# Star placement (/en/docs/go/star) Where a group of stars lands given birth data. Use this layer when you do not want a whole chart and only need "which palace does Lucun land in?" or "how are the adjective stars distributed on this chart?". Every index is a **palace index**: 0 is the Yin palace, 11 the Chou palace. ## StarBirth [#starbirth] The entry points that take birth data all share this one parameter struct. ```go type StarBirth struct { SolarDate string TimeIndex uint8 Gender string FixLeap bool Language string Config *Config FromStem string FromBranch string } ``` | Field | Type | Description | | ------------------------- | --------- | ------------------------------------------------------------------------- | | `SolarDate` | `string` | Solar date in `YYYY-M-D` | | `TimeIndex` | `uint8` | Hour index 0–12 | | `Gender` | `string` | Gender, which sets the direction of the Changsheng and Boshi gods | | `FixLeap` | `bool` | Whether to correct for leap months | | `Language` | `string` | Output language for star names; empty takes `zh-CN` | | `Config` | `*Config` | Charting configuration; `nil` takes the defaults | | `FromStem` / `FromBranch` | `string` | The pillar anchoring the five elements class; both must be given together | ```go birth := iztro.StarBirth{ SolarDate: "2000-8-16", TimeIndex: 2, Gender: iztro.GenderFemale, FixLeap: true, Language: "en-US", } ``` The examples on this page set `Language` to `"en-US"`, so the star names in the output are English. Leaving the field empty would take the default of `zh-CN`. Once both are given, the class is derived from that pillar instead, which in turn moves Ziwei and Tianfu and the Changsheng gods. How the other star groups are placed is unaffected. Use it to obtain the placements of the Zhongzhou school's earth and human charts. *** ## GetStartIndex [#getstartindex] **Purpose** Find the starting palaces of Ziwei and Tianfu. **Zi Wei meaning** Ziwei is the anchor of the whole chart, located from the five elements class and the lunar day by the Ziwei placement rule; the other thirteen major stars then spread out from Ziwei and Tianfu. Tianfu's position mirrors Ziwei's. **Signature** ```go func GetStartIndex(birth StarBirth) (StartIndex, error) ``` **Return value** `StartIndex{ ZiweiIndex, TianfuIndex int }`. **Example** ```go s, _ := iztro.GetStartIndex(birth) fmt.Printf("%+v\n", s) ``` **Output** ```text {ZiweiIndex:4 TianfuIndex:8} ``` *** ## Landing indices per group [#landing-indices-per-group] The following six entry points share a shape: they take a `StarBirth` and return a struct whose fields are all palace indices. | Function | Return type | Fields | Placement rule | | --------------------- | ------------------ | ------------------------------------------ | ---------------------------------------------------------------------------------------------- | | `GetLuYangTuoMaIndex` | `LuYangTuoMaIndex` | `LuIndex` `YangIndex` `TuoIndex` `MaIndex` | The year stem places Lucun, with Qingyang ahead and Tuoluo behind; Tianma from the year branch | | `GetKuiYueIndex` | `KuiYueIndex` | `KuiIndex` `YueIndex` | Year stem | | `GetChangQuIndex` | `ChangQuIndex` | `ChangIndex` `QuIndex` | Hour branch | | `GetKongJieIndex` | `KongJieIndex` | `KongIndex` `JieIndex` | Hour branch | | `GetTimelyStarIndex` | `TimelyStarIndex` | `TaifuIndex` `FenggaoIndex` | Hour branch | | `GetLuanXiIndex` | `LuanXiIndex` | `HongluanIndex` `TianxiIndex` | Year branch | **Example** ```go l, _ := iztro.GetLuYangTuoMaIndex(birth) c, _ := iztro.GetChangQuIndex(birth) lx, _ := iztro.GetLuanXiIndex(birth) fmt.Printf("%+v\n%+v %+v\n", l, c, lx) ``` **Output** ```text {LuIndex:6 YangIndex:7 TuoIndex:5 MaIndex:0} {ChangIndex:6 