Expression API

DataFrame methods such as select and filter accept one or more logical expressions and there are many functions available for creating logical expressions. These are documented below.

Expressions can be chained together using a fluent-style API:

// create the expression `(a > 6) AND (b < 7)`
col("a").gt(lit(6)).and(col("b").lt(lit(7)))

Identifiers

Function	Notes
col	Reference a column in a dataframe col("a")

Literal Values

Function	Notes
lit	Literal value such as lit(123) or lit("hello")

Boolean Expressions

Function	Notes
and	and(expr1, expr2) or expr1.and(expr2)
or	or(expr1, expr2) or expr1.or(expr2)
not	not(expr) or expr.not()

Bitwise expressions

Function	Notes
bitwise_and	bitwise_and(expr1, expr2) or expr1.bitwise_and(expr2)
bitwise_or	bitwise_or(expr1, expr2) or expr1.bitwise_or(expr2)
bitwise_xor	bitwise_xor(expr1, expr2) or expr1.bitwise_xor(expr2)
bitwise_shift_right	bitwise_shift_right(expr1, expr2) or expr1.bitwise_shift_right(expr2)
bitwise_shift_left	bitwise_shift_left(expr1, expr2) or expr1.bitwise_shift_left(expr2)

Comparison Expressions

Function	Notes
eq	expr1.eq(expr2)
gt	expr1.gt(expr2)
gt_eq	expr1.gt_eq(expr2)
lt	expr1.lt(expr2)
lt_eq	expr1.lt_eq(expr2)
not_eq	expr1.not_eq(expr2)

Math Functions

In addition to the math functions listed here, some Rust operators are implemented for expressions, allowing expressions such as col("a") + col("b") to be used.

Function	Notes
abs(x)	absolute value
acos(x)	inverse cosine
acosh(x)	inverse hyperbolic cosine
asin(x)	inverse sine
asinh(x)	inverse hyperbolic sine
atan(x)	inverse tangent
atanh(x)	inverse hyperbolic tangent
atan2(y, x)	inverse tangent of y / x
cbrt(x)	cube root
ceil(x)	nearest integer greater than or equal to argument
cos(x)	cosine
cosh(x)	hyperbolic cosine
degrees(x)	converts radians to degrees
exp(x)	exponential
factorial(x)	factorial
floor(x)	nearest integer less than or equal to argument
gcd(x, y)	greatest common divisor
isnan(x)	predicate determining whether NaN/-NaN or not
iszero(x)	predicate determining whether 0.0/-0.0 or not
lcm(x, y)	least common multiple
ln(x)	natural logarithm
log(base, x)	logarithm of x for a particular base
log10(x)	base 10 logarithm
log2(x)	base 2 logarithm
nanvl(x, y)	returns x if x is not NaN otherwise returns y
pi()	approximate value of π
power(base, exponent)	base raised to the power of exponent
radians(x)	converts degrees to radians
round(x)	round to nearest integer
signum(x)	sign of the argument (-1, 0, +1)
sin(x)	sine
sinh(x)	hyperbolic sine
sqrt(x)	square root
tan(x)	tangent
tanh(x)	hyperbolic tangent
trunc(x)	truncate toward zero

Math functions usage notes:

Unlike to some databases the math functions in Datafusion works the same way as Rust math functions, avoiding failing on corner cases e.g

❯ select log(-1), log(0), sqrt(-1);
+----------------+---------------+-----------------+
| log(Int64(-1)) | log(Int64(0)) | sqrt(Int64(-1)) |
+----------------+---------------+-----------------+
| NaN            | -inf          | NaN             |
+----------------+---------------+-----------------+

Bitwise Operators

Operator	Notes
&	Bitwise AND => (expr1 & expr2)
|	Bitwise OR => (expr1 | expr2)
#	Bitwise XOR => (expr1 # expr2)
<<	Bitwise left shift => (expr1 << expr2)
>>	Bitwise right shift => (expr1 << expr2)

Conditional Expressions

Function	Notes
coalesce	Returns the first of its arguments that is not null. Null is returned only if all arguments are null. It is often used to substitute a default value for null values when data is retrieved for display.
case	CASE expression. Example: case(expr).when(expr, expr).when(expr, expr).otherwise(expr).end().
nullif	Returns a null value if value1 equals value2; otherwise it returns value1. This can be used to perform the inverse operation of the coalesce expression.

