bmi_calculator.py•10.8 kB
"""
BMI (Body Mass Index) Calculator
"""
from typing import Dict, Any
from medcalc import (
BaseCalculator,
CalculatorInfo,
Parameter,
ParameterType,
ValidationResult,
CalculationResult,
register_calculator
)
from medcalc.utils import round_number, UnitConverter
@register_calculator("bmi")
class BMICalculator(BaseCalculator):
"""BMI计算器实现"""
def get_info(self) -> CalculatorInfo:
return CalculatorInfo(
id=6,
name="Body Mass Index (BMI)",
category="anthropometry",
description="Calculate BMI from height and weight with unit conversion support",
parameters=[
Parameter(
name="height",
type=ParameterType.NUMERIC,
required=True,
unit="cm",
min_value=30,
max_value=300,
description="Height in centimeters"
),
Parameter(
name="weight",
type=ParameterType.NUMERIC,
required=True,
unit="kg",
min_value=1,
max_value=500,
description="Weight in kilograms"
),
Parameter(
name="height_unit",
type=ParameterType.CHOICE,
required=False,
default="cm",
choices=["cm", "m", "in", "ft"],
description="Unit for height"
),
Parameter(
name="weight_unit",
type=ParameterType.CHOICE,
required=False,
default="kg",
choices=["kg", "g", "lb", "lbs", "oz"],
description="Unit for weight"
)
],
references=[
"WHO. Obesity: preventing and managing the global epidemic. 2000."
]
)
def _parse_parameter(self, value: Any) -> tuple[float, str]:
"""解析参数，支持字符串格式如 '175cm' 或 '70kg'"""
if isinstance(value, (int, float)):
return float(value), ""
if isinstance(value, str):
import re
# 匹配数字和单位
match = re.match(r'^([0-9]*\.?[0-9]+)\s*([a-zA-Z]*)$', value.strip())
if match:
num_str, unit = match.groups()
return float(num_str), unit.lower()
# 处理英制高度格式如 "5ft 9in"
ft_in_match = re.match(r'^([0-9]+)\s*ft\s*([0-9]+)\s*in$', value.strip())
if ft_in_match:
feet, inches = ft_in_match.groups()
total_inches = int(feet) * 12 + int(inches)
return float(total_inches), "in"
raise ValueError(f"Cannot parse parameter value: {value}")
def validate_parameters(self, params: Dict[str, Any]) -> ValidationResult:
errors = []
warnings = []
# 获取参数定义
param_defs = {p.name: p for p in self.get_info().parameters}
# 检查必需参数
for param_name, param_def in param_defs.items():
if param_def.required and param_name not in params:
errors.append(f"Missing required parameter: {param_name}")
if errors:
return ValidationResult(is_valid=False, errors=errors)
# 验证数值范围（考虑单位转换）
for param_name in ["height", "weight"]:
if param_name in params:
try:
value, unit = self._parse_parameter(params[param_name])
except ValueError as e:
errors.append(f"Invalid {param_name} format: {e}")
continue
# 获取单位并转换为标准单位进行验证
converter = UnitConverter()
if param_name == "height":
height_unit = unit or params.get("height_unit", "cm")
try:
# 转换为厘米进行验证
height_cm = converter.convert(value, height_unit, "cm")
if height_cm < 30 or height_cm > 300:
errors.append(f"Height {value} {height_unit} is outside valid range (30-300 cm)")
except ValueError as e:
errors.append(f"Invalid height unit: {height_unit}")
elif param_name == "weight":
weight_unit = unit or params.get("weight_unit", "kg")
try:
# 转换为千克进行验证
weight_kg = converter.convert(value, weight_unit, "kg")
if weight_kg < 1 or weight_kg > 500:
errors.append(f"Weight {value} {weight_unit} is outside valid range (1-500 kg)")
# 添加警告（使用转换后的数值）
if weight_kg > 200:
warnings.append("Weight is very high, please verify")
except ValueError as e:
errors.append(f"Invalid weight unit: {weight_unit}")
return ValidationResult(
is_valid=len(errors) == 0,
errors=errors,
warnings=warnings
)
def calculate(self, params: Dict[str, Any]) -> CalculationResult:
# 解析参数值
height_value, height_unit_parsed = self._parse_parameter(params["height"])
