Module polars::prelude [−][src]
Modules
Structs
A thread-safe reference-counting pointer. ‘Arc’ stands for ‘Atomically Reference Counted’.
A logical DataType and its associated metadata per
Arrow specification
JSON Reader
An ordered sequence of Field with optional metadata.
ChunkedArray
Create a new DataFrame by reading a csv file.
Write a DataFrame to csv.
Read Arrows IPC format into a DataFrame
Write a DataFrame to Arrow’s IPC format
Lazy abstraction over an eager DataFrame.
It really is an abstraction over a logical plan. The methods of this struct will incrementally
modify a logical plan until output is requested (via collect)
Utility struct for lazy groupby operation.
Maps a logical type to a a chunked array implementation of the physical type. This saves a lot of compiler bloat and allows us to reuse functionality.
Wrapper type that indicates that the inner type is not equal to anything
Just a wrapper structure. Useful for certain impl specializations
This is for instance use to implement
impl<T> FromIterator<T::Native> for NoNull<ChunkedArray<T>>
as Option<T::Native> was already implemented:
impl<T> FromIterator<Option<T::Native>> for ChunkedArray<T>
The literal Null
State of the allowed optimizations
Read Apache parquet format into a DataFrame.
Write a DataFrame to parquet format
Wrapper struct that allow us to use a PhysicalExpr in polars-io.
JSON file reader builder
A two-dimensional dataset with a number of
columns ([Array]) and rows and defined Schema.
Series
Intermediate state of when(..).then(..).otherwise(..) expr.
Intermediate state of when(..).then(..).otherwise(..) expr.
Intermediate state of chain when then exprs.
Enums
The set of supported logical types.
Each variant uniquely identifies a logical type, which define specific semantics to the data (e.g. how it should be represented).
Each variant has a corresponding [PhysicalType], obtained via DataType::to_physical_type,
which declares the in-memory representation of data.
The DataType::Extension is special in that it augments a DataType with metadata to support custom types.
Use to_logical_type to desugar such type and return its correspoding logical type.
Queries consists of multiple expressions.
One of the three arguments allowed in unchecked_take
The time units defined in Arrow.
Traits
Argmin/ Argmax
Aggregation operations
Aggregations that return Series of unit length. Those can be used in broadcasting operations.
Fastest way to do elementwise operations on a ChunkedArray
Apply kernels on the arrow array chunks in a ChunkedArray.
Cast ChunkedArray<T> to ChunkedArray<N>
Compare Series
and ChunkedArray’s and get a boolean mask that
can be used to filter rows.
Create a new ChunkedArray filled with values at that index.
Explode/ flatten a
Replace None values with various strategies
Replace None values with a value
Filter values by a boolean mask.
Fill a ChunkedArray with one value.
Find local minima/ maxima
Reverse a ChunkedArray
This differs from ChunkWindowCustom and ChunkWindow
by not using a fold aggregator, but reusing a Series wrapper and calling Series aggregators.
This likely is a bit slower than ChunkWindow
Create a ChunkedArray with new values by index or by boolean mask.
Note that these operations clone data. This is however the only way we can modify at mask or
index level as the underlying Arrow arrays are immutable.
Shift the values of a ChunkedArray by a number of periods.
Sort operations on ChunkedArray.
Fast access by index.
Traverse and collect every nth element
Get unique values in a ChunkedArray
Variance and standard deviation aggregation.
Combine 2 ChunkedArrays based on some predicate.
Executors will evaluate physical expressions and collect them in a DataFrame.
Trait for ChunkedArrays that don’t have null values.
The result is the most efficient implementation Iterator, according to the number of chunks.
Create a type that implements a faster TakeRandom.
Mask the first unique values as true
Check if element is member of list array
Mask the last unique values as true
Take a DataFrame and evaluate the expressions. Implement this for Column, lt, eq, etc
A type that implements this transforms a LogicalPlan to a physical plan.
A PolarsIterator is an iterator over a ChunkedArray which contains polars types. A PolarsIterator
must implement ExactSizeIterator and DoubleEndedIterator.
Values need to implement this so that they can be stored into a Series and DataFrame
Any type that is not nested
Repeat the values n times.
A wrapper trait for any binary closure Fn(Series, Series) -> Result<Series>
A wrapper trait for any closure Fn(Vec<Series>) -> Result<Series>
Concat the values into a string array.
Random access
Functions
Evaluate all the expressions with a bitwise and
Evaluate all the expressions with a bitwise or
Apply a function/closure over the groups of multiple columns. This should only be used in a groupby aggregation.
Find the mean of all the values in this Expression.
Create a Column Expression based on a column name.
Select multiple columns by name
Count the number of values in this Expression.
Select multiple columns by dtype.
Select multiple columns by dtype.
Accumulate over multiple columns horizontally / row wise.
IsNotNull expression.
Create a Literal Expression from L
Apply a closure on the two columns that are evaluated from Expr a and Expr b.
Binary function where the output type is determined at runtime when the schema is known.
Apply a function/closure over multiple columns once the logical plan get executed.
Apply a function/closure over multiple columns once the logical plan get executed.
Find the maximum of all the values in this Expression.
Get the the minimum value per row
Find the mean of all the values in this Expression.
Find the median of all the values in this Expression.
Find the minimum of all the values in this Expression.
Get the the minimum value per row
Find a specific quantile of all the values in this Expression.
Create a range literal.
Sum all the values in this Expression.
Get the the sum of the values per row
Start a when-then-otherwise expression
Type Definitions
AllowedOptimizations
Typedef for a std::result::Result of an ArrowError.
Dummy type, we need to instantiate all generic types, so we fill one with a dummy.