# Astrolabe object (/en/docs/rust/astrolabe) The fields of Astrolabe, its lookup methods, and the surrounded-palace predicates. `Astrolabe` is what charting produces and the entry point for every query. It holds all the data of the twelve palaces along with chart-level information such as the four pillars, the soul and body stars and the five elements class. ```rust let chart = by_solar("2000-8-16", 2, Gender::Female, true, Language::EnUS, Config::default())?; ``` The examples on this page all chart with `Language::EnUS`, so the display values in the output are iztro's en-US vocabulary — `emperor` for Ziwei, `soul` for the Soul palace, and so on. Charting in another language changes those strings only; the `*_key` fields and every predicate stay the same. ## Fields [#fields] | Field | Type | Description | | -------------- | -------- | ------------------------------------------------------------------------------------------------------------ | | `gender` | `Gender` | Gender | | `solar_date` | `String` | Solar date, as passed in | | `lunar_date` | `String` | The lunar date written in Chinese numerals, e.g. `二〇〇〇年七月十七` — "the 17th day of the 7th lunar month of 2000" | | `chinese_date` | `String` | Display string of the four pillars, e.g. `geng chen - jia shen - bing woo - geng yin` | | `time` | `String` | Hour name, e.g. `Tiger hour` | | `time_range` | `String` | The clock range of that hour, e.g. `03:00~05:00` | | `sign` | `String` | Zodiac sign, from the solar date | | `zodiac` | `String` | Chinese zodiac animal, from the year branch | Display fields follow `language`. For predicates use the key fields in the next group. | Field | Type | Description | | ------------------------------- | ------------------- | -------------------------------------------------------------------------------------------- | | `sign_key` | `String` | Zodiac sign key, `aries` … `pisces` | | `zodiac_key` | `String` | Zodiac animal key, `rat` … `pig` | | `earthly_branch_of_soul_palace` | `EarthlyBranch` | Branch of the Soul palace | | `earthly_branch_of_body_palace` | `EarthlyBranch` | Branch of the body palace | | `soul` | `StarKey` | Soul star | | `body` | `StarKey` | Body star | | `five_elements_class` | `FiveElementsClass` | Five elements class, which sets the starting age of the decadal scope and where Ziwei begins | These are strongly typed enums, independent of language, and can be compared directly. | Field | Type | Description | | ----------- | ------------------ | --------------------------------------------------------------------------------------- | | `palaces` | `[PalaceData; 12]` | The twelve palaces as a fixed-size array; index 0 is the Yin palace, 11 the Chou palace | | `raw_dates` | `RawDates` | The structured lunar birth date and the four pillars as enums | Indices into `palaces` are **palace indices**, not the palace-name order: `palaces[0]` is always the Yin palace, and the Soul palace can be in any of the cells. Fetch it with `chart.palace(Palace::Soul)`. `raw_dates` is the data form of the two display strings `lunar_date` and `chinese_date`. Use it for date arithmetic or stem-and-branch lookups instead of parsing the Chinese strings: ```rust pub struct RawDates { pub lunar_date: RawLunarDate, pub chinese_date: RawChineseDate, } pub struct RawLunarDate { pub lunar_year: i64, // lunar year pub lunar_month: u32, // lunar month 1–12; whether it is a leap month is in is_leap pub lunar_day: u32, // lunar day 1–30 pub is_leap: bool, // whether it is a leap month } pub struct RawChineseDate { pub yearly: (HeavenlyStem, EarthlyBranch), // year pillar pub monthly: (HeavenlyStem, EarthlyBranch), // month pillar pub daily: (HeavenlyStem, EarthlyBranch), // day pillar pub hourly: (HeavenlyStem, EarthlyBranch), // hour pillar } ``` All three types are re-exported at the crate root, so `use x_iztro::*;` is enough. | Field | Type | Description | | ------------ | ---------- | -------------------------------------------------------------------------------------------------------- | | `time_index` | `u8` | Birth hour index, kept as passed in even when `day_divide` reassigns the late Zi hour to the current day | | `fix_leap` | `bool` | Whether leap-month correction was applied when charting | | `language` | `Language` | Output language | | `config` | `Config` | Charting configuration | Horoscopes and prompts restart their computation from these four, so the charting parameters need not be supplied again. *** ## palace [#palace] **Purpose** Fetch a palace by index, by name, or as the body or original palace. **Zi Wei meaning** The twelve palaces are the skeleton of a chart. Once the Soul palace is fixed the other eleven follow counterclockwise in a fixed order. The "body palace" is whichever of the twelve also carries that flag, marking where acquired effort concentrates; the "original palace" is the one whose stem matches the birth-year stem, marking where matters originate. **Signature** ```rust pub fn palace(&self, target: impl Into) -> Option> ``` **Parameters** | Parameter | Type | Required | Default | Description | | --------- | ------------------------- | -------- | ------- | ----------------------------------- | | `target` | `impl Into` | Yes | — | Four spellings, see the table below | All four variants of `PalaceTarget` have `From` implementations, so you write the value directly: | Spelling | Example | Meaning | | --------------- | -------------------------------------- | ------------------------------------------------- | | Index | `chart.palace(0)` | Palace index 0–11, where 0 is the Yin palace | | Name | `chart.palace(Palace::Soul)` | One of the twelve palace names | | Body palace | `chart.palace(PalaceTarget::Body)` | Whichever palace carries the body-palace flag | | Original palace | `chart.palace(PalaceTarget::Original)` | The palace whose stem matches the birth-year stem | **Return value** `Option>`. An out-of-range index returns `None`; the name, body-palace and original-palace spellings resolve on any chart and are never `None`. **Example** ```rust let en = Language::EnUS; let soul = chart.palace(Palace::Soul).unwrap(); println!("{} {} {}", translate_palace(soul.name, en), translate_heavenly_stem(soul.heavenly_stem, en), translate_earthly_branch(soul.earthly_branch, en)); let body = chart.palace(PalaceTarget::Body).unwrap(); println!("body palace falls in {}", translate_palace(body.name, en)); let original = chart.palace(PalaceTarget::Original).unwrap(); println!("original palace is {}", translate_palace(original.name, en)); println!("the Yin palace is {}", translate_palace(chart.palace(0).unwrap().name, en)); ``` `PalaceData::name` has the type `Palace`, an enum rather than a string, so it cannot be printed with `{}` directly — the enum is a language-independent key, and display goes through `translate_palace` to get text in the current language. The same holds for `heavenly_stem`, `earthly_branch`, `five_elements_class` and the other enum fields. **Output** ```text soul ren woo body palace falls in career original palace is spouse the Yin palace is wealth ``` **Edge cases and pitfalls** The original palace requires the palace stem to equal the birth-year stem, and the palace not to be Zi or Chou. Palace stems run forward from the Yin palace under the Five Tigers rule, and the ten palaces from Yin to You walk the ten stems exactly once; Zi and Chou are the eleventh and twelfth cells and repeat the stems of Yin and Mao — and it is precisely that repetition that excludes them. So any birth-year stem hits exactly once between Yin and You: on every chart the original palace exists, and it is unique. Each of the twelve palace names appears exactly once on a chart, so a lookup by name is necessarily unique. The body palace is a **flag**, not a name — it is also one of the twelve palaces (the Career palace in the example above). The same goes for the original palace, which lands on the Spouse palace here. *** ## star [#star] **Purpose** Find a star by key and get a view that can trace back to its palace. **Signature** ```rust pub fn star(&self, key: StarKey) -> Option> ``` **Parameters** | Parameter | Type | Required | Default | Description | | --------- | --------- | -------- | ------- | ---------------------------------- | | `key` | `StarKey` | Yes | — | Star key, e.g. `StarKey::ZiweiMaj` | **Return value** `Option>`. `None` when the star is not on this chart. **Example** ```rust let en = Language::EnUS; let ziwei = chart.star(StarKey::ZiweiMaj).unwrap(); println!