Arrays, Maps, Tuples
Arrays
array_cast
array_cast(element1,element2,..) create a new array with the given elements, e.g. array_cast(1,2) will get [1,2] Please note, the elements should be in the same type, such as array_cast('a','n'), not array_cast('a',0)
length
length(array)
Get the length of the array.
array[index]
You can easily access any element in the array, just using arrayName[index], such as topValues[2]
The first element's index is 1, instead of 0.
index_of
index_of(arr,x) returns the index of x in the array arr. The first element's index is 1. Return 0 if x is not in the array.
array_compact
array_compact(arr) Removes consecutive duplicate elements from an array, e.g. array_compact([1,1,2,2,2,3,4,4,5])returns [1,2,3,4,5]
array_concat
array_concat(array1,array2) Concatenates two arrays into one.
array_difference
array_difference(arr) calculates the difference between adjacent array elements. Returns an array where the first element will be 0, the second is the difference between a[2] - a[1], etc. e.g. array_difference([1,2,3,5])returns [0,1,1,2]
array_distinct
array_distinct(arr) returns an array containing the distinct elements only. e.g. array_distinct([1,1,2,3,3,1])return [1,2,3], while array_compact([1,1,2,3,3,1])returns [1,2,3,1]
array_flatten
array_flatten(array1, array2,..)Converts an array of arrays to a flat array. e.g. array_flatten([[[1]], [[2], [3]]]) returns [1,2,3]
array_string_concat
array_string_concat(arr[, separator]) Concatenates string representations of values listed in the array with the separator. separator is an optional parameter: a constant string, set to an empty string by default.
For example array_string_concat([1,2,3],'-') to get a string 1-2-3
array_join
array_join(an_array) This is a special function. group_array(col) to group the column value from multiple rows to a single value in a row. array_join does the opposite: it can convert one row with an array value to multiple rows.
For example select array_join([10,20]) as v, 'text' as t will get 2 rows
| v | t |
|---|---|
| 10 | text |
| 20 | text |
array_pop_back
array_pop_back(array) removes the last item from the array. e.g. array_pop_back([1,2,3]) returns [1,2]
array_pop_front
array_pop_front(array) removes the first item from the array. e.g. array_pop_front([1,2,3]) returns [2,3]
array_push_back
array_push_back(array, value) adds the value to the array as the last item. e.g. array_push_back([1,2,3],4) returns [1,2,3,4]
array_push_front
array_push_front(array, value) adds the value to the array as the first item. e.g. array_push_front([1,2,3],4) returns [4,1,2,3]
array_product
array_product(array) multiplies elements in the array. e.g. array_product([2,3,4]) returns 24 (2 x 3 x 4)
array_resize
array_resize(array, size [,extender]) changes the length of the array. If sizeis smaller than the current length of the array, the array is truncated. Otherwise, a new array with the specified size is created, filling value with the specified extender. e.g. array_resize([3,4],1) returns [3]. array_resize([3,4],4,5)returns [3,4,5,5]
array_reverse
array_reverse(arr) returns an array with the reversed order of the original array, e.g. array_reverse([1,2,3]) returns [3,2,1]
array_slice
array_slice(arr, offset [,length]) returns a slice of the array. If length is not specified, then slice to the end of the array, e.g. array_slice([1,2,3,4,5],2) returns [2,3,4,5]. If offset is greater than the array length, it returns an empty array []. If length is specified, this is the length of the new array, e.g. array_slice([1,2,3,4,5],2,3) returns [2,3,4]
array_uniq
array_uniq(arr) returns the number of unique values in the array, e.g. array_uniq([1,1,2,3]) returns 3
array_zip
array_zip(arr1,arr2,.. arrN) group elements from different arrays to a new array of tuples. e.g. array_zip([1,2,3],['a','b','c']) returns [(1,'a'),(2,'b'),(3,'c')]
array_all
array_all([func,] array) returns 1(true) or 0(false) if all elements in the array meets the condition. For example, array_all([1,2]) return 1, and array_all([0,0])return 0. You can pass a lambda function to it as the first argument to customize the condition check, such as array_all(x->x%2=0,[2,4,6]) to check whether each element in the array is even. It returns 1.
array_avg
array_avg([func,] array) returns the average value in the array. For example, array_avg([2,6]) return 4. You can pass a lambda function to it as the first argument to apply on each element before calculating the average, such as array_avg(x->x*x,[2,6]) to get the average for 2*2 and 6*6, which is 20.
array_count
array_count([func,] array) returns the number of elements in the array meeting the condition. By default, check whether the value is not 0. e.g. array_count([0,0,1,2]) returns 2. You can pass a lambda function to it as the first argument to apply on each element before calculating the count, such as array_count(x->x>1,[1,2]) to get the number of numbers which is greater than 1, it returns 1.
