# Data tables (/en/docs/go/data)

Star information, stem and branch information, ordering constants and all the key constants.



The input tables of the charting algorithm, plus the language-independent key constants.

***

## StarsInfo [#starsinfo]

**Purpose** Get the star information table.

**Signature**

```go
func StarsInfo() (map[string]StarInfo, error)
```

**Return value** Star key → `StarInfo`. Only twenty stars have an entry: the **fourteen major stars**
plus Wenchang, Wenqu, Huoxing, Lingxing, Qingyang and Tuoluo.

| Field          | Type       | Description                                                                                                                 |
| -------------- | ---------- | --------------------------------------------------------------------------------------------------------------------------- |
| `Brightness`   | `[]string` | Brightness keys across the twelve palaces, index 0 being the Yin palace; an empty string where the palace has no brightness |
| `FiveElements` | `string`   | Five element; an empty string when the table leaves it blank                                                                |
| `YinYang`      | `string`   | Polarity; an empty string when the table leaves it blank                                                                    |

**Example**

```go
info, _ := iztro.StarsInfo()

fmt.Println(len(info))
fmt.Printf("%+v\n", info[iztro.StarZiweiMaj])
fmt.Printf("%q\n", info[iztro.StarTaiyangMaj].FiveElements)
```

**Output**

```text
20
{Brightness:[wang wang de wang miao miao wang wang de wang ping miao] FiveElements:土 YinYang:阴}
""
```

**Edge cases and pitfalls**

<Callout type="warn" title="Five elements and polarity have gaps">
  Some stars have no five element or polarity in the table: both are empty for Taiyang and Qisha,
  polarity is empty for Tanlang, Tianxiang, Tianliang and Pojun, and both are empty for the six minor
  stars.

  Note also that `FiveElements` and `YinYang` are never internationalized — they are always the Chinese
  characters (`土`, `阴` and so on) in every output language.
</Callout>

***

## FlowStarCounterparts [#flowstarcounterparts]

**Purpose** The full table mapping flowing stars to their natal minor-star counterparts (50
entries).

**Signature**

```go
func FlowStarCounterparts() (map[string]string, error)
```

**Return value** Keys are flowing-star key constant values (`StarLiuchang` and friends), values
natal minor-star keys (`StarWenchangMin` and friends). Flowing stars have no knowledge-pack entries
of their own — their readings are looked up via the natal counterpart, and this table is the
official mapping.

**Example**

```go
m, _ := iztro.FlowStarCounterparts()

fmt.Println(m["liuchang"])
```

**Output**

```text
wenchangMin
```

***

## HeavenlyStems [#heavenlystems]

**Purpose** Get the heavenly stem information table.

**Zi Wei meaning** The mutagen table of the stems is the root of the whole mutagen system: the
birth-year stem determines the natal mutagens, a palace stem determines what that palace flies, and a
scope stem determines that layer's mutagens.

**Signature**

```go
func HeavenlyStems() (map[string]HeavenlyStemInfo, error)
```

**Return value** Stem key → `HeavenlyStemInfo`:

| Field          | Type       | Description                                                                |
| -------------- | ---------- | -------------------------------------------------------------------------- |
| `YinYang`      | `string`   | Polarity                                                                   |
| `FiveElements` | `string`   | Five element                                                               |
| `Crash`        | `string`   | Clashing stem key; an empty string for wu and ji, which clash with nothing |
| `Mutagen`      | `[]string` | The four mutagen star keys, in the order lu, quan, ke, ji                  |

**Example**

```go
stems, _ := iztro.HeavenlyStems()

fmt.Printf("%+v\n", stems[iztro.StemJia])
fmt.Printf("wu clashes with: %q\n", stems[iztro.StemWu].Crash)
```

**Output**

```text
{YinYang:阳 FiveElements:木 Crash:gengHeavenly Mutagen:[lianzhenMaj pojunMaj wuquMaj taiyangMaj]}
wu clashes with: ""
```

