Expr.Array (ArrayOps)

Namespace: Polars.CSharp

Offers methods for accessing fields within array columns.

Instance Methods

Agg

Run any polars aggregation expression against the arrays’ elements.

public Expr Agg(Expr expr)

Parameters

Name	Type	Description
expr	Expr	-

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All

Check if all elements in the sub-array are true.

public Expr All(bool ignoreNulls = true)

Parameters

Name	Type	Description
ignoreNulls	bool	-

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Any

Check if any element in the sub-array is true.

public Expr Any(bool ignoreNulls = true)

Parameters

Name	Type	Description
ignoreNulls	bool	-

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ArgMax

Get the index of the maximum value in every sub-array.

public Expr ArgMax()

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ArgMin

Get the index of the minimum value in every sub-array.

public Expr ArgMin()

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Concat

Concat this Array expression with other Array expressions.

public Expr Concat(params Expr[] others)

Parameters

Name	Type	Description
others	Expr[]	Other list expressions to append.

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Contains

Check if sub-array contains a specific item.

public Expr Contains(Expr item, bool nullsEqual = false)

Parameters

Name	Type	Description
item	Expr	-
nullsEqual	bool	-

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CountMatches

Count how often the value produced by element occurs.

public Expr CountMatches(Expr element)

Parameters

Name	Type	Description
element	Expr	An expression that produces a single value

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Eval

Run any polars expression against the arrays’ elements.

public Expr Eval(Expr expr, bool asList = false)

Parameters

Name	Type	Description
expr	Expr	Expression to run. Note that you can select an element with pl.element()
asList	bool	Collect the resulting data as a list. This allows for expressions which output a variable amount of data.

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Explode

Explode the array column into multiple rows. The resulting Series will be longer than the original.

public Expr Explode(bool emptyAsNull = true, bool keepNulls = true)

Parameters

Name	Type	Description
emptyAsNull	bool	-
keepNulls	bool	-

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First

Get the first value of the sub-arrays.

public Expr First()

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Get

Get element at index from every sub-array.

public Expr Get(long index, bool nullOnOob = true)

Parameters

Name	Type	Description
index	long	-
nullOnOob	bool	-

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Join

Join elements with a separator.

public Expr Join(string separator, bool ignoreNulls = true)

Parameters

Name	Type	Description
separator	string	-
ignoreNulls	bool	-

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Last

Get the last value of the sub-arrays.

public Expr Last()

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Len

Return the number of elements in each array.

public Expr Len()

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Max

Compute the max value of every sub-array.

public Expr Max()

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Mean

Compute the mean of every sub-array.

public Expr Mean()

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Median

Compute the median of every sub-array.

public Expr Median()

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Min

Compute the min value of every sub-array.

public Expr Min()

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NUnique

Count the number of unique values in every sub-arrays.

public Expr NUnique()

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Reverse

Reverse elements in every sub-array.

public Expr Reverse()

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Sort

Sort elements in every sub-array.

public Expr Sort(bool descending = false, bool nullsLast = false, bool maintainOrder = false)

Parameters

Name	Type	Description
descending	bool	-
nullsLast	bool	-
maintainOrder	bool	-

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Std

Compute the standard deviation of every sub-array.

public Expr Std(byte ddof = 1)

Parameters

Name	Type	Description
ddof	byte	-

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Sum

Compute the sum of every sub-array.

public Expr Sum()

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ToList

Cast to variable-size List.

public Expr ToList()

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ToStruct

Convert array to struct.

Convert array to a struct using a function to generate field names dynamically.

public Expr ToStruct(params string[] fields)
public Expr ToStruct(Func<int, string> nameGenerator, int fieldCount)

Parameters

Name	Type	Description
fields	string[]	Desired field names
nameGenerator	Func<int, string>	A function that takes an index and returns a string.
fieldCount	int	The expected number of fields to generate.

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Unique

Get unique elements in every sub-array.

public Expr Unique(bool maintainOrder = false)

Parameters

Name	Type	Description
maintainOrder	bool	-

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Var

Compute the variance of every sub-array.

public Expr Var(byte ddof = 1)

Parameters

Name	Type	Description
ddof	byte	-

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