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May 7, 2016 19:00
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import numpy as np | |
from random import randint | |
from decimal import Decimal | |
from math import log10, floor | |
def floats_5(N): | |
""" | |
Generate random floats between a random range, where all floats | |
end with a '5'. | |
""" | |
# rang = randint(1, 1) | |
flts = np.random.uniform(0., 1., N) | |
# Add '5' to the end of each random float, with different lengths. | |
fl_5 = [] | |
for f in flts: | |
# Trim float. | |
i = randint(2, len(str(f).split('.')[1])) | |
# Create trimmed float that ends with a '5' . | |
f = Decimal(str(f).split('.')[0] + '.' + str(f).split('.')[1][:i] + | |
'5') | |
fl_5.append(f) | |
return fl_5 | |
def format_e(x): | |
""" | |
Taken from: http://stackoverflow.com/a/6913576/1391441 | |
""" | |
a = '%E' % x | |
return a.split('E')[0].rstrip('0').rstrip('.') + 'E' + a.split('E')[1] | |
def format_5(f, n): | |
""" | |
Round floats that end with a '5' correctly, bypassing Python's issue | |
with the round() function. | |
See: http://codereview.stackexchange.com/q/122243/35351 | |
""" | |
# If the last digit is 5 or larger, round up. | |
if int(f[-1]) >= 5: | |
r_up_down = 'ROUND_UP' | |
else: | |
r_up_down = 'ROUND_DOWN' | |
return Decimal.quantize(Decimal(f), Decimal(f[:-n]), rounding=r_up_down) | |
def round_to_n(x, n=1): | |
""" | |
Round float to n significant figures. | |
>>> round_to_n(31.51) | |
30.0 | |
>>> round_to_n(1.532) | |
2.0 | |
>>> round_to_n(2156.23) | |
2000.0 | |
>>> round_to_n(156.53, 3) | |
157.0 | |
>>> round_to_n(0.00235, 4) | |
0.00235 | |
>>> round_to_n(0.66, 1) | |
0.7 | |
>>> round_to_n(0.075) | |
0.08 | |
>>> round_to_n(0.075, 2) | |
0.075 | |
""" | |
if x == 0.: | |
x_r = 0. | |
elif 0. < abs(x) < 1.: | |
# Count number of decimal places. | |
nx = len(str(x).split('.')[1]) | |
print 'n, nx:', n, nx | |
if n >= nx: | |
# Keep all decimals. | |
x_r = x | |
elif n < nx: | |
# Decimal part of the float. | |
f1 = str(x).split('.')[1] | |
# Number of significant digits in float. | |
nd = len(f1.lstrip('0')) | |
# Number of leading zeroes after the decimal dot. | |
n0 = len(f1) - nd | |
print 'n0, nd:', n0, nd | |
if n < nd: | |
# New float with no leading zeroes. | |
x1 = '0.' + f1.lstrip('0')[:n+1] | |
print 'x1:', x1 | |
# Round float. | |
x2 = format_5(x1, nd-(n+1)) | |
print 'x2:', x2 | |
if n0 > 0: | |
# Reconstruct float. | |
x_r = float('0.' + '0'*n0 + str(x2).split('.')[1]) | |
else: | |
x_r = float('0.' + str(x2).split('.')[1]) | |
else: | |
x_r = x | |
else: | |
pass | |
return x_r | |
for f in [0., 0.01354, 0.00015, 0.25, 0.0075]: # floats_5(10) | |
print 'float:', f | |
new_f = round_to_n(f, 1) | |
print 'new_f:', new_f, '\n' |
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