array_cum_sum
array_cum_sum([func,] array) returns an array of partial sums of elements in the source array (a running sum). e.g. array_cum_sum([1,1,1]) returns [1,2,3]. You can pass a lambda function to it as the first argument to apply on each element before calculating the moving sum, such as array_cum_sum(x->x*x,[1,2]) to get [1,5]
array_exists
array_exists([func,] array) returns 1(true) or 0(false) if any element in the array meet the condition. For example, array_exists([0,1,2]) return 1, and array_exists([0,0])return 0. You can pass a lambda function to it as the first argument to customize the condition check, such as array_exists(x->x%2=0,[2,3,4]) to check whether any element in the array is even. It returns 1. To check whether all elements meet the condition, use array_all
array_filter
array_filter(func, array) returns an array containing only the element that matches the condition of the specified function. e.g. array_filter(x->x%2=0, [1,2,3,4])returns [2,4]
array_first
array_first(func, array) returns the first element that matches the condition of the specified function. e.g. array_first(x->x%2=0, [1,2,3,4])returns 2.
array_first_index
array_first_index(func, array) returns the index of the first element that matches the condition of the specified function. e.g. array_first_index(x->x%2=0, [1,2,3,4])returns 2.
array_last
array_last(func, array) returns the last element that matches the condition of the specified function. e.g. array_last(x->x%2=0, [1,2,3,4])returns 4. If nothing is found, it returns 0.
array_last_index
array_last_index(func, array) returns the index of the last element that matches the condition of the specified function. e.g. array_last_index(x->x%2=0, [1,2,3,4])returns 4. If nothing is found, it returns 0.
array_map
array_map(func, array) applies the function to every element in the array and returns a new array. e.g. array_map(x->x*x,[1,2])returns [1,4]
array_max
Overload 1: array_max(array) returns the maximum value in the array. e.g. array_max([1,2,3]) returns 3
Overload 2: array_max(func, array) apply the function to every element in the array and then returns the maximum value e.g. array_max(x->x*x,[1,2])returns 4
array_min
Overload 1: array_min(array) returns the minimum value in the array. e.g. array_min([1,2,3]) returns 1
Overload 2: array_min(func, array) apply the function to every element in the array and then returns the minimum value e.g. array_min(x->x*x,[1,2])returns 1
array_sort
array_sort([func,] array) sorts the array elements in ascending order. e.g. array_sort([3,2,5,4]) returns [2,3,4,5]. You can pass a lambda function to it as the first argument to apply the function before the sort, e.g. array_sort(x->-x,[3,2,5,4])returns [5,4,3,2]
array_sum
array_sum([func,] array) returns the sum value in the array. For example, array_sum([2,6]) return 8. You can pass a lambda function to it as the first argument to apply on each element before calculating the sum, such as array_sum(x->x*x,[2,6]) to get the sum for 2*2 and 6*6, which is 40.
array_fold
array_fold(lambda_function, arr1, arr2, ..., accumulator) applies a lambda function to one or more equally-sized arrays and collects the result in an accumulator.
For example, array_fold(acc, x -> acc + (x * 2), [1, 2, 3, 4], to_int64(3)) will initialize the accumulator acc as value 3, then for each element in the [1, 2, 3, 4] array, assign it to x and accumulate them together with x*2. So the end result is 3+12+22+32+42=23.
Make sure the return type of lambda function must be the same as the accumulator type.
Maps
map[key]
You can easily access any element in the map, just using mapName[keyName], such as kv['key1']
map_cast
map_cast(array1, array2) to generate a map with keys from array1 and values from array2 (these 2 arrays should be the same size). For example map_cast(['k1','k2'],[91,95]) will get {'k1':91,'k2':95}
Alternatively, you can use map_cast(key1,value1,key2,value2..)
Since Proton v1.4.2, a new extract_key_value_pairs function is added to extract key value pairs from a string to a map.
map_from_arrays
Alias for the above map_cast function.
Tuples
tuple_cast
tuple_cast(item1,item2) to generate a tuple with these 2 elements. You can also use the shortcut syntax: (item1,item2) to create the tuple directly.
untuple
untuple(a_tuple) show elements in the tuple.
The names of the result columns are implementation-specific and subject to change. Do not assume specific column names after untuple.
tuple_element
tuple_element(a_tuple, index, [, default_value]) or tuple_element(a_tuple, name, [, default_value])
A function that allows getting a column from a tuple.
If the second argument is a number index, it is the column index, starting from 1. If the second argument is a string name, it represents the name of the element. Besides, we can provide the third optional argument, such that when index out of bounds or no element exist for the name, the default value returned instead of throwing an exception. The second and third arguments, if provided, must be constants. There is no cost to execute the function.
The function implements operators x.index and x.name.
Other Functions
columns
Not really for arrays, maps, or tuples.
columns(regexp) Dynamic column selection (also known as a COLUMNS expression) allows you to match some columns in a result with a re2 regular expression
apply
Not really for arrays, maps, or tuples.
select <expr> apply( <func> ) Allows you to invoke some function for each row returned by an outer table expression of a query.
For example, select * apply(sum) ..