piker/piker/calc.py

50 lines
1.6 KiB
Python

# piker: trading gear for hackers
# Copyright (C) 2018-present Tyler Goodlet (in stewardship of piker0)
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
"""
Handy financial calculations.
"""
import math
import itertools
def humanize(number, digits=1):
"""Convert large numbers to something with at most 3 digits and
a letter suffix (eg. k: thousand, M: million, B: billion).
"""
try:
float(number)
except ValueError:
return 0
if not number or number <= 0:
return number
mag2suffix = {3: 'k', 6: 'M', 9: 'B'}
mag = math.floor(math.log(number, 10))
if mag < 3:
return number
maxmag = max(itertools.takewhile(lambda key: mag >= key, mag2suffix))
return "{:.{digits}f}{}".format(
number/10**maxmag, mag2suffix[maxmag], digits=digits)
def percent_change(init, new):
"""Calcuate the percentage change of some ``new`` value
from some initial value, ``init``.
"""
if not (init and new):
return 0
return (new - init) / init * 100.