# Horoscope object (/en/docs/rust/horoscope)
The data structures of the six scopes, plus palace lookups that need not be handed the astrolabe again.
A horoscope projects the natal chart onto a point in time. The same chart shows a different palace
layout in different years — which is exactly what "the decadal scope has moved to that palace" means.
```rust
let h = chart.horoscope("2025-6-1", 0)?;
```
`HoroscopeRef` holds the natal chart that produced it, so none of the query methods need the
astrolabe passed in again.
The examples on this page all start from a `Language::EnUS` natal chart, so the display values in the
output are iztro's en-US vocabulary.
## HoroscopeData [#horoscopedata]
`HoroscopeRef` derefs to `HoroscopeData`, which has eight fields: two date strings and the six scopes.
| Field | Type | Description |
| ------------ | --------------- | --------------------------------------------------------- |
| `solar_date` | `String` | Target solar date, as passed in |
| `lunar_date` | `String` | The target date's lunar form, written in Chinese numerals |
| `decadal` | `HoroscopeItem` | The decadal scope |
| `age` | `AgeItem` | The age scope |
| `yearly` | `YearlyItem` | The yearly scope |
| `monthly` | `HoroscopeItem` | The monthly scope |
| `daily` | `HoroscopeItem` | The daily scope |
| `hourly` | `HoroscopeItem` | The hourly scope |
`solar_date` is the **target** date, not the birth date; the birth date lives on the natal chart, as
`h.astrolabe().solar_date`.
## The six scopes [#the-six-scopes]
| Field | Type | Span | Description |
| --------- | --------------- | --------------- | --------------------------------------------------------------------- |
| `decadal` | `HoroscopeItem` | Ten years | The decadal scope; the childhood scope for the years before it begins |
| `age` | `AgeItem` | One year | The age scope, moving one palace per nominal year |
| `yearly` | `YearlyItem` | One year | The yearly scope, its palace fixed by the year's pillar |
| `monthly` | `HoroscopeItem` | One month | The monthly scope |
| `daily` | `HoroscopeItem` | One day | The daily scope |
| `hourly` | `HoroscopeItem` | One double-hour | The hourly scope |
Both advance once per year, but they start differently: the age scope starts from the birth-year
branch and steps forward with the nominal age, while the yearly scope simply asks which palace that
year's pillar falls in. The two lines are independent, and Zi Wei practice usually reads them
together.
### HoroscopeItem [#horoscopeitem]
| Field | Type | Description |
| ---------------- | ------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `index` | `usize` | Which palace this scope lands on (a palace index) |
| `name` | `String` | Display name of the scope, translated into the output language |
| `name_key` | `HoroscopeName` | The scope's language-independent key; before the decadals begin the decadal scope carries `Childhood`, a different reading semantics from `Decadal` — predicate on this, never on the translation |
| `heavenly_stem` | `HeavenlyStem` | Stem of the scope, which determines the mutagens it flies |
| `earthly_branch` | `EarthlyBranch` | Branch of the scope |
| `palace_names` | `Vec` | The twelve palace names re-derived with this scope's palace as the Soul palace, indexed by palace index |
| `mutagen` | `Vec` | The stars this scope's stem transforms, in the order lu, quan, ke, ji |
| `stars` | `Option>>` | The scope stars of this layer; `None` for layers that have none |
`age` and `yearly` are not `HoroscopeItem`s themselves but wrappers carrying one extra datum each:
```rust
pub struct AgeItem {
pub base: HoroscopeItem,
pub nominal_age: u32, // the nominal age for that date
}
pub struct YearlyItem {
pub base: HoroscopeItem,
pub yearly_dec_star: YearlyDecStar,
}
pub struct YearlyDecStar {
pub jiangqian12: Vec, // the yearly Jiang-qian gods, indexed by palace index
pub suiqian12: Vec, // the yearly Sui-qian gods, indexed by palace index
}
```
`AgeItem` and `YearlyItem` both implement `Deref`, so the shared fields
read directly: `h.yearly.heavenly_stem`, `h.age.index`; take `.base` when you need the whole
`HoroscopeItem`. All four types are re-exported at the crate root.