String Expressions

Function	Notes
ascii(character)	Returns a numeric representation of the character (character). Example: ascii('a') -> 97
bit_length(text)	Returns the length of the string (text) in bits. Example: bit_length('spider') -> 48
btrim(text, characters)	Removes all specified characters (characters) from both the beginning and the end of the string (text). Example: btrim('aabchelloccb', 'abc') -> hello
char_length(text)	Returns number of characters in the string (text). The same as character_length and length. Example: character_length('lion') -> 4
character_length(text)	Returns number of characters in the string (text). The same as char_length and length. Example: char_length('lion') -> 4
concat(value1, [value2 [, …]])	Concatenates the text representations (value1, [value2 [, ...]]) of all the arguments. NULL arguments are ignored. Example: concat('aaa', 'bbc', NULL, 321) -> aaabbc321
concat_ws(separator, value1, [value2 [, …]])	Concatenates the text representations (value1, [value2 [, ...]]) of all the arguments with the separator (separator). NULL arguments are ignored. concat_ws('/', 'path', 'to', NULL, 'my', 'folder', 123) -> path/to/my/folder/123
chr(integer)	Returns a character by its numeric representation (integer). Example: chr(90) -> 8
initcap	Converts the first letter of each word to upper case and the rest to lower case. Example: initcap('hi TOM') -> Hi Tom
left(text, number)	Returns a certain number (number) of first characters (text). Example: left('like', 2) -> li
length(text)	Returns number of characters in the string (text). The same as character_length and char_length. Example: length('lion') -> 4
lower(text)	Converts all characters in the string (text) into lower case. Example: lower('HELLO') -> hello
lpad(text, length, [, fill])	Extends the string to length (length) by prepending the characters (fill) (a space by default). Example: lpad('bb', 5, 'a') → aaabb
ltrim(text, text)	Removes all specified characters (characters) from the beginning of the string (text). Example: ltrim('aabchelloccb', 'abc') -> helloccb
md5(text)	Computes the MD5 hash of the argument (text).
octet_length(text)	Returns number of bytes in the string (text).
repeat(text, number)	Repeats the string the specified number of times. Example: repeat('1', 4) -> 1111
replace(string, from, to)	Replaces a specified string (from) with another specified string (to) in the string (string). Example: replace('Hello', 'replace', 'el') -> Hola
reverse(text)	Reverses the order of the characters in the string (text). Example: reverse('hello') -> olleh
right(text, number)	Returns a certain number (number) of last characters (text). Example: right('like', 2) -> ke
rpad(text, length, [, fill])	Extends the string to length (length) by prepending the characters (fill) (a space by default). Example: rpad('bb', 5, 'a') → bbaaa
rtrim	Removes all specified characters (characters) from the end of the string (text). Example: rtrim('aabchelloccb', 'abc') -> aabchello
digest(input, algorithm)	Computes the binary hash of input, using the algorithm.
split_part(string, delimiter, index)	Splits the string (string) based on a delimiter (delimiter) and picks out the desired field based on the index (index).
starts_with(string, prefix)	Returns true if the string (string) starts with the specified prefix (prefix). If not, it returns false. Example: starts_with('Hi Tom', 'Hi') -> true
strpos	Finds the position from where the substring matches the string
substr(string, position, [, length])	Returns substring from the position (position) with length (length) characters in the string (string).
translate(string, from, to)	Replaces the characters in from with the counterpart in to. Example: translate('abcde', 'acd', '15') -> 1b5e
trim(string)	Removes all characters, space by default from the string (string)
upper	Converts all characters in the string into upper case. Example: upper('hello') -> HELLO

Array Expressions

Function	Notes
array_append(array, element)	Appends an element to the end of an array. array_append([1, 2, 3], 4) -> [1, 2, 3, 4]
array_concat(array[, …, array_n])	Concatenates arrays. array_concat([1, 2, 3], [4, 5, 6]) -> [1, 2, 3, 4, 5, 6]
array_has(array, element)	Returns true if the array contains the element array_has([1,2,3], 1) -> true
array_has_all(array, sub-array)	Returns true if all elements of sub-array exist in array array_has_all([1,2,3], [1,3]) -> true
array_has_any(array, sub-array)	Returns true if any elements exist in both arrays array_has_any([1,2,3], [1,4]) -> true
array_dims(array)	Returns an array of the array’s dimensions. array_dims([[1, 2, 3], [4, 5, 6]]) -> [2, 3]
array_element(array, index)	Extracts the element with the index n from the array array_element([1, 2, 3, 4], 3) -> 3
flatten(array)	Converts an array of arrays to a flat array flatten([[1], [2, 3], [4, 5, 6]]) -> [1, 2, 3, 4, 5, 6]
array_length(array, dimension)	Returns the length of the array dimension. array_length([1, 2, 3, 4, 5]) -> 5
array_ndims(array)	Returns the number of dimensions of the array. array_ndims([[1, 2, 3], [4, 5, 6]]) -> 2
array_pop_back(array)	Returns the array without the last element. array_pop_back([1, 2, 3]) -> [1, 2]
array_position(array, element)	Searches for an element in the array, returns first occurrence. array_position([1, 2, 2, 3, 4], 2) -> 2
array_positions(array, element)	Searches for an element in the array, returns all occurrences. array_positions([1, 2, 2, 3, 4], 2) -> [2, 3]
array_prepend(array, element)	Prepends an element to the beginning of an array. array_prepend(1, [2, 3, 4]) -> [1, 2, 3, 4]
array_repeat(element, count)	Returns an array containing element count times. array_repeat(1, 3) -> [1, 1, 1]
array_remove(array, element)	Removes the first element from the array equal to the given value. array_remove([1, 2, 2, 3, 2, 1, 4], 2) -> [1, 2, 3, 2, 1, 4]
array_remove_n(array, element, max)	Removes the first max elements from the array equal to the given value. array_remove_n([1, 2, 2, 3, 2, 1, 4], 2, 2) -> [1, 3, 2, 1, 4]
array_remove_all(array, element)	Removes all elements from the array equal to the given value. array_remove_all([1, 2, 2, 3, 2, 1, 4], 2) -> [1, 3, 1, 4]
array_replace(array, from, to)	Replaces the first occurrence of the specified element with another specified element. array_replace([1, 2, 2, 3, 2, 1, 4], 2, 5) -> [1, 5, 2, 3, 2, 1, 4]
array_replace_n(array, from, to, max)	Replaces the first max occurrences of the specified element with another specified element. array_replace_n([1, 2, 2, 3, 2, 1, 4], 2, 5, 2) -> [1, 5, 5, 3, 2, 1, 4]
array_replace_all(array, from, to)	Replaces all occurrences of the specified element with another specified element. array_replace_all([1, 2, 2, 3, 2, 1, 4], 2, 5) -> [1, 5, 5, 3, 5, 1, 4]
array_slice(array, index)	Returns a slice of the array. array_slice([1, 2, 3, 4, 5, 6, 7, 8], 3, 6) -> [3, 4, 5, 6]
array_to_string(array, delimiter)	Converts each element to its text representation. array_to_string([1, 2, 3, 4], ',') -> 1,2,3,4
cardinality(array)	Returns the total number of elements in the array. cardinality([[1, 2, 3], [4, 5, 6]]) -> 6
make_array(value1, [value2 [, …]])	Returns an Arrow array using the specified input expressions. make_array(1, 2, 3) -> [1, 2, 3]
trim_array(array, n)	Deprecated