QuIndex:4} {HongluanIndex:9 TianxiIndex:3} ``` Qingyang sits one palace ahead of Lucun and Tuoluo one behind — the direct expression of the mnemonic "Qingyang before Lucun, Tuoluo after". *** ## GetDailyStarIndex / GetMonthlyStarIndex / GetYearlyStarIndex [#getdailystarindex--getmonthlystarindex--getyearlystarindex] **Purpose** Get the landing palaces of the adjective stars placed by day, month and year. **Zi Wei meaning** Adjective stars are grouped by how they are placed: day-based stars count forward from a minor star's position, starting at day one, to the birth day; month-based stars are located from the lunar month; year-based stars are the largest group and start from the year stem or year branch. **Return value** | Function | Return type | Fields | | --------------------- | ------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `GetDailyStarIndex` | `DailyStarIndex` | `SantaiIndex` `BazuoIndex` `EnguangIndex` `TianguiIndex` | | `GetMonthlyStarIndex` | `MonthlyStarIndex` | `YuejieIndex` `TianyaoIndex` `TianxingIndex` `YinshaIndex` `TianyueIndex` `TianwuIndex` | | `GetYearlyStarIndex` | `YearlyStarIndex` | 27 fields: `XianchiIndex` `HuagaiIndex` `GuchenIndex` `GuasuIndex` `TiancaiIndex` `TianshouIndex` `TianchuIndex` `PosuiIndex` `FeilianIndex` `LongchiIndex` `FenggeIndex` `TiankuIndex` `TianxuIndex` `TianguanIndex` `TianfuIndex` `TiandeIndex` `YuedeIndex` `TiankongIndex` `JieluIndex` `KongwangIndex` `XunkongIndex` `TianshangIndex` `TianshiIndex` `JiekongIndex` `JieshaAdjIndex` `NianjieIndex` `DahaoAdjIndex` | **Example** ```go d, _ := iztro.GetDailyStarIndex(birth) m, _ := iztro.GetMonthlyStarIndex(birth) fmt.Printf("%+v\n%+v\n", d, m) ``` **Output** ```text {SantaiIndex:0 BazuoIndex:10 EnguangIndex:9 TianguiIndex:7} {YuejieIndex:0 TianyaoIndex:5 TianxingIndex:1 YinshaIndex:0 TianyueIndex:9 TianwuIndex:0} ``` **Edge cases and pitfalls** Year-based adjective stars belong to the yearly spirits, so their year branch comes from `HoroscopeDivide` rather than `YearDivide`. When the two settings differ, year-based stars and the major and minor stars can rest on different year branches — a deliberate distinction of school. They are year-based too, but `GetLuanXiIndex` gives them separately. These three only enter the chart when `Algorithm` is the Zhongzhou school, replacing the default placement of Jielu, Kongwang and Dahao; under the default school they are still computed, just never placed in a palace. *** ## GetMajorStar / GetMinorStar / GetAdjectiveStar [#getmajorstar--getminorstar--getadjectivestar] **Purpose** Get the complete distribution of major, minor and adjective stars across the twelve palaces. **Signature** ```go func GetMajorStar(birth StarBirth) ([][]Star, error) func GetMinorStar(birth StarBirth) ([][]Star, error) func GetAdjectiveStar(birth StarBirth) ([][]Star, error) ``` **Return value** A slice of twelve, indexed by palace index. Each item is that palace's slice of `Star`s, possibly empty. **Example** ```go major, _ := iztro.GetMajorStar(birth) for i := 0; i < 5; i++ { names := []string{} for _, s := range major[i] { names = append(names, s.Name) } fmt.Println(i, names) } ``` **Output** ```text 0 [general minister] 1 [sun sage] 2 [marshal] 3 [advisor] 4 [emperor] ``` **Edge cases and pitfalls** The returned `Star`s carry brightness and natal mutagen marks and are identical to those from a full chart — they go through the same code. If you want the whole chart, `BySolar` is simpler. Note the naming across languages: Go and Python use the singular (`GetMajorStar`, `get_major_star`) where Rust uses the plural (`get_major_stars`); the behaviour is the same. *** ## GetChangsheng12 / GetBoShi12 / GetYearly12 [#getchangsheng12--getboshi12--getyearly12] **Purpose** Get how the four groups of twelve gods are arranged across the twelve palaces. **Zi Wei meaning** Each group is twelve marks filling the twelve palaces, exactly one per palace: the Changsheng gods start from the five elements class with direction from gender and year-branch polarity; the Boshi gods start from Lucun with the same direction rule; the Sui-qian gods run forward from the year branch, and the Jiang-qian gods start from the trine group of the year branch. **Signature** ```go func GetChangsheng12(birth StarBirth) ([]string, error) func GetBoShi12(birth StarBirth) ([]string, error) func GetYearly12(birth StarBirth) (Yearly12, error) ``` **Return value** A slice of twelve keys, indexed by palace index. `GetYearly12` returns `Yearly12{ Suiqian12, Jiangqian12 []string }`. **Example** ```go cs, _ := iztro.GetChangsheng12(birth) bs, _ := iztro.GetBoShi12(birth) y, _ := iztro.GetYearly12(birth) fmt.Println(cs[:4]) fmt.Println(bs[:4]) fmt.Println(y.Suiqian12[:4]) fmt.Println(y.Jiangqian12[:4]) ``` **Output** ```text [jue mu si bing] [faylian zhoushu jiangjun xiaohao] [diaoke bingfu suijian huiqi] [suiyi xiishen huagai jiesha] ``` These are keys rather than translated names; use `Translate(key, language)` to display them. *** ## GetChangsheng12StartIndex / GetJiangqian12StartIndex [#getchangsheng12startindex--getjiangqian12startindex] **Purpose** Get just the starting palace of two of the god groups, without laying out the whole cycle. **Zi Wei meaning** The Changsheng starting point is set by the five elements class: water 2nd starts at Shen, wood 3rd at Hai, metal 4th at Si, earth 5th at Shen, fire 6th at Yin. The Jiangxing starting point is set by the trine group of the year branch: yin/woo/xu years at Woo, shen/zi/chen years at Zi, si/you/chou years at You, hai/mao/wei years at Mao. **Signature** ```go func GetChangsheng12StartIndex(fiveElementsClass string) (int, error) func GetJiangqian12StartIndex(branchKey string) (int, error) ``` **Return value** `int`, 0–11. Neither function needs birth data. **Example** ```go a, _ := iztro.GetChangsheng12StartIndex(iztro.ClassWater2nd) b, _ := iztro.GetChangsheng12StartIndex(iztro.ClassFire6th) c, _ := iztro.GetJiangqian12StartIndex(iztro.BranchZi) d, _ := iztro.GetJiangqian12StartIndex(iztro.BranchWu) fmt.Println(a, b, c, d) ``` **Output** ```text 6 0 10 4 ``` Water 2nd puts Changsheng in Shen (index 6), fire 6th in Yin (index 0). *** ## GetHoroscopeStar [#gethoroscopestar] **Purpose** Get the scope-star distribution of a horoscope layer. **Zi Wei meaning** Scope stars are the ten stars a horoscope produces: Tiankui, Tianyue, Wenchang, Wenqu, Lucun, Qingyang, Tuoluo, Tianma, Hongluan and Tianxi. Where they land is fixed by that layer's stem and branch, and their names change with the layer. The yearly layer carries one extra star, Nianjie. **Signature** ```go func GetHoroscopeStar(stemKey, branchKey, scope string, language Language) ([][]Star, error) ``` **Parameters** | Parameter | Type | Required | Default | Description | | ----------- | ---------- | -------- | ------- | ----------------------------------------------- | | `stemKey` | `string` | Yes | — | Stem key of that layer | | `branchKey` | `string` | Yes | — | Branch key of that layer | | `scope` | `string` | Yes | — | The horoscope layer, which fixes the star names | | `language` | `Language` | Yes | — | Chart language | **Return value** A slice of twelve, indexed by palace index. **Star names per layer** | Natal | Decadal | Yearly | Monthly | Daily | Hourly | | -------- | -------- | -------- | -------- | ------- | -------- | | Tiankui | Yunkui | Liukui | Yuekui | Rikui | Shikui | | Tianyue | Yunyue | Liuyue | Yueyue | Riyue | Shiyue | | Wenchang | Yunchang | Liuchang | Yuechang | Richang | Shichang | | Wenqu | Yunqu | Liuqu | Yuequ | Riqu | Shiqu | | Lucun | Yunlu | Liulu | Yuelu | Rilu | Shilu | | Qingyang | Yunyang | Liuyang | Yueyang | Riyang | Shiyang | | Tuoluo | Yuntuo | Liutuo | Yuetuo | Rituo | Shituo | | Tianma | Yunma | Liuma | Yuema | Rima | Shima | | Hongluan | Yunluan | Liuluan | Yueluan | Riluan | Shiluan | | Tianxi | Yunxi | Liuxi | Yuexi | Rixi | Shixi | The keys take the form `yunlu` (decadal Lucun), `liulu` (yearly), `yuelu` (monthly), `rilu` (daily), `shilu` (hourly). **Example** ```go decadal, _ := iztro.GetHoroscopeStar(iztro.StemJia, iztro.BranchZi, iztro.ScopeDecadal, iztro.LanguageEnUS) for i := 0; i < 4; i++ { names := []string{} for _, s := range decadal[i] { names = append(names, s.Name) } fmt.Println(i, names) } ``` **Output** ```text 0 [money(D) horse(D)] 1 [driven(D) attractive(D)] 2 [] 3 [scholar(D)] ``` **Edge cases and pitfalls** The result for `ScopeYearly` additionally contains Nianjie, located from the yearly branch and placed ahead of the ten scope stars. No other layer has it. *** ## Low-level placement [#low-level-placement] The functions above all start from birth data, deriving the year pillar, the Soul palace and the corrected lunar month internally before placing anything. This group takes those intermediates directly and is reusable in a pipeline of your own. | Function | Takes | Returns (every field a palace index `int`) | | ---------------------------------------------------------------- | -------------------------------------- | ----------------------------------------------------- | | `GetZuoYouIndex(lunarMonth)` | The corrected lunar month, 1–12 | `ZuoYouIndex{ZuoIndex, YouIndex}` | | `GetHuoLingIndex(branchKey, timeIndex)` | Year branch, hour | `HuoLingIndex{HuoIndex, LingIndex}` | | `GetHuagaiXianchiIndex(branchKey)` | Year branch | `HuagaiXianchiIndex{HuagaiIndex, XianchiIndex}` | | `GetGuGuaIndex(branchKey)` | Year branch | `GuGuaIndex{GuchenIndex, GuasuIndex}` | | `GetJieshaAdjIndex(branchKey)` | Year branch | `int`, the palace index of Jiesha | | `GetDahaoIndex(branchKey)` | Year branch | `int`, the palace index of Dahao | | `GetNianjieIndex(branchKey)` | Year branch | `int`, the palace index of Nianjie | | `GetTianshiTianshangIndex(gender, branchKey, soulIndex, config)` | Gender, year branch, Soul palace index | `TianshiTianshangIndex{TianshangIndex, TianshiIndex}` | | `GetChangQuIndexByHeavenlyStem(stemKey)` | Heavenly stem | `ChangQuIndex{ChangIndex, QuIndex}` | **Example** ```go chart, _ := iztro.BySolar("2000-8-16", 2, iztro.GenderFemale, true, iztro.LanguageEnUS, nil) yearBranch := chart.RawDates.ChineseDate.YearlyKeys[1] hl, _ := iztro.GetHuoLingIndex(yearBranch, 2) gg, _ := iztro.GetGuGuaIndex(yearBranch) cq, _ := iztro.GetChangQuIndexByHeavenlyStem(iztro.StemJia) fmt.Println(hl, gg, cq) ``` **Output** ```text {2 10} {3 11} {3 7} ``` **Edge cases and pitfalls** `GetZuoYouIndex` takes the month after leap-month correction, i.e. `FixLunarMonthIndex(...) + 1` — not the raw lunar month. Passing the raw month on a leap-month chart lands in the wrong palace. The result of `GetTianshiTianshangIndex` follows `config.Algorithm`: the Zhongzhou school swaps Tianshang and Tianshi for yin men and yang women (where the birth-year branch polarity and the gender polarity differ), while the common school does not. Pass `nil` for `config` to take the defaults. `GetChangQuIndexByHeavenlyStem` places Wenchang and Wenqu from a heavenly stem and is used for the scope Wenchang and Wenqu of horoscope layers; the natal Wenchang and Wenqu go through `GetChangQuIndex` from the hour branch.