pydeephaven.table

class Table(session, ticket, schema_header=b'', size=None, is_static=None, schema=None)[source]

Bases: pydeephaven._table_interface.TableInterface

A Table object represents a reference to a table on the server. It is the core data structure of Deephaven and supports a rich set of operations such as filtering, sorting, aggregating, joining, snapshotting etc.

Note, an application should never instantiate a Table object directly. Table objects are always provided through factory methods such as Session.empty_table(), or import/export methods such as Session.import_table(), open_table(), or any of the Table operations.

is_closed

check if the table has been closed on the server

Type

bool

agg_by(agg, by)

Perform a Combined Aggregation operation on the table and return the result table.

Parameters
  • agg (ComboAggregation) – the combined aggregation definition

  • by (List[str]) – the group-by column names

Returns

a Table object

Raises

DHError

aj(table, on, joins=[], match_rule=<MatchRule.LESS_THAN_EQUAL: 0>)

Perform a as-of join between this table as the left table and another table as the right table) and returns the result table.

Parameters
  • table (Table) – the right-table of the join

  • on (List[str]) – the columns to match, can be a common name or an equal expression, i.e. “col_a = col_b” for different column names

  • joins (List[str], optional) – a list of the columns to be added from the right table to the result table, can be renaming expressions, i.e. “new_col = col”; default is empty

  • match_rule (MatchRule, optional) – the match rule for the as-of join, default is LESS_THAN_EQUAL

Returns

a Table object

Raises

DHError

avg_by(by=[])

Perform avg-by aggregation on the table and return the result table. Columns not used in the grouping must be of numeric types.

Parameters

by (List[str], optional) – the group-by column names, default is empty

Returns

a Table object

Raises

DHError

close()[source]

Close the table reference on the server.

Raises

DHError

Return type

None

count(col)

Count the number of values in the specified column on the table and return the result in a table with one row and one column.

Parameters

col (str) – the name of the column whose values to be counted

Returns

a Table object

Raises

DHError

count_by(col, by=[])

Perform count-by aggregation on the table and return the result table. The count of each group is stored in a new column named after the ‘col’ parameter.

Parameters
  • col (str) – the name of the column to store the counts

  • by (List[str], optional) – the group-by column names, default is empty

Returns

a Table object

Raises

DHError

drop_columns(cols)

Drop the specified columns from the table and return the result table.

Parameters

cols (List[str]) – the list of column names

Returns

a Table object

Raises

DHError

exact_join(table, on, joins=[])

Perform a exact-join between this table as the left table and another table as the right table) and returns the result table.

Parameters
  • table (Table) – the right-table of the join

  • on (List[str]) – the columns to match, can be a common name or an equal expression, i.e. “col_a = col_b” for different column names

  • joins (List[str], optional) – a list of the columns to be added from the right table to the result table, can be renaming expressions, i.e. “new_col = col”; default is empty

Returns

a Table object

Raises

DHError

first_by(by=[])

Perform First-by aggregation on the table and return the result table which contains the first row of each distinct group.

Parameters

by (List[str], optional) – the group-by column names, default is empty

Returns

a Table object

Raises

DHError

group_by(by=[])

Perform a group-by aggregation on the table and return the result table. After the operation, the columns not in the group-by columns become array-type.

If no group-by column is given,the content of each column is grouped into its own array.

Parameters

by (List[str], optional) – the group-by column names; default is empty

Returns

a Table object

Raises

DHError

head(num_rows)

Perform a head operation on the table and return the result table.

Parameters

num_rows (int) – the number of rows at the head of table

Returns

a Table object

Raises

DHError

head_by(num_rows, by)

Perform a head-by aggregation on the table and return the result table.

Parameters
  • num_rows (int) – the number of rows at the beginning of each group

  • by (List[str]) – the group-by column names

Returns

a Table object

Raises

DHError

join(table, on=[], joins=[], reserve_bits=10)

Perform a cross-join between this table as the left table and another table as the right table) and returns the result table.

Parameters
  • table (Table) – the right-table of the join

  • on (List[str]) – the columns to match, can be a common name or an equal expression, i.e. “col_a = col_b” for different column names

  • joins (List[str], optional) – a list of the columns to be added from the right table to the result table, can be renaming expressions, i.e. “new_col = col”; default is empty

  • reserve_bits (int, optional) – the number of bits of key-space to initially reserve per group; default is 10

Returns

a Table object

Raises

DHError

last_by(by=[])

Perform last-by aggregation on the table and return the result table which contains the last row of each distinct group.

Parameters

by (List[str], optional) – the group-by column names, default is empty

Returns

a Table object

Raises

DHError

lazy_update(formulas)

Perform a lazy-update operation on the table and return the result table.

