Imports name this capability’s declared dependencies, which fune builds next to it in your project; each one links to its page.
import math
from typing import List
from .agri_fertiliser_application_types import FertiliserPlan, NutrientAnalysis, NutrientSupply, NutrientTargets
from .math_round_div import round_div ← from math.round-div ^1.0.0 · built alongside by fune
from .math_round_float import round_float ← from math.round-float ^1.0.0 · built alongside by fune
NUTRIENTS = ("nitrogen", "phosphate", "potash")
def _tenths_of_percent(name: str, value: float) -> int:
if isinstance(value, bool) or not isinstance(value, (int, float)) or not math.isfinite(value) or value < 0 or value > 100:
raise ValueError("analysis %s must be a finite percentage from 0 to 100, received %r" % (name, value))
return int(round(round_float(float(value), 1) * 10))
def fertiliser_application(analysis: NutrientAnalysis, targets: NutrientTargets, area_hectares: float) -> FertiliserPlan:
"""Product rate for a fertiliser, set by the limiting nutrient.
For each targeted nutrient the product needed is target / analysis; the
rate is the smallest of those, so no nutrient is applied beyond its target,
and the others show as a shortfall. The arithmetic is exact in tenths (of a
percent and of a kilogram) and the rate is rounded once, half up.
"""
a = [_tenths_of_percent(n, getattr(analysis, n)) for n in NUTRIENTS]
if sum(a) > 1000:
raise ValueError("analysis must not total more than 100%")
t: List[int] = []
for n in NUTRIENTS:
v = getattr(targets, n)
if isinstance(v, bool) or not isinstance(v, int) or v < 0 or v > 1000:
raise ValueError("target %s must be a whole number of kg/ha from 0 to 1000, received %r" % (n, v))
t.append(v)
if (
isinstance(area_hectares, bool)
or not isinstance(area_hectares, (int, float))
or not math.isfinite(area_hectares)
or area_hectares <= 0
or area_hectares > 10000
):
raise ValueError("areaHectares must be a finite number greater than 0 and at most 10000, received %r" % (area_hectares,))
area = int(round(round_float(float(area_hectares), 4) * 10000))
if area < 1:
raise ValueError("areaHectares must be at least 0.0001 hectares, received %r" % (area_hectares,))
if sum(t) == 0:
raise ValueError("at least one target must be above zero")
# Least product: target_i / a_i smallest, compared by cross-multiplying.
limit = -1
for i in range(3):
if t[i] == 0 or a[i] == 0:
continue
if limit < 0 or t[i] * a[limit] < t[limit] * a[i]:
limit = i
if limit < 0:
raise ValueError("the product contains none of the targeted nutrients")
# kg/ha in tenths = target x 100 / (a / 10) x 10.
rate = round_div(t[limit] * 10000, a[limit], "half-up")
s = [round_div(rate * ai, 1000, "half-up") for ai in a]
return FertiliserPlan(
limiting_nutrient=NUTRIENTS[limit],
product_kg_per_hectare=rate / 10,
total_product_kg=round_div(rate * area, 10000, "half-up") / 10,
supplied=NutrientSupply(nitrogen=s[0] / 10, phosphate=s[1] / 10, potash=s[2] / 10),
balance=NutrientSupply(
nitrogen=(s[0] - t[0] * 10) / 10,
phosphate=(s[1] - t[1] * 10) / 10,
potash=(s[2] - t[2] * 10) / 10,
),
)