Standard Operations

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argmax

Return the value of key when the expression is at its maximum value.

If a where condition is specified, method only considers rows meeting the where condition.

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argmin

Return the value of key when the expression is at its minimum value.

If a where condition is specified, method only considers rows meeting the where condition.

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as_scalar

Convert the expression to a scalar value. Note that the execution of the scalar subquery will fail if the column expression contains more than one value.

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between

Check if this expression is between lower and upper, inclusive.

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cast

Cast expression to indicated data type. Type inputs can include strings, python type annotations, numpy dtypes, pandas dtypes, and pyarrow dtypes.

If try_ is True, then the cast will return null if the cast fails, otherwise it will raise an error.

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coalesce

Return the first non-null value in the expression list.

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collect

Collect the expression into an array.

If a where condition is specified, method only considers rows meeting the where condition.

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combine

Combine the expression into a single string using the specified separator.

If a where condition is specified, method only considers rows meeting the where condition.

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count

Return the number of non-null values in the expression, only including values when the where condition is true.

If distinct is True, then the number of unique values will be returned instead of the total count.

If approx is True and distinct is True, method will use approximate count distinct function, which is faster but less accurate. This is only available for count distinct.

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epoch_seconds

Return the number of seconds since the Unix epoch.

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equivalent

Null-aware version of ==. Returns true if both expressions are equal or both are null.

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first

Return the first value in the expression.

If a where condition is specified, method only considers rows meeting the where condition.

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hash

Compute an integer hash value of the expression.

The hashing function used is dependent on the backend, so usage across dialect will likely return a different number.

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in_

Check if this expression is in the provided set of values. Exists in place of the python in operator because of its requirement to evaluate to a python boolean.

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lag

Return the row located at offset rows before the current row. If no row exists at offset, the default value is returned.

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last

Return the last value in the expression.

If a where condition is specified, method only considers rows meeting the where condition.

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lead

Return the row located at offset rows after the current row. If no row exists at offset, the default value is returned.

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like

This function is modeled after SQL’s LIKE and ILIKE directives. Use % as a multiple-character wildcard or _ as a single-character wildcard.

For regular expressions, use re.search.

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match

Return a value based on the first matching condition in the expression. The default value is returned if no conditions are met, otherwise null is returned.

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max

Return the maximum value of the expression

If a where condition is specified, method only considers rows meeting the where condition.

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mean

Return the mean of the expression

If a where condition is specified, method only considers rows meeting the where condition.

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median

Return the median value of the expression.

If a where condition is specified, method only considers rows meeting the where condition.

If approx is True, method will use the approximate median function, which is faster but less accurate.

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min

Return the minimum value of the expression

If a where condition is specified, method only considers rows meeting the where condition.

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mode

Return the mode value of the expression

If a where condition is specified, method only considers rows meeting the where condition.

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nth

Return the nth value of the expression

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quantile

Return value at the given quantile. If multiple quantiles are specified, then the output will be an array of values.

The output of this method a discrete quantile if the input is an float, otherwise it is a continuous quantile.

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strftime

Format string may depend on the backend, but we try to conform to ANSI strftime.

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sum

Return the sum of the expression

If a where condition is specified, method only considers rows meeting the where condition.

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type

Return the string name of the datatype of the expression.

If db_type is True, then the string will be the name of the datatype in the specific backend (e.g. duckdb), otherwise it will be cross-dialect data type name from Vinyl.