numbers well
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print(iseia(2200)) # We handle middle-of-the-list well
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# We can handle 1% components correctly; 2.2k is EIA24, but not EIA48.
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print(not iseia(2200, (E48, E96, E192)))
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print(iseia(5490e2, (E48, E96, E192)))
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print(iseia(2200))
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print(not iseia(5490e2))
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print(iseia(1e-5)) # We handle little numbers well
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print(not iseia("Hello")) # Junk handled okay
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print(not iseia(float('NaN')))
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print(not iseia(-1))
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print(not iseia(iseia))
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print(not iseia(float('Inf')))
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print(iseia(0)) # Corner case. 0 is a standard resistor value.
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