4.3.2.4. List functions
The following functions support list operations.
In FEEL, the index of the first element in a list is 1
. The index of the last element in a list can be identified as -1
.
- list contains( list, element )
Returns
true
if the list contains the element.表4.28 Parameters
Parameter Type list
list
element
Any type, including null
Example
list contains( [1,2,3], 2 ) = true
- count( list )
Counts the elements in the list.
表4.29 Parameters
Parameter Type list
list
Examples
count( [1,2,3] ) = 3 count( [] ) = 0 count( [1,[2,3]] ) = 2
- min( list )
Returns the minimum comparable element in the list.
表4.30 Parameters
Parameter Type list
list
Alternative signature
min( e1, e2, ..., eN )
Examples
min( [1,2,3] ) = 1 min( 1 ) = 1 min( [1] ) = 1
- max( list )
Returns the maximum comparable element in the list.
表4.31 Parameters
Parameter Type list
list
Alternative signature
max( e1, e2, ..., eN )
Examples
max( 1,2,3 ) = 3 max( [] ) = null
- sum( list )
Returns the sum of the numbers in the list.
表4.32 Parameters
Parameter Type list
list
ofnumber
elementsAlternative signature
sum( n1, n2, ..., nN )
Examples
sum( [1,2,3] ) = 6 sum( 1,2,3 ) = 6 sum( 1 ) = 1 sum( [] ) = null
- mean( list )
Calculates the average (arithmetic mean) of the elements in the list.
表4.33 Parameters
Parameter Type list
list
ofnumber
elementsAlternative signature
mean( n1, n2, ..., nN )
Examples
mean( [1,2,3] ) = 2 mean( 1,2,3 ) = 2 mean( 1 ) = 1 mean( [] ) = null
- all( list )
Returns
true
if all elements in the list are true.表4.34 Parameters
Parameter Type list
list
ofboolean
elementsAlternative signature
all( b1, b2, ..., bN )
Examples
all( [false,null,true] ) = false all( true ) = true all( [true] ) = true all( [] ) = true all( 0 ) = null
- any( list )
Returns
true
if any element in the list is true.表4.35 Parameters
Parameter Type list
list
ofboolean
elementsAlternative signature
any( b1, b2, ..., bN )
Examples
any( [false,null,true] ) = true any( false ) = false any( [] ) = false any( 0 ) = null
- sublist( list, start position, length? )
Returns the sublist from the start position, limited to the length elements.
表4.36 Parameters
Parameter Type list
list
start position
number
length
(Optional)number
Example
sublist( [4,5,6], 1, 2 ) = [4,5]
- append( list, item )
Creates a list that is appended to the item or items.
表4.37 Parameters
Parameter Type list
list
item
Any type
Example
append( [1], 2, 3 ) = [1,2,3]
- concatenate( list )
Creates a list that is the result of the concatenated lists.
表4.38 Parameters
Parameter Type list
list
Example
concatenate( [1,2],[3] ) = [1,2,3]
- insert before( list, position, newItem )
Creates a list with the
newItem
inserted at the specified position.表4.39 Parameters
Parameter Type list
list
position
number
newItem
Any type
Example
insert before( [1,3],1,2 ) = [2,1,3]
- remove( list, position )
Creates a list with the removed element excluded from the specified position.
表4.40 Parameters
Parameter Type list
list
position
number
Example
remove( [1,2,3], 2 ) = [1,3]
- reverse( list )
Returns a reversed list.
表4.41 Parameters
Parameter Type list
list
Example
reverse( [1,2,3] ) = [3,2,1]
- index of( list, match )
Returns indexes matching the element.
Parameters
-
list
of typelist
-
match
of any type
表4.42 Parameters
Parameter Type list
list
match
Any type
Example
index of( [1,2,3,2],2 ) = [2,4]
-
- union( list )
Returns a list of all the elements from multiple lists and excludes duplicates.
表4.43 Parameters
Parameter Type list
list
Example
union( [1,2],[2,3] ) = [1,2,3]
- distinct values( list )
Returns a list of elements from a single list and excludes duplicates.
表4.44 Parameters
Parameter Type list
list
Example
distinct values( [1,2,3,2,1] ) = [1,2,3]
- flatten( list )
Returns a flattened list.
表4.45 Parameters
Parameter Type list
list
Example
flatten( [[1,2],[[3]], 4] ) = [1,2,3,4]
- product( list )
Returns the product of the numbers in the list.
表4.46 Parameters
Parameter Type list
list
ofnumber
elementsAlternative signature
product( n1, n2, ..., nN )
Examples
product( [2, 3, 4] ) = 24 product( 2, 3, 4 ) = 24
- median( list )
Returns the median of the numbers in the list. If the number of elements is odd, the result is the middle element. If the number of elements is even, the result is the average of the two middle elements.
表4.47 Parameters
Parameter Type list
list
ofnumber
elementsAlternative signature
median( n1, n2, ..., nN )
Examples
median( 8, 2, 5, 3, 4 ) = 4 median( [6, 1, 2, 3] ) = 2.5 median( [ ] ) = null
- stddev( list )
Returns the standard deviation of the numbers in the list.
表4.48 Parameters
Parameter Type list
list
ofnumber
elementsAlternative signature
stddev( n1, n2, ..., nN )
Examples
stddev( 2, 4, 7, 5 ) = 2.081665999466132735282297706979931 stddev( [47] ) = null stddev( 47 ) = null stddev( [ ] ) = null
- mode( list )
Returns the mode of the numbers in the list. If multiple elements are returned, the numbers are sorted in ascending order.
表4.49 Parameters
Parameter Type list
list
ofnumber
elementsAlternative signature
mode( n1, n2, ..., nN )
Examples
mode( 6, 3, 9, 6, 6 ) = [6] mode( [6, 1, 9, 6, 1] ) = [1, 6] mode( [ ] ) = [ ]