Parameters

formulas (List[str]) – the column formulas

Returns

a Table object

Raises

DHError

max_by(by=[])

Perform max-by aggregation on the table and return the result table. Columns not used in the grouping must be of numeric types.

Parameters

by (List[str], optional) – the group-by column names, default is empty

Returns

a Table object

Raises

DHError

median_by(by=[])

Perform median-by aggregation on the table and return the result table. Columns not used in the grouping must be of numeric types.

Parameters

by (List[str], optional) – the group-by column names, default is empty

Returns

a Table object

Raises

DHError

min_by(by=[])

Perform min-by aggregation on the table and return the result table. Columns not used in the grouping must be of numeric types.

Parameters

by (List[str], optional) – the group-by column names, default is empty

Returns

a Table object

Raises

DHError

natural_join(table, on, joins=[])

Perform a natural-join between this table as the left table and another table as the right table) and returns the result table.

Parameters
  • table (Table) – the right-table of the join

  • on (List[str]) – the columns to match, can be a common name or an equal expression, i.e. “col_a = col_b” for different column names

  • joins (List[str], optional) – a list of the columns to be added from the right table to the result table, can be renaming expressions, i.e. “new_col = col”; default is empty

Returns

a Table object

Raises

DHError

raj(table, on, joins=[], match_rule=<MatchRule.GREATER_THAN_EQUAL: 2>)

Perform a reverse as-of join between this table as the left table and another table as the right table) and returns the result table.

Parameters
  • table (Table) – the right-table of the join

  • on (List[str]) – the columns to match, can be a common name or an equal expression, i.e. “col_a = col_b” for different column names

  • joins (List[str], optional) – a list of the columns to be added from the right table to the result table, can be renaming expressions, i.e. “new_col = col”; default is empty

  • match_rule (MatchRule, optional) – the match rule for the as-of join, default is GREATER_THAN_EQUAL

Returns

a Table object

Raises

DHError

select(formulas=[])

Perform a select operation on the table and return the result table.

Parameters

formulas (List[str], optional) – the column formulas, default is empty

Returns

a Table object

Raises

DHError

select_distinct(cols=[])

Perform a select-distinct operation on the table and return the result table.

Parameters

cols (List[str], optional) – the list of column names, default is empty

Returns

a Table object

Raises

DHError

snapshot()[source]

Take a snapshot of the table and return a pyarrow Table.

Return type

Table

Returns

a pyarrow.Table

Raises

DHError

sort(order_by, order=[])

Perform a sort operation on the table and return the result table.

Parameters
  • order_by (List[str]) – the names of the columns to be sorted on

  • order (List[SortDirection], optional) – the corresponding sort directions for each sort column, default is empty. In the absence of explicit sort directions, data will be sorted in the ascending order.

Returns

a Table object

Raises

DHError

std_by(by=[])

Perform std-by aggregation on the table and return the result table. Columns not used in the grouping must be of numeric types.

Parameters

by (List[str]) – the group-by column names

Returns

a Table object

Raises

DHError

sum_by(by=[])

Perform sum-by aggregation on the table and return the result table. Columns not used in the grouping must be of numeric types.

Parameters

by (List[str]) – the group-by column names

Returns

a Table object

Raises

DHError

tail(num_rows)

Perform a tail operation on the table and return the result table.

Parameters

num_rows (int) – the number of rows at the end of table

Returns

a Table object

Raises

DHError

tail_by(num_rows, by)

Perform a tail-by aggregation on the table and return the result table.

Parameters
  • num_rows (int) – the number of rows at the end of each group

  • by (List[str]) – the group-by column names

Returns

a Table object

Raises

DHError

ungroup(cols=[], null_fill=True)

Perform an ungroup operation on the table and return the result table. The ungroup columns should be of array types.

Parameters
  • cols (List[str], optional) – the names of the array columns, if empty, all array columns will be ungrouped, default is empty

  • null_fill (bool, optional) – indicates whether null should be used to fill missing cells, default is True

Returns

a Table object

Raises

DHError

update(formulas)

Perform an update operation on the table and return the result table.

Parameters

formulas (List[str]) – the column formulas

Returns

a Table object

Raises

DHError

update_view(formulas)

Perform an update-view operation on the table and return the result table.

Parameters

formulas (List[str]) – the column formulas

Returns

a Table object

Raises

DHError

var_by(by=[])

Perform var-by aggregation on the table and return the result table. Columns not used in the grouping must be of numeric types.

Parameters

by (List[str], optional) – the group-by column names, default is empty

Returns

a Table object

Raises

DHError

view(formulas)

Perform a view operation on the table and return the result table.

Parameters

formulas (List[str]) – the column formulas

Returns

a Table object

Raises

DHError

where(filters)

Perform a filter operation on the table and return the result table.

Parameters

filters (List[str]) – a list of filter condition expressions

Returns

a Table object

Raises

DHError