("{} sits in {}", ziwei.name, translate_palace(ziwei.palace().name, en)); println!("its opposite palace is {}", translate_palace(ziwei.opposite_palace().name, en)); println!("brightness {:?} mutagen {:?}", ziwei.brightness, ziwei.mutagen); ``` `Star::name` is a `String` (already translated into the charting language) and prints directly; `PalaceData::name` is an enum and goes through `translate_palace`. **Output** ```text emperor sits in soul its opposite palace is surface brightness Some(Miao) mutagen None ``` **Edge cases and pitfalls** The search covers only the three groups of major, minor and adjective stars. The Changsheng, Boshi, Sui-qian and Jiang-qian gods are one-per-palace marks rather than star lists — read them from fields like `palace.changsheng12`. *** ## surrounded\_palaces [#surrounded_palaces] **Purpose** Fetch the surrounded palaces of a target palace. **Zi Wei meaning** The surrounded set is the most commonly used reading scope in Zi Wei Dou Shu: the palace itself, its opposite (index +6), the career position (+4) and the wealth position (+8). The four are read together rather than the palace alone, because the stars of the opposite and trine palaces bear on the palace's affairs just as much. **Signature** ```rust pub fn surrounded_palaces(&self, target: impl Into) -> Option> ``` **Parameters** Same as `palace`; all four spellings are supported. **Return value** `Option>`, holding the four `&PalaceData` values `target` / `opposite` / `wealth` / `career` (not `PalaceRef`s: their fields read directly, but they carry none of the methods that need the astrolabe for context, such as the opposite palace or flying stars). Its predicates are on [Surrounded palaces](/en/docs/rust/surpalaces). **Example** ```rust let en = Language::EnUS; let sp = chart.surrounded_palaces(Palace::Soul).unwrap(); println!("{} / {} / {} / {}", translate_palace(sp.target.name, en), translate_palace(sp.opposite.name, en), translate_palace(sp.wealth.name, en), translate_palace(sp.career.name, en)); println!("Ziwei in the surrounded set: {}", sp.have(&[StarKey::ZiweiMaj])); ``` **Output** ```text soul / surface / wealth / career Ziwei in the surrounded set: true ``` *** ## is\_surrounded / is\_surrounded\_one\_of / not\_surrounded [#is_surrounded--is_surrounded_one_of--not_surrounded] **Purpose** Test the surrounded palaces of a palace straight from the astrolabe, skipping the step of fetching the set first. **Signature** ```rust pub fn is_surrounded(&self, target: impl Into, stars: &[StarKey]) -> bool pub fn is_surrounded_one_of(&self, target: impl Into, stars: &[StarKey]) -> bool pub fn not_surrounded(&self, target: impl Into, stars: &[StarKey]) -> bool ``` **Parameters** | Parameter | Type | Required | Default | Description | | --------- | ------------------------- | -------- | ------- | ----------------------------------- | | `target` | `impl Into` | Yes | — | Located the same way as in `palace` | | `stars` | `&[StarKey]` | Yes | — | A list of star keys | **Return value** | Method | Meaning | | ---------------------- | ---------------------------------------------------------- | | `is_surrounded` | **Every** star in the list is in the surrounded set | | `is_surrounded_one_of` | **At least one** star in the list is in the surrounded set | | `not_surrounded` | **None** of the stars in the list is in the surrounded set | **Example** ```rust use x_iztro::StarKey::*; println!("{}", chart.is_surrounded(Palace::Soul, &[ZiweiMaj, TianxiangMaj])); println!("{}", chart.is_surrounded_one_of(Palace::Soul, &[QishaMaj, PojunMaj])); println!