emzed.table.expressions module

class emzed.table.expressions.Apply(model, function, args, ignore_nones)

Bases: Expression

class emzed.table.expressions.BinaryInfix(operator, left, right)

Bases: _Binary

class emzed.table.expressions.BinaryPrefix(operator, left, right)

Bases: _Binary

class emzed.table.expressions.ColumnAccessor(model, col_name, col_type, db_col_name, access_name)

Bases: Expression

count_not_none()

lookup(other_key, other_value)

to_list()

unique_value()

unique_values()

class emzed.table.expressions.Contains(left, right)

Bases: _StringLike

class emzed.table.expressions.EndsWith(left, right)

Bases: _StringLike

class emzed.table.expressions.Expression

Bases: ABC

abs()

approx_equal(other, atol, rtol)

compatible_with_sql_update = True

contains(other)

Column expression to evaluate if value contains the specified string, element-wise.

: param: other: String defining search sequence.

copy()

endswith(other)

Column expression to evaluate if value ends with the specified postfix, element-wise.

: param: other: str defining postfix

floor()

Return the floor of the column values, element-wise.

Example:

a
float
-----
-1.70
-1.50
-0.20
0.20
1.50
1.70
2.00

t.add_column('b ', t.a.floor(), float)

results

a      b
float  float
-----  -----
-1.70  -1.00
-1.50  -1.00
-0.20   0.00
0.20   0.00
1.50   1.00
1.70   1.00
2.00   2.00

see also max().

if_not_none_else(right)

in_range(left, right)

is_in(values)

is_none()

expression to evaluate None values in column.

Since == operation is not possible with None it replaces Python expression if value is None:

Example: .. code-block:: python

t.replace_column(t.a.is_none().then_else(1e-10, t.a), float)

is_not_none()

Column expression to evaluate values different from None.

Since != operation is not possible with None it replaces Python expression if value is not None:.

Example:

t1 = t.filter(t.a.is_not_none())

max()

table.column expression evaluating column to its maximal value.

Examples: Given table t

a
float
-----
2.00
4.30
1.50

t.add_column(‘b ‘, t.a.max(), float)

results

a      b
float  float
-----  -----
2.00   4.30
4.30   4.30
1.50   4.30

and

t.a.max().eval() == max(t.a) == 4.3

min()

table.column expression evaluating column to its minimal value, element-wise.

Use analogous to max().

round(digits=0)

expression to round column values to the given number of digits, element-wise.

Parameters:

digits – Number of digits applied for rounding.

Use analogous to max().

startswith(other)

Column expression to evaluate if value starts with the specified prefix, element-wise.

: param: other: str defining prefix

Example: .. parsed-literal:

a
str
---------
hello
hey
you, hey?

t.add_column('b ', t.a.startswith('he'), bool)

results

a          b
str        bool
---------  -----
hello      True
hey        True
you, hey?  False

then_else(then, else_)

expression to perform if then else operations on Table Column.

Parameters:

• then – column or value returned if condition is True.

• else – column or value returned if condition is False.

Examples: 1) .. parsed-literal:

a
float
-----
2.00
4.30
1.50

t.add_column(‘b ‘, (t.a>2).then_else(t.a, -1.0), float)

results:

a      b
float  float
-----  -----
2.00  -1.00
4.30   4.30
1.50  -1.00

a
bool
-----
True
False
True

t.add_column('b ', t.a.then_else('green', 'red'), str)

retults:

a b bool str —– —– True green False red True green

class emzed.table.expressions.FunctionWrapper(function, model, ignore_nones, args)

Bases: object

reconstruct_all_function_args(db_args)

class emzed.table.expressions.IsIn(expression, values)

Bases: Expression

class emzed.table.expressions.Lookup(left_key, right_key, right_value)

Bases: Expression

class emzed.table.expressions.NonAlgebraicColumnAccessor(model, col_name, col_type, db_col_name, access_name)

Bases: ColumnAccessor

class emzed.table.expressions.Predicate(expression, sql_term)

Bases: Expression

class emzed.table.expressions.Reduction(expression, name, sql_template)

Bases: Unary

eval()

class emzed.table.expressions.StartsWith(left, right)

Bases: _StringLike

class emzed.table.expressions.ThenElse(condition, then, else_)

Bases: Expression

class emzed.table.expressions.Unary(expression, name, sql_template)

Bases: Expression

eval()

class emzed.table.expressions.Value(value)

Bases: Expression

emzed.table.expressions.column_accessor(model, col_name, col_type, db_col_name, access_name)