**Example**
```rust
let h = chart.horoscope("2025-6-1", 0)?;
for item in [&h.decadal, &h.monthly, &h.daily, &h.hourly] {
println!("{} lands on palace {} with pillar {} {}", item.name, item.index,
translate_heavenly_stem(item.heavenly_stem, Language::EnUS),
translate_earthly_branch(item.earthly_branch, Language::EnUS));
}
println!("age scope nominal age {}", h.age.nominal_age);
```
**Output**
```text
decadal lands on palace 2 with pillar geng chen
monthly lands on palace 3 with pillar ren woo
daily lands on palace 8 with pillar xin chou
hourly lands on palace 8 with pillar wu zi
age scope nominal age 26
```
***
## age\_palace [#age_palace]
**Purpose** Get the palace the age scope occupies this year.
**Zi Wei meaning** The age scope is a line advancing year by year; whichever palace it lands on
becomes the focus for that year.
**Signature**
```rust
pub fn age_palace(&self) -> PalaceRef<'a>
```
**Return value** `PalaceRef` — a palace on the natal chart, always present.
**Example**
```rust
let h = chart.horoscope("2025-6-1", 0)?;
println!("{}", translate_palace(h.age_palace().name, Language::EnUS));
```
**Output**
```text
property
```
***
## palace [#palace]
**Purpose** Get one of the twelve palaces as re-derived under a given horoscope scope.
**Zi Wei meaning** Once the decadal scope reaches a palace, the twelve palaces are re-anchored with
that palace as the "decadal Soul palace". "The decadal Spouse palace" refers to that re-anchored
naming, and it is usually not the same palace as the natal Spouse palace.
**Signature**
```rust
pub fn palace(&self, name: Palace, scope: Scope) -> Option>
```
**Parameters**
| Parameter | Type | Required | Default | Description |
| --------- | -------- | -------- | ------- | -------------------------------------- |
| `name` | `Palace` | Yes | — | The palace name to fetch |
| `scope` | `Scope` | Yes | — | Which scope's twelve palaces to search |
**Return value** `Option>` — a palace on the natal chart (the same cell carries
different names under different scopes). With `Origin` as the scope, these are the natal twelve
palaces.
**Example**
```rust
let en = Language::EnUS;
let h = chart.horoscope("2025-6-1", 0)?;
println!("the decadal Soul palace is the natal {}",
translate_palace(h.palace(Palace::Soul, Scope::Decadal).unwrap().name, en));
println!("the natal Soul palace is {}",
translate_palace(h.palace(Palace::Soul, Scope::Origin).unwrap().name, en));
```
**Output**
```text
the decadal Soul palace is the natal spouse
the natal Soul palace is soul
```
**Edge cases and pitfalls**
On the palace object returned by `palace(Soul, Decadal)`, `name` is still the **natal palace name**
(Spouse in the example), because it is that cell on the natal chart. To see what the cell is called at
the decadal layer, read `h.decadal.palace_names[index]`.
***
## surround\_palaces [#surround_palaces]
**Purpose** Get the surrounded palaces of a palace under a given horoscope scope.
**Signature**
```rust
pub fn surround_palaces(&self, name: Palace, scope: Scope) -> Option>
```
**Parameters** Same as `palace`.
**Return value** `Option>`; its predicates are on
[Surrounded palaces](/en/docs/rust/surpalaces).
**Example**
```rust
let h = chart.horoscope("2025-6-1", 0)?;
let sp = h.surround_palaces(Palace::Wealth, Scope::Yearly).unwrap();
println!("the surrounded set of the yearly Wealth palace is anchored on the natal {}",
translate_palace(sp.target.name, Language::EnUS));
```
**Output**
```text
the surrounded set of the yearly Wealth palace is anchored on the natal health
```
***
## has\_horoscope\_stars / has\_one\_of\_horoscope\_stars / not\_have\_horoscope\_stars [#has_horoscope_stars--has_one_of_horoscope_stars--not_have_horoscope_stars]
**Purpose** Test whether a palace under a given scope holds the given scope stars.
**Zi Wei meaning** Scope stars are a group produced by each horoscope layer: Tiankui, Tianyue,
Wenchang, Wenqu, Lucun, Qingyang, Tuoluo, Tianma, Hongluan and Tianxi.