Regular Expressions

Function	Notes
regexp_match	Matches a regular expression against a string and returns matched substrings.
regexp_replace	Replaces strings that match a regular expression

Temporal Expressions

Function	Notes
date_part	Extracts a subfield from the date.
date_trunc	Truncates the date to a specified level of precision.
from_unixtime	Returns the unix time in format.
to_timestamp	Converts a string to a Timestamp(_, _)
to_timestamp_millis	Converts a string to a Timestamp(Milliseconds, None)
to_timestamp_micros	Converts a string to a Timestamp(Microseconds, None)
to_timestamp_seconds	Converts a string to a Timestamp(Seconds, None)
now()	Returns current time.

Other Expressions

Function	Notes
array([value1, …])	Returns an array of fixed size with each argument ([value1, ...]) on it.
in_list(expr, list, negated)	Returns true if (expr) belongs or not belongs (negated) to a list (list), otherwise returns false.
random()	Returns a random value from 0 (inclusive) to 1 (exclusive).
sha224(text)	Computes the SHA224 hash of the argument (text).
sha256(text)	Computes the SHA256 hash of the argument (text).
sha384(text)	Computes the SHA384 hash of the argument (text).
sha512(text)	Computes the SHA512 hash of the argument (text).
to_hex(integer)	Converts the integer (integer) to the corresponding hexadecimal string.

Aggregate Functions

Function	Notes
avg(expr)	Сalculates the average value for expr.
approx_distinct(expr)	Calculates an approximate count of the number of distinct values for expr.
approx_median(expr)	Calculates an approximation of the median for expr.
approx_percentile_cont(expr, percentile)	Calculates an approximation of the specified percentile for expr.
approx_percentile_cont_with_weight(expr, weight_expr, percentile)	Calculates an approximation of the specified percentile for expr and weight_expr.
bit_and(expr)	Computes the bitwise AND of all non-null input values for expr.
bit_or(expr)	Computes the bitwise OR of all non-null input values for expr.
bit_xor(expr)	Computes the bitwise exclusive OR of all non-null input values for expr.
bool_and(expr)	Returns true if all non-null input values (expr) are true, otherwise false.
bool_or(expr)	Returns true if any non-null input value (expr) is true, otherwise false.
count(expr)	Returns the number of rows for expr.
count_distinct	Creates an expression to represent the count(distinct) aggregate function
cube(exprs)	Creates a grouping set for all combination of exprs
grouping_set(exprs)	Create a grouping set.
max(expr)	Finds the maximum value of expr.
median(expr)	Сalculates the median of expr.
min(expr)	Finds the minimum value of expr.
rollup(exprs)	Creates a grouping set for rollup sets.
sum(expr)	Сalculates the sum of expr.

Subquery Expressions

Function	Notes
exists	Creates an EXISTS subquery expression
in_subquery	df1.filter(in_subquery(col("foo"), df2))? is the equivalent of the SQL WHERE foo IN <df2>
not_exists	Creates a NOT EXISTS subquery expression
not_in_subquery	Creates a NOT IN subquery expression
scalar_subquery	Creates a scalar subquery expression

User-Defined Function Expressions

Function	Notes
create_udf	Creates a new UDF with a specific signature and specific return type.
create_udaf	Creates a new UDAF with a specific signature, state type and return type.

previous

DataFrame API

next

SQL Reference