improve float_to_rational method

Author: OSkrk

shared/utils.py

@@ -25,33 +25,42 @@ def rational_to_float(value) -> float:
 
 
 def float_to_rational(value: float):
-    """Casts a float to a DcRationalNumberType.
+    """Casts a float to a RationalNumberType.
 
     :param value: The value to cast.
-    :return: DcRationalNumberType -- the cast result.
+    :return: tuple  with value and exponent-- the cast result.
     """
-    if value == 0:
-        return 0, 0
-    string = format(value, ".2e")
-    if abs(value) < 1:
-        string = string.split("e")  # Keep the sign
+    sign = ""
+    if value < 0:
+        sign = "-"
+    exp = 0
+    string = format(value, ".3f")  # Keep three decimal places
+    elements = string.split(".")
+    val = elements[0]
+    decimal = elements[1]
+
+    if abs(value) < 1:  # decimal number
+        val = sign + decimal
+        exp = -3
     else:
-        string = string.split("e+")
-    try:
-        value = int(string[0])
-        exponent = int(string[1])
-    except ValueError:
-        value = int(string[0].replace('.', ''))
-        exponent = int(string[1]) - 2
-    return value, exponent
+        while abs(int(val)) > 32767:
+            val = str(round(int(val) / 10))
+            exp += 1
+        if int(decimal) != 0:
+            while abs(int(val)) <= 3000:
+                val = val + decimal[0]
+                decimal = decimal[1:]
+                exp -= 1
+                if decimal == '':
+                    break
+    return int(val), int(exp)
 
 
 def float_to_dc_rational(input: float) -> DcRationalNumberType:
     value, exponent = float_to_rational(input)
     return DcRationalNumberType(exponent, value)
 
 
-
 def greater_rational(rational_1, rational_2):
     """Compares two RationalNumberType.
 

tests/__init__.py

@@ -0,0 +1,129 @@
+from shared.utils import float_to_rational
+import pytest
+
+
+# Positive values :
+def test_float_to_rational_003() -> None:
+    output = float_to_rational(0.003)
+    assert output[0] == 3 and output[1] == -3
+
+
+def test_float_to_rational_021() -> None:
+    output = float_to_rational(0.021)
+    assert output[0] == 21 and output[1] == -3
+
+
+def test_float_to_rational_0321() -> None:
+    output = float_to_rational(0.321)
+    assert output[0] == 321 and output[1] == -3
+
+
+def test_float_to_rational_1() -> None:
+    output = float_to_rational(1)
+    assert output[0] == 1 and output[1] == 0
+
+
+def test_float_to_rational_1_3888888888888888() -> None:
+    output = float_to_rational(1.3888888888888888)
+    assert output[0] == 1389 and output[1] == -3
+
+
+def test_float_to_rational_12() -> None:
+    output = float_to_rational(12)
+    assert output[0] == 12 and output[1] == 0
+
+def test_float_to_rational_99_999() -> None:
+    output = float_to_rational(99.999)
+    assert output[0] == 9999 and output[1] == -2
+
+
+def test_float_to_rational_123() -> None:
+    output = float_to_rational(123)
+    assert output[0] == 123 and output[1] == 0
+
+def test_float_to_rational_12_201() -> None:
+    output = float_to_rational(12.201)
+    assert output[0] == 12201 and output[1] == -3
+
+def test_float_to_rational_123_201() -> None:
+    output = float_to_rational(123.201)
+    assert output[0] == 12320 and output[1] == -2
+
+
+def test_float_to_rational_3000() -> None:
+    output = float_to_rational(3000)
+    assert output[0] == 3000 and output[1] == 0
+
+
+def test_float_to_rational_32769() -> None:
+    output = float_to_rational(32769)
+    assert output[0] == 3277 and output[1] == 1
+
+
+def test_float_to_rational_100000() -> None:
+    output = float_to_rational(100000)
+    assert output[0] == 10000 and output[1] == 1
+
+
+# Negative values :
+
+def test_float_to_rational_neg_003() -> None:
+    output = float_to_rational(-0.003)
+    assert output[0] == -3 and output[1] == -3
+
+
+def test_float_to_rational_neg_021() -> None:
+    output = float_to_rational(-0.021)
+    assert output[0] == -21 and output[1] == -3
+
+
+def test_float_to_rational_neg_0321() -> None:
+    output = float_to_rational(-0.321)
+    assert output[0] == -321 and output[1] == -3
+
+
+def test_float_to_rational_neg_1() -> None:
+    output = float_to_rational(-1)
+    assert output[0] == -1 and output[1] == 0
+
+
+def test_float_to_rational_neg_1_3888888888888888() -> None:
+    output = float_to_rational(-1.3888888888888888)
+    assert output[0] == -1389 and output[1] == -3
+
+
+def test_float_to_rational_neg_12() -> None:
+    output = float_to_rational(-12)
+    assert output[0] == -12 and output[1] == 0
+
+def test_float_to_rational_neg_99_999() -> None:
+    output = float_to_rational(-99.999)
+    assert output[0] == -9999 and output[1] == -2
+
+
+def test_float_to_rational_neg_123() -> None:
+    output = float_to_rational(-123)
+    assert output[0] == -123 and output[1] == 0
+
+def test_float_to_rational_neg_12_201() -> None:
+    output = float_to_rational(-12.201)
+    assert output[0] == -12201 and output[1] == -3
+
+def test_float_to_rational_neg_123_201() -> None:
+    output = float_to_rational(-123.201)
+    assert output[0] == -12320 and output[1] == -2
+
+
+def test_float_to_rational_neg_3000() -> None:
+    output = float_to_rational(-3000)
+    assert output[0] == -3000 and output[1] == 0
+
+
+def test_float_to_rational_32769() -> None:
+    output = float_to_rational(32769)
+    assert output[0] == 3277 and output[1] == 1
+
+
+def test_float_to_rational_100000() -> None:
+    output = float_to_rational(100000)
+    assert output[0] == 10000 and output[1] == 1