They carry different names in different layers — Yunkui and Yunyue at the decadal layer, Liukui and
Liuyue at the yearly layer — with the same meaning applied to their own time span.
**Signature**
```rust
pub fn has_horoscope_stars(&self, name: Palace, scope: Scope, stars: &[StarKey]) -> bool
pub fn has_one_of_horoscope_stars(&self, name: Palace, scope: Scope, stars: &[StarKey]) -> bool
pub fn not_have_horoscope_stars(&self, name: Palace, scope: Scope, stars: &[StarKey]) -> bool
```
**Parameters**
| Parameter | Type | Required | Default | Description |
| --------- | ------------ | -------- | ------- | -------------------------------------------------- |
| `name` | `Palace` | Yes | — | The palace name under that scope |
| `scope` | `Scope` | Yes | — | The horoscope scope |
| `stars` | `&[StarKey]` | Yes | — | Scope star keys, which must use that layer's names |
**Return value**
| Method | Meaning |
| ---------------------------- | ----------------------- |
| `has_horoscope_stars` | All of them are present |
| `has_one_of_horoscope_stars` | At least one is present |
| `not_have_horoscope_stars` | None is present |
**Example**
```rust
use x_iztro::StarKey::*;
let h = chart.horoscope("2025-6-1", 0)?;
println!("{}", h.has_horoscope_stars(Palace::Soul, Scope::Decadal, &[Yunlu]));
println!("{}", h.has_one_of_horoscope_stars(Palace::Soul, Scope::Decadal, &[Yunlu, Yunyang]));
println!("{}", h.not_have_horoscope_stars(Palace::Soul, Scope::Decadal, &[Yuntuo]));
```
**Output**
```text
false
false
true
```
**Edge cases and pitfalls**
The three methods use `scope` + `name` to locate one cell on the natal chart, but the set of stars
compared against is always the **union of the decadal and yearly scope stars**, regardless of `scope`.
So with `scope` set to `Monthly` the question is "does this cell, named as a monthly palace, hold any
decadal or yearly scope star?" — not the monthly scope's own stars. The scope stars of the monthly,
daily and hourly layers take no part in the comparison here.
For a layer's scope-star distribution, use a field like `h.monthly.stars`, or
[`get_horoscope_stars`](/en/docs/rust/star#get_horoscope_stars).
The decadal scope stars are `Yunlu`, `Yunyang` and so on, the yearly ones `Liulu`, `Liuyang` and so
on; the two groups have different key names. Since the compared set is always the union of those two
groups, both `Yunlu` and `Liulu` can be found under any `scope` — only their palaces differ.
The per-layer key table is on [Star placement](/en/docs/rust/star#get_horoscope_stars).
`Origin` walks the natal twelve palaces, so a palace is still located; there simply are no scope stars
on the natal chart, and what is compared remains whichever decadal and yearly scope stars fall on that
cell.
***
## has\_horoscope\_mutagen [#has_horoscope_mutagen]
**Purpose** Test whether a palace under a given scope carries a mutagen flown by that scope's stem.
**Zi Wei meaning** Every horoscope layer has a stem of its own, and it transforms four stars just as
the birth-year stem does. A question like "does the decadal lu land in the decadal Wealth palace?" is
asking about this.
**Signature**
```rust
pub fn has_horoscope_mutagen(&self, name: Palace, scope: Scope, mutagen: Mutagen) -> bool
```
**Parameters**
| Parameter | Type | Required | Default | Description |
| --------- | --------- | -------- | ------- | -------------------------------- |
| `name` | `Palace` | Yes | — | The palace name under that scope |
| `scope` | `Scope` | Yes | — | The horoscope scope |
| `mutagen` | `Mutagen` | Yes | — | One of the four mutagens |
**Return value** `bool`. It checks whether the star transformed by that layer's stem sits among the
target palace's major or minor stars (adjective stars are not considered).