***

## EarthlyBranches [#earthlybranches]

**Purpose** Get the earthly branch information table.

**Signature**

```go
func EarthlyBranches() (map[string]EarthlyBranchInfo, error)
```

**Return value** Branch key → `EarthlyBranchInfo`:

| Field          | Type     | Description                                                                     |
| -------------- | -------- | ------------------------------------------------------------------------------- |
| `YinYang`      | `string` | Polarity, which sets the direction of the decadal scope and the Changsheng gods |
| `FiveElements` | `string` | Five element                                                                    |
| `Crash`        | `string` | Clashing branch key                                                             |
| `Soul`         | `string` | Soul star key (looked up by the Soul palace branch)                             |
| `Body`         | `string` | Body star key (looked up by the birth-year branch)                              |
| `Inside`       | `string` | Corresponding internal organ                                                    |
| `Outside`      | `string` | Corresponding body part                                                         |
| `HealthTip`    | `string` | Health note                                                                     |

<Callout type="info">
  `Inside`, `Outside` and `HealthTip` exist only in Chinese and take no part in internationalization.
</Callout>

**Example**

```go
branches, _ := iztro.EarthlyBranches()
fmt.Printf("%+v\n", branches[iztro.BranchZi])
```

**Output**

```text
{YinYang:阳 FiveElements:水 Crash:wuEarthly Soul:tanlangMaj Body:huoxingMin Inside:胆 Outside:下体 HealthTip:生殖系统、膀胱、尿道之疾病，听觉障碍}
```

***

## GetConstants [#getconstants]

**Purpose** Get the ordering constants and derivation rule tables.

**Signature**

```go
func GetConstants() (Constants, error)
```

**Return value** `Constants`:

| Field               | Type                | Description                                                                                                                                                                      |
| ------------------- | ------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `Languages`         | `[]string`          | Supported language codes                                                                                                                                                         |
| `HeavenlyStems`     | `[]string`          | Stem order                                                                                                                                                                       |
| `EarthlyBranches`   | `[]string`          | Branch order                                                                                                                                                                     |
| `Zodiac`            | `[]string`          | Chinese zodiac keys, in branch order                                                                                                                                             |
| `Signs`             | `[]string`          | Zodiac sign keys, in ecliptic order                                                                                                                                              |
| `Palaces`           | `[]string`          | The twelve palace names running **counterclockwise** from the Soul palace: Soul, Parents, Spirit, Property, Career, Friends, Surface, Health, Wealth, Children, Spouse, Siblings |
| `Gender`            | `map[string]string` | The polarity of each gender                                                                                                                                                      |
| `ChineseTime`       | `[]string`          | Hour keys, from the early Zi hour to the late Zi hour                                                                                                                            |
| `TimeRange`         | `[]string`          | The clock range of each hour                                                                                                                                                     |
| `TigerRule`         | `map[string]string` | Five Tigers rule: year stem to first-month stem                                                                                                                                  |
| `RatRule`           | `map[string]string` | Five Rats rule: day stem to Zi-hour stem                                                                                                                                         |
| `Mutagen`           | `[]string`          | Mutagen order                                                                                                                                                                    |
| `FiveElementsClass` | `map[string]int`    | Five elements class key → its number (water 2nd is 2 … fire 6th is 6)                                                                                                            |

**Example**

```go
c, _ := iztro.GetConstants()

fmt.Println(c.Languages)
fmt.Println(c.Zodiac[:3], c.ChineseTime[12], c.TimeRange[2])
fmt.Println(c.Gender)
fmt.Println("first-month stem of a jia year:", c.TigerRule[iztro.StemJia])
fmt.Println(c.Palaces)
fmt.Println(c.FiveElementsClass[iztro.ClassWood3rd], iztro.FiveElementsClassNumber(iztro.ClassFire6th))
```

**Output**

```text
[en-US ja-JP ko-KR zh-CN zh-TW vi-VN]
[rat ox tiger] lateRatHour 03:00~05:00
map[female:阴 male:阳]
first-month stem of a jia year: bingHeavenly
[soulPalace parentsPalace spiritPalace propertyPalace careerPalace friendsPalace surfacePalace healthPalace wealthPalace childrenPalace spousePalace siblingsPalace]
3 6
```

**Edge cases and pitfalls**

<Callout type="info" title="Palaces is a counterclockwise ordering, not a position on a chart">
  `Palaces` gives the **ordering** of the palace names, not what cell `i` is called on a particular
  chart. For that use [`GetPalaceNames(soulIndex)`](/en/docs/go/util#getpalacenames).
</Callout>

<Callout type="info" title="The class number can be looked up directly">
  `FiveElementsClassNumber(key)` does not need `Constants` first; an unknown key gives 0.
</Callout>

<Callout type="info">
  The order of `Languages` is the merge order of iztro's vocabularies (starting from en-US), not the
  declaration order of the constants. [`KeyOf`](/en/docs/go/i18n#keyof) scans the languages in that same
  order.
</Callout>

