marceloneppel · October 25, 2025 18:53 · Oct 21, 2023
diff --git a/str_float.py b/str_float.py
@@ -0,0 +1,127 @@
+import numba 
+import numpy as np
+import numba
+from numba import types, jit,njit, generated_jit
+from numba import deferred_type, optional
+from numba import void,b1,u1,u2,u4,u8,i1,i2,i4,i8,f4,f8,c8,c16
+from numba.typed import List, Dict
+from numba.types import ListType, unicode_type, UnicodeType
+from numba.cpython.unicode import _empty_string, _set_code_point, _get_code_point, PY_UNICODE_1BYTE_KIND
+from numba.extending import overload, overload_method
+
+DIGITS_START = 48
+DIGITS_END = 58
+DASH = 45
+DOT = 46
+PLUS = 43
+E_CHAR = 101
+
+@njit(cache=True)
+def get_n_digits(x):
+    l1,l2 = 0,-1
+    _x = x
+    while _x > 0:
+        _x = _x // 10
+        l1 += 1
+
+    _x = x % 10     
+    while _x > 1e-10:
+        _x = (_x * 10) % 10
+        l2 += 1
+        if(l2 >= 16): break
+    return l1, l2
+
+@njit
+def float_to_str(x):
+    if(x == np.inf):
+        return 'inf'
+    elif(x == -np.inf):
+        return '-inf'
+
+    isneg = int(x < 0.0)
+    x = np.abs(x)
+
+    if(x != 0.0):
+        # There is probably a more efficient way to do this
+        e = np.floor(np.log10(x))
+        if(10**e - x > 0): e -= 1
+    else:
+        e = 0
+
+    is_exp, is_neg_exp = e >= 16, e <= -16
+
+    exp_chars = 0
+    if (is_exp or is_neg_exp):
+        exp_chars = 4
+        if(e >= 100 or e <= -100): exp_chars = 5
+
+
+    if(is_exp):
+        offset_x = np.around(x * (10.0**-(e)),15)
+        l1, l2 = get_n_digits(offset_x)
+    elif(is_neg_exp):
+        offset_x = np.around(x * (10**-(e)),15)
+        l1, l2 = get_n_digits(offset_x)
+    else:
+        offset_x = x
+        l1,l2 = get_n_digits(x)
+        l2 = max(1,l2) # Will have at least .0 
+
+    use_dec = l2 > 0
+
+    # print("<<", e, offset_x, l2)
+
+    l = l1+l2+use_dec
+    length = l+isneg+exp_chars
+    s = _empty_string(PY_UNICODE_1BYTE_KIND,length)
+    if(isneg): _set_code_point(s,0,DASH)
+
+    _x = offset_x
+    for i in range(l1):
+        digit = int(_x % 10)
+        _set_code_point(s,(isneg+l1)-i-1,digit + DIGITS_START)
+        _x = _x // 10
+
+    if(use_dec):
+        _set_code_point(s,l1+isneg,DOT)
+
+    _x = offset_x % 10
+    for i in range(l2):
+        _x = (_x * 10) % 10
+        digit = int(_x)  
+
+        _set_code_point(s,(isneg+l1)+i+use_dec,digit + DIGITS_START)
+
+    if(is_exp or is_neg_exp):
+        i = (isneg+l1+use_dec+l2)
+        _set_code_point(s,i,E_CHAR)        
+        if(is_exp):
+            _set_code_point(s,i+1,PLUS)     
+        if(is_neg_exp):
+            _set_code_point(s,i+1,DASH)           
+
+        i = length-1
+        exp = np.abs(e)
+        while(exp > 0):
+            digit = exp % 10
+            _set_code_point(s,i,digit + DIGITS_START)
+            exp = exp // 10
+            i -= 1
+
+    return s
+
+# Monkey Patch type conversions so that float(str) and str(float)
+# work like in normal python
+
+@overload_method(types.Float, '__str__')
+def overload_float_to_str(x):
+    def impl(x):
+        return float_to_str(x)
+    return impl
+
+@njit
+def test(x):
+    s = "This is the number: " + str(x)
+    return s
+
+print(test(-1.9))