**Example**
```rust
let h = chart.horoscope("2025-6-1", 0)?;
println!("{}", h.has_horoscope_mutagen(Palace::Soul, Scope::Decadal, Mutagen::Lu));
// the four stars this layer transforms can be read directly
println!("{:?}", h.decadal.mutagen.iter()
.map(|s| translate_star(*s, Language::EnUS)).collect::>());
```
**Output**
```text
false
["sun", "general", "moon", "fortunate"]
```
The decadal stem is geng, and geng sends lu to Taiyang (`sun`), quan to Wuqu (`general`), ke to Taiyin
(`moon`) and ji to Tiantong (`fortunate`).
**Edge cases and pitfalls**
There is no such thing as a "layer stem" at the natal layer — the natal mutagens are already marked on
the stars' own `mutagen` fields.
`has_horoscope_mutagen(name, Scope::Origin, m)` therefore returns `false` outright, which does not
mean the natal chart lacks that mutagen. For natal mutagens use the palace's
[`has_mutagen`](/en/docs/rust/palace#has_mutagen--not_have_mutagen).
***
## astrolabe / data / into\_data [#astrolabe--data--into_data]
**Purpose** Get back to the natal chart, or take out the horoscope's plain data.
**Signature**
```rust
pub fn astrolabe(&self) -> &'a Astrolabe
pub fn data(&self) -> &HoroscopeData
pub fn into_data(self) -> HoroscopeData
```
**Return value**
| Method | Use |
| ----------- | ------------------------------------------------------------------------------------------ |
| `astrolabe` | Back to the natal chart that produced this horoscope |
| `data` | Borrow the underlying data; the view implements `Deref`, so `h.decadal` usually suffices |
| `into_data` | Take the data and drop the borrow of the astrolabe, for cases needing a `'static` lifetime |
**Example**
```rust
let h = chart.horoscope("2025-6-1", 0)?;
println!("{}", h.astrolabe().solar_date);
let data: HoroscopeData = h.into_data(); // no longer borrows chart
println!("{}", data.solar_date);
```
**Output**
```text
2000-8-16
2025-6-1
```
***
## to\_text [#to_text]
**Purpose** The horoscope's semantic text: a complete description for language models and people.
**Signature**
```rust
pub fn to_text(&self) -> String
```
Defined on `HoroscopeRef` and emitting in the chart's charting language; for an explicit language use
the free function `text::horoscope_to_text(astrolabe, horoscope, lang)`.
**Return value** `String` — sectioned plain text; each scope carries a patterns line and
flowing-star lines from its own perspective. The full format is on
[Semantic text](/en/docs/guide/guides/to-text).
**Example**
```rust
let h = chart.horoscope("2025-1-1", 0)?;
println!("{}", h.to_text().chars().take(39).collect::());
```
**Output**
```text
=== Horoscope ===
Target Date: 2025-1-1
```
***
## to\_dto [#to_dto]
**Purpose** Convert the horoscope data into the serialization structure that matches the JS iztro
field contract.
**Signature**
```rust
pub fn to_dto(&self, lang: Language) -> HoroscopeDto
```
**Parameters**
| Parameter | Type | Required | Default | Description |
| --------- | ---------- | -------- | ------- | ---------------------------------------- |
| `lang` | `Language` | Yes | — | Which language the translated fields use |
It is defined on `HoroscopeData` (not on `HoroscopeRef`). The horoscope data does not itself record a
language, so it has to be given explicitly here — usually `chart.language`, to stay consistent with
the natal chart.
**Return value** `x_iztro::dto::HoroscopeDto`, camelCase keys plus the `*Key` identifiers.
**Example**
```rust
let h = chart.horoscope("2025-6-1", 0)?;
let json = serde_json::to_string(&h.to_dto(chart.language))?;
let v: serde_json::Value = serde_json::from_str(&json)?;
println!("{} {}", v["solarDate"], v["decadal"]["heavenlyStem"]);
println!("{}", v["age"]["nominalAge"]);
```
**Output**
```text
"2025-6-1" "geng"
26
```