Struct arrow::datatypes::Schema[][src]

pub struct Schema { /* fields omitted */ }

Describes the meta-data of an ordered sequence of relative types.

Note that this information is only part of the meta-data and not part of the physical memory layout.

Implementations

impl Schema[src]

pub fn empty() -> Self[src]

Creates an empty Schema

pub fn new(fields: Vec<Field>) -> Self[src]

Creates a new Schema from a sequence of Field values.

Example

let field_a = Field::new("a", DataType::Int64, false);
let field_b = Field::new("b", DataType::Boolean, false);

let schema = Schema::new(vec![field_a, field_b]);

pub const fn new_with_metadata(
    fields: Vec<Field>,
    metadata: HashMap<String, String>
) -> Self
[src]

Creates a new Schema from a sequence of Field values and adds additional metadata in form of key value pairs.

Example

let field_a = Field::new("a", DataType::Int64, false);
let field_b = Field::new("b", DataType::Boolean, false);

let mut metadata: HashMap<String, String> = HashMap::new();
metadata.insert("row_count".to_string(), "100".to_string());

let schema = Schema::new_with_metadata(vec![field_a, field_b], metadata);

pub fn try_merge(schemas: impl IntoIterator<Item = Self>) -> Result<Self>[src]

Merge schema into self if it is compatible. Struct fields will be merged recursively.

Example:

use arrow::datatypes::*;

let merged = Schema::try_merge(vec![
    Schema::new(vec![
        Field::new("c1", DataType::Int64, false),
        Field::new("c2", DataType::Utf8, false),
    ]),
    Schema::new(vec![
        Field::new("c1", DataType::Int64, true),
        Field::new("c2", DataType::Utf8, false),
        Field::new("c3", DataType::Utf8, false),
    ]),
]).unwrap();

assert_eq!(
    merged,
    Schema::new(vec![
        Field::new("c1", DataType::Int64, true),
        Field::new("c2", DataType::Utf8, false),
        Field::new("c3", DataType::Utf8, false),
    ]),
);

pub const fn fields(&self) -> &Vec<Field>[src]

Returns an immutable reference of the vector of Field instances.

pub fn field(&self, i: usize) -> &Field[src]

Returns an immutable reference of a specific Field instance selected using an offset within the internal fields vector.

pub fn field_with_name(&self, name: &str) -> Result<&Field>[src]

Returns an immutable reference of a specific Field instance selected by name.

pub fn fields_with_dict_id(&self, dict_id: i64) -> Vec<&Field>[src]

Returns a vector of immutable references to all Field instances selected by the dictionary ID they use.

pub fn index_of(&self, name: &str) -> Result<usize>[src]

Find the index of the column with the given name.

pub const fn metadata(&self) -> &HashMap<String, String>[src]

Returns an immutable reference to the Map of custom metadata key-value pairs.

pub fn column_with_name(&self, name: &str) -> Option<(usize, &Field)>[src]

Look up a column by name and return a immutable reference to the column along with its index.

pub fn to_json(&self) -> Value[src]

Generate a JSON representation of the Schema.

pub fn from(json: &Value) -> Result<Self>[src]

Parse a Schema definition from a JSON representation.

pub fn contains(&self, other: &Schema) -> bool[src]

Check to see if self is a superset of other schema. Here are the comparision rules:

  • self and other should contain the same number of fields
  • for every field f in other, the field in self with corresponding index should be a superset of f.
  • self.metadata is a superset of other.metadata

In other words, any record conforms to other should also conform to self.

Trait Implementations

impl Clone for Schema[src]

impl Debug for Schema[src]

impl<'de> Deserialize<'de> for Schema[src]

impl Display for Schema[src]

impl Eq for Schema[src]

impl PartialEq<Schema> for Schema[src]

impl Serialize for Schema[src]

impl StructuralEq for Schema[src]

impl StructuralPartialEq for Schema[src]

Auto Trait Implementations

impl RefUnwindSafe for Schema

impl Send for Schema

impl Sync for Schema

impl Unpin for Schema

impl UnwindSafe for Schema

Blanket Implementations

impl<T> Any for T where
    T: 'static + ?Sized
[src]

impl<T> Borrow<T> for T where
    T: ?Sized
[src]

impl<T> BorrowMut<T> for T where
    T: ?Sized
[src]

impl<T> DeserializeOwned for T where
    T: for<'de> Deserialize<'de>, 
[src]

impl<Q, K> Equivalent<K> for Q where
    K: Borrow<Q> + ?Sized,
    Q: Eq + ?Sized
[src]

impl<T> From<T> for T[src]

impl<T, U> Into<U> for T where
    U: From<T>, 
[src]

impl<T> ToOwned for T where
    T: Clone
[src]

type Owned = T

The resulting type after obtaining ownership.

impl<T> ToString for T where
    T: Display + ?Sized
[src]

impl<T, U> TryFrom<U> for T where
    U: Into<T>, 
[src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, 
[src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

impl<V, T> VZip<V> for T where
    V: MultiLane<T>,