周数查询

复制from datetime import date, timedelta

# ISO 周数：date.isocalendar() 返回 (ISO year, ISO week, weekday)
d = date(2024, 12, 31)
iso_year, iso_week, _ = d.isocalendar()
print(f"{d} → ISO {iso_year}-W{iso_week:02d}")  # 2024-12-31 → ISO 2025-W01

# 美式周：1 月 1 日所在周为第 1 周，周日为周始
def us_week(d: date) -> int:
    jan1 = d.replace(month=1, day=1)
    # 计算 1 月 1 日是周几（周一=0 … 周日=6）
    jan1_wd = jan1.weekday()  # 周一=0
    # 美式周日=6 → 转成周日=0
    jan1_sun = (jan1_wd + 1) % 7
    # 该年第几天（1 月 1 日=1）
    day_of_year = d.timetuple().tm_yday
    # 偏移到周日起始
    offset = (day_of_year - 1) + jan1_sun
    return offset // 7 + 1

print(f"{d} → US Week {us_week(d)}")  # 2024-12-31 → US Week 53

# 自定义周起：指定周起始日（0=周一 … 6=周日）
def custom_week(d: date, start_wday: int = 0) -> int:
    jan1 = d.replace(month=1, day=1)
    jan1_wd = jan1.weekday()
    # 偏移使 start_wday 为 0
    offset = (jan1_wd - start_wday) % 7
    day_of_year = d.timetuple().tm_yday
    return (day_of_year - 1 + offset) // 7 + 1

print(f"{d} → Custom(周一始) Week {custom_week(d, 0)}")  # 53

复制package main

import (
	"fmt"
	"time"
)

func main() {
	d := time.Date(2024, 12, 31, 0, 0, 0, 0, time.UTC)

	// ISO 周数：Go 标准库 ISOWeek()
	year, week := d.ISOWeek()
	fmt.Printf("%s → ISO %d-W%02d\n", d.Format("2006-01-02"), year, week)
	// 2024-12-31 → ISO 2025-W01

	// 美式周：1 月 1 日所在周为第 1 周，周日为周始
	jan1 := time.Date(d.Year(), 1, 1, 0, 0, 0, 0, time.UTC)
	// 周日=0 … 周六=6
	jan1Weekday := int(jan1.Weekday()) // Go 中 Sunday=0
	dayOfYear := d.YearDay()
	usWeek := (dayOfYear-1+jan1Weekday)/7 + 1
	fmt.Printf("%s → US Week %d\n", d.Format("2006-01-02"), usWeek)
	// 2024-12-31 → US Week 53

	// 自定义周起：指定周起始日（0=周日 … 6=周六）
	startWday := 1 // 周一
	offset := (jan1Weekday - startWday + 7) % 7
	customWeek := (dayOfYear-1+offset)/7 + 1
	fmt.Printf("%s → Custom(周一始) Week %d\n", d.Format("2006-01-02"), customWeek)
	// 2024-12-31 → Custom Week 53
}

复制// ISO 周数：使用 Date 的 getISOWeek 扩展（需手动计算）
function isoWeek(date) {
  const d = new Date(date);
  d.setHours(0, 0, 0, 0);
  // 周四所在周为 ISO 周
  d.setDate(d.getDate() + 3 - ((d.getDay() + 6) % 7));
  const jan1 = new Date(d.getFullYear(), 0, 1);
  const diff = (d - jan1) / 86400000;
  return Math.ceil((diff + jan1.getDay() + 1) / 7);
}

const d = new Date('2024-12-31');
console.log(`ISO Week: ${isoWeek(d)}`); // 1

// 美式周：1 月 1 日所在周为第 1 周，周日为周始
function usWeek(date) {
  const d = new Date(date);
  const jan1 = new Date(d.getFullYear(), 0, 1);
  const jan1Day = jan1.getDay(); // 0=周日
  const dayOfYear = Math.floor((d - jan1) / 86400000) + 1;
  return Math.floor((dayOfYear - 1 + jan1Day) / 7) + 1;
}

console.log(`US Week: ${usWeek(d)}`); // 53

// 自定义周起：指定周起始日（0=周日 … 6=周六）
function customWeek(date, startDay = 0) {
  const d = new Date(date);
  const jan1 = new Date(d.getFullYear(), 0, 1);
  const jan1Day = jan1.getDay();
  const offset = (jan1Day - startDay + 7) % 7;
  const dayOfYear = Math.floor((d - jan1) / 86400000) + 1;
  return Math.floor((dayOfYear - 1 + offset) / 7) + 1;
}

console.log(`Custom(周日始) Week: ${customWeek(d, 0)}`); // 53
console.log(`Custom(周一始) Week: ${customWeek(d, 1)}`); // 53