Expressions

daft.expressions.Expression

Expression Constructors

daft.DataFrame.__getitem__	Gets a column from the DataFrame as an Expression (df["mycol"])
daft.expressions.col	Creates an Expression referring to the column with the provided name
daft.expressions.lit	Creates an Expression representing a column with every value set to the provided value

Operators

Numeric

Operations on numbers (floats and integers)

daft.expressions.Expression.__abs__()	Absolute of a numeric expression (abs(expr))
daft.expressions.Expression.__add__(other)	Adds two numeric expressions or concatenates two string expressions (e1 + e2)
daft.expressions.Expression.__sub__(other)	Subtracts two numeric expressions (e1 - e2)
daft.expressions.Expression.__mul__(other)	Multiplies two numeric expressions (e1 * e2)
daft.expressions.Expression.__truediv__(other)	True divides two numeric expressions (e1 / e2)
daft.expressions.Expression.__mod__(other)	Takes the mod of two numeric expressions (e1 % e2)

Logical

Operations on logical expressions (True/False booleans)

daft.expressions.Expression.__invert__()	Inverts a boolean expression (~e)
daft.expressions.Expression.__and__(other)	Takes the logical AND of two boolean expressions (e1 & e2)
daft.expressions.Expression.__or__(other)	Takes the logical OR of two boolean expressions (e1 | e2)
daft.expressions.Expression.if_else(if_true, ...)	Conditionally choose values between two expressions using the current boolean expression as a condition

Comparisons

Comparing expressions and values, returning a logical expression

daft.expressions.Expression.__lt__(other)	Compares if an expression is less than another (e1 < e2)
daft.expressions.Expression.__le__(other)	Compares if an expression is less than or equal to another (e1 <= e2)
daft.expressions.Expression.__eq__(other)	Compares if an expression is equal to another (e1 == e2)
daft.expressions.Expression.__ne__(other)	Compares if an expression is not equal to another (e1 != e2)
daft.expressions.Expression.__gt__(other)	Compares if an expression is greater than another (e1 > e2)
daft.expressions.Expression.__ge__(other)	Compares if an expression is greater than or equal to another (e1 >= e2)
daft.expressions.Expression.is_null()	Checks if values in the Expression are Null (a special value indicating missing data)

Floats

Operations on strings, accessible through the Expression.float method accessor.

Example: e1.float.is_nan()

daft.expressions.expressions.ExpressionFloatNamespace.is_nan()

Checks if values are NaN (a special float value indicating not-a-number)

Strings

Operations on strings, accessible through the Expression.str method accessor.

Example: e1.str.concat(e2)

daft.expressions.expressions.ExpressionStringNamespace.concat(other)	Concatenates two string expressions together
daft.expressions.expressions.ExpressionStringNamespace.contains(substr)	Checks whether each string contains the given pattern in a string column
daft.expressions.expressions.ExpressionStringNamespace.endswith(suffix)	Checks whether each string ends with the given pattern in a string column
daft.expressions.expressions.ExpressionStringNamespace.startswith(prefix)	Checks whether each string starts with the given pattern in a string column
daft.expressions.expressions.ExpressionStringNamespace.length()	Retrieves the length for a UTF-8 string column

Dates

Operations on datetimes, accessible through the Expression.dt method accessor:

Example: e.dt.day()

daft.expressions.expressions.ExpressionDatetimeNamespace.day	Retrieves the day for a datetime column
daft.expressions.expressions.ExpressionDatetimeNamespace.month	Retrieves the month for a datetime column
daft.expressions.expressions.ExpressionDatetimeNamespace.year	Retrieves the year for a datetime column
daft.expressions.expressions.ExpressionDatetimeNamespace.day_of_week	Retrieves the day of the week for a datetime column, starting at 0 for Monday and ending at 6 for Sunday

URLs

Operations on URLs, accessible through the Expression.url method accessor:

Example: e.url.download()

daft.expressions.expressions.ExpressionUrlNamespace.download

Treats each string as a URL, and downloads the bytes contents as a bytes column

Images

Operations on images, accessible through the Expression.image method accessor:

Example: e.image.resize()

daft.expressions.expressions.ExpressionImageNamespace.resize
daft.expressions.expressions.ExpressionImageNamespace.decode

Changing Column Names/Types

daft.expressions.Expression.alias	Gives the expression a new name, which is its column's name in the DataFrame schema and the name by which subsequent expressions can refer to the results of this expression.
daft.expressions.Expression.cast	Casts an expression to the given datatype if possible

Running Python Functions

daft.expressions.Expression.apply

Apply a function on each value in a given expression