("{}", chart.not_surrounded(Palace::Soul, &[HuoxingMin])); ``` **Output** ```text true false true ``` The Soul palace holds only Ziwei, while Tianxiang sits in the Wealth palace, one of the trine — hence `true` on the first line. Neither Qisha nor Pojun is in any of the four, hence `false` on the second. **Edge cases and pitfalls** With an empty `stars` slice, `is_surrounded` and `not_surrounded` return `true` ("all elements satisfy" and "no element fails" both hold vacuously) while `is_surrounded_one_of` returns `false`. Make sure the list is non-empty before calling. *** ## horoscope / horoscope\_now [#horoscope--horoscope_now] **Purpose** Compute the horoscope for a target date, starting from this chart. **Signature** ```rust pub fn horoscope(&self, target_date: &str, target_time_index: u8) -> Result, IztroError> pub fn horoscope_now(&self) -> Result, IztroError> ``` **Parameters** | Parameter | Type | Required | Default | Description | | ------------------- | ------ | -------- | ------- | ---------------------------------------------------- | | `target_date` | `&str` | Yes | — | Target solar date in `YYYY-M-D` | | `target_time_index` | `u8` | Yes | — | Target hour index 0–12, which fixes the hourly scope | `horoscope_now` takes the current date and hour from the local clock and has no parameters. **Return value** `HoroscopeRef<'_>` — a horoscope view holding this chart, so palace lookups across the six scopes need not be passed the astrolabe again. Details on [the horoscope object](/en/docs/rust/horoscope). **Example** ```rust let en = Language::EnUS; let h = chart.horoscope("2025-6-1", 0)?; println!("decadal {} {}", translate_heavenly_stem(h.decadal.heavenly_stem, en), translate_earthly_branch(h.decadal.earthly_branch, en)); println!("yearly {} {}", translate_heavenly_stem(h.yearly.heavenly_stem, en), translate_earthly_branch(h.yearly.earthly_branch, en)); ``` `decadal` / `monthly` / `daily` / `hourly` are `HoroscopeItem`s whose pillars read directly, while `yearly` and `age` each carry one extra datum of their own (the shared fields sit under `base`), but both implement `Deref`, so `h.yearly.heavenly_stem` reads directly as well. **Output** ```text decadal geng chen yearly yi si ``` *** ## to\_text [#to_text] **Purpose** The chart's semantic text: a complete description for language models and people. **Signature** ```rust pub fn to_text(&self) -> String ``` Emits in the charting language; for an explicit language use the free function `text::astrolabe_to_text(astrolabe, lang)` — `lang` may differ from the charting language, with every field re-translated by key into the target language. For single palaces and surrounded palaces see `PalaceRef::to_text()` / `SurroundedPalaces::to_text(lang)`. The full format is on [Semantic text](/en/docs/guide/guides/to-text). **Example** ```rust println!("{}", chart.to_text().chars().take(77).collect::()); ``` **Output** ```text === Basic Info === Gender: female Solar Date: 2000-8-16 Lunar Date: 二〇〇〇年七月十七 ``` *** ## to\_dto [#to_dto] **Purpose** Convert the chart into the serialization structure that matches the JS iztro field contract. **Signature** ```rust pub fn to_dto(&self) -> AstrolabeDto ``` **Return value** `x_iztro::dto::AstrolabeDto` — camelCase keys with values translated into the **charting language**, plus the language-independent `*Key` fields and the charting context (`genderKey` / `timeIndex` / `fixLeap` / `language` / `config`). The field list is on [the data model](/en/docs/guide/data-model). **Example** ```rust let dto = chart.to_dto(); let json = serde_json::to_string(&dto)?; let v: serde_json::Value = serde_json::from_str(&json)?; println!("{} {}", v["solarDate"], v["palaces"][4]["nameKey"]); println!("{}", v["config"]["yearDivide"]); ``` **Output** ```text "2000-8-16" "soulPalace" "normal" ``` **Edge cases and pitfalls** The DTO is for the language bindings and for frontends. For analysis on the Rust side use `Astrolabe` itself — it has every query method, while the DTO is only data. To get a JSON string in one step, use [`by_solar_json`](/en/docs/rust/astro#by_solar_json--by_lunar_json). The `overrides` of `Config` (the custom mutagen and brightness tables) do not go into the DTO: they are charting input rather than result, and echoing them back would break the field contract with JS iztro.