***

## Key constants [#key-constants]

The key constants in the package have the language-independent keys as their values and compare
directly against the `*Key` fields on the data objects.

| Prefix        | Count  | Examples                                                                                                         |
| ------------- | ------ | ---------------------------------------------------------------------------------------------------------------- |
| `Palace*`     | 12 + 2 | `PalaceSoul`, `PalaceWealth`, `PalaceBody`, `PalaceOriginal`                                                     |
| `Star*`       | 162    | `StarZiweiMaj`, `StarLucunMin`, `StarYunlu`                                                                      |
| `Stem*`       | 10     | `StemJia`, `StemGeng`                                                                                            |
| `Branch*`     | 12     | `BranchZi`, `BranchWu`                                                                                           |
| `Mutagen*`    | 4      | `MutagenLu`, `MutagenJi`                                                                                         |
| `Brightness*` | 7      | `BrightnessMiao`, `BrightnessWang`                                                                               |
| `Class*`      | 5      | `ClassWater2nd`, `ClassWood3rd`, `ClassMetal4th`, `ClassEarth5th`, `ClassFire6th`                                |
| `Scope*`      | 6      | `ScopeOrigin`, `ScopeDecadal`                                                                                    |
| `StarType*`   | 8      | `StarTypeMajor`, `StarTypeTough`                                                                                 |
| `Gender*`     | 2      | `GenderMale`, `GenderFemale` (type `Gender`)                                                                     |
| `Language*`   | 6      | `LanguageZhCN`, `LanguageZhTW`, `LanguageEnUS`, `LanguageJaJP`, `LanguageKoKR`, `LanguageViVN` (type `Language`) |
| `*LeapMonth*` | 3      | `NotLeapMonth`, `LeapMonthKeep`, `LeapMonthFixed` (type `LeapMonth`, how `ByLunar` treats the leap month)        |

`Gender`, `Language` and `LeapMonth` are named string types: as entry-point parameters the compiler
rejects any other string passed by mistake, while literals (`"male"`, `"zh-CN"`) still work;
`Astrolabe.GenderKey` and `Astrolabe.Language` are of these types too. The remaining constants are
untyped string constants that compare directly with the `*Key` fields.

The configuration values add six more groups:

| Prefix             | Values                                           |
| ------------------ | ------------------------------------------------ |
| `YearDivide*`      | `YearDivideNormal` / `YearDivideExact`           |
| `HoroscopeDivide*` | `HoroscopeDivideNormal` / `HoroscopeDivideExact` |
| `AgeDivide*`       | `AgeDivideNormal` / `AgeDivideBirthday`          |
| `DayDivide*`       | `DayDivideForward` / `DayDivideCurrent`          |
| `Algorithm*`       | `AlgorithmDefault` / `AlgorithmZhongzhou`        |
| `Astro*`           | `AstroHeaven` / `AstroEarth` / `AstroHuman`      |

<Callout type="warn" title="The five elements class constants are prefixed Class, not FiveElements">
  Write `iztro.ClassWood3rd`, not `iztro.FiveElementsWood3rd` — the latter does not exist and will not
  compile. For the class number use `iztro.FiveElementsClassNumber(key)`.
</Callout>

**Example**

```go
soul := chart.Palace(iztro.PalaceSoul)

fmt.Println(soul.MajorStars[0].Key == iztro.StarZiweiMaj)
fmt.Println(iztro.StarZiweiMaj, iztro.MutagenLu, iztro.PalaceWealth)
fmt.Println(iztro.ClassWood3rd, iztro.GenderFemale, iztro.LanguageEnUS)

// the gender and language parameters of the charting entries take these two groups too
en, err := iztro.BySolar("2000-8-16", 2, iztro.GenderFemale, true, iztro.LanguageEnUS, nil)
if err != nil {
    log.Fatal(err)
}
fmt.Println(en.Palace(iztro.PalaceSoul).MajorStars[0].Name)
```

**Output**

```text
true
ziweiMaj sihuaLu wealthPalace
wood3rd female en-US
emperor
```

<Callout type="info" title="Constants are equivalent to strings">
  They are all untyped string constants, so `chart.Palace("soulPalace")` and
  `chart.Palace(iztro.PalaceSoul)` are exactly equivalent.
  The constants earn their keep through IDE completion and spell checking, not through type enforcement.
</Callout>