weight_value, weight_unit_parsed = self._parse_parameter(params["weight"])
# 确定单位（优先使用解析出的单位）
height_unit = height_unit_parsed or params.get("height_unit", "cm")
weight_unit = weight_unit_parsed or params.get("weight_unit", "kg")
# 单位转换到标准单位（米和千克）
converter = UnitConverter()
height_m = converter.convert(height_value, height_unit, "m")
weight_kg = converter.convert(weight_value, weight_unit, "kg")
# 保存原始数值用于显示
height = height_value
weight = weight_value
# 计算BMI
bmi = weight_kg / (height_m * height_m)
bmi = round(bmi, 1) # 使用标准的 round 函数
# 确定分类
category = self._get_category(bmi)
# 生成详细解释（基于原有逻辑）
explanation = self._generate_explanation(
height, height_unit, height_m,
weight, weight_unit, weight_kg,
bmi, category
)
return CalculationResult(
value=bmi,
unit="kg/m^2",
explanation=explanation,
metadata={
"category": category,
"height_m": height_m,
"weight_kg": weight_kg,
"original_height": height,
"original_weight": weight,
"height_unit": height_unit,
"weight_unit": weight_unit
},
warnings=[]
)
def _get_category(self, bmi: float) -> str:
"""根据BMI值确定分类"""
if bmi < 18.5:
return "Underweight"
elif bmi < 25:
return "Normal weight"
elif bmi < 30:
return "Overweight"
else:
return "Obese"
def _generate_explanation(self, height: float, height_unit: str, height_m: float,
weight: float, weight_unit: str, weight_kg: float,
bmi: float, category: str) -> str:
"""生成详细的计算解释（基于原有逻辑）"""
explanation = "The formula for computing the patient's BMI is (weight)/(height * height), where weight is the patient's weight in kg and height is the patient's height in m.\n\n"
# 高度转换解释
height_explanation = self._get_height_explanation(height, height_unit, height_m)
explanation += height_explanation
# 重量转换解释
weight_explanation = self._get_weight_explanation(weight, weight_unit, weight_kg)
explanation += weight_explanation
# BMI计算
weight_kg_rounded = round(weight_kg, 1)
height_m_rounded = round(height_m, 2)
explanation += f"The patient's BMI is therefore {weight_kg_rounded} kg / ({height_m_rounded} m * {height_m_rounded} m) = {bmi} kg/m^2.\n\n"
# 分类信息
explanation += f"Category: {category}\n\n"
explanation += "BMI Categories:\n"
explanation += "- < 18.5: Underweight\n"
explanation += "- 18.5-24.9: Normal weight\n"
explanation += "- 25.0-29.9: Overweight\n"
explanation += "- ≥ 30.0: Obese"
return explanation
def _get_height_explanation(self, height: float, height_unit: str, height_m: float) -> str:
"""生成高度转换解释"""
height_m_rounded = round(height_m, 3)
if height_unit == "m":
return f"The patient's height is {height} m.\n"
elif height_unit == "cm":
return f"The patient's height is {height} cm, which is {height} cm * 1 m / 100 cm = {height_m_rounded} m.\n"
elif height_unit == "ft":
return f"The patient's height is {height} ft, which is {height} ft * 0.3048 m / ft = {height_m_rounded} m.\n"
elif height_unit == "in":
return f"The patient's height is {height} in, which is {height} in * 0.0254 m / in = {height_m_rounded} m.\n"
else:
return f"The patient's height is {height} {height_unit}, converted to {height_m_rounded} m.\n"
def _get_weight_explanation(self, weight: float, weight_unit: str, weight_kg: float) -> str:
"""生成重量转换解释"""
weight_kg_rounded = round(weight_kg, 3)
if weight_unit == "kg":
return f"The patient's weight is {weight} kg.\n"
elif weight_unit in ["lb", "lbs"]:
return f"The patient's weight is {weight} lbs so this converts to {weight} lbs * 0.453592 kg/lbs = {weight_kg_rounded} kg.\n"
elif weight_unit == "g":
return f"The patient's weight is {weight} g so this converts to {weight} g * 1 kg/1000 g = {weight_kg_rounded} kg.\n"
else:
return f"The patient's weight is {weight} {weight_unit}, converted to {weight_kg_rounded} kg.\n"