Split a map using Groovy - grails

Question

I want to split up a map into an array of maps. For example, if there is a map with 25 key/value pairs. I want an array of maps with no more than 10 elements in each map.
How would I do this in groovy?
I have a solution which I am not excited about, is there better groovy version:
static def splitMap(m, count){
if (!m) return
def keys = m.keySet().toList()
def result = []
def num = Math.ceil(m?.size() / count)
(1..num).each {
def min = (it - 1) * count
def max = it * count > keys.size() ? keys.size() - 1 : it * count - 1
result[it - 1] = [:]
keys[min..max].each {k ->
result[it - 1][k] = m[k]
}
}
result
}
m is the map. Count is the max number of elements within the map.

Answer 1

Adapting my answer to this question on partitioning a List, I came up with this method:
Map.metaClass.partition = { size ->
def rslt = delegate.inject( [ [:] ] ) { ret, elem ->
( ret.last() << elem ).size() >= size ? ret << [:] : ret
}
rslt.last() ? rslt : rslt[ 0..-2 ]
}
So if you take this map:
def origMap = [1:'a', 2:'b', 3:'c', 4:'d', 5:'e', 6:'f']
All of the following assertions pass :-)
assert [ [1:'a'], [2:'b'], [3:'c'], [4:'d'], [5:'e'], [6:'f'] ] == origMap.partition( 1 )
assert [ [1:'a', 2:'b'], [3:'c', 4:'d'], [5:'e', 6:'f'] ] == origMap.partition( 2 )
assert [ [1:'a', 2:'b', 3:'c'], [4:'d', 5:'e', 6:'f'] ] == origMap.partition( 3 )
assert [ [1:'a', 2:'b', 3:'c', 4:'d'], [5:'e', 6:'f'] ] == origMap.partition( 4 )
assert [ [1:'a', 2:'b', 3:'c', 4:'d', 5:'e'], [6:'f'] ] == origMap.partition( 5 )
assert [ [1:'a', 2:'b', 3:'c', 4:'d', 5:'e', 6:'f'] ] == origMap.partition( 6 )
Or, as a Category (to avoid having to add anything to the metaClass of Map:
class MapPartition {
static List partition( Map delegate, int size ) {
def rslt = delegate.inject( [ [:] ] ) { ret, elem ->
( ret.last() << elem ).size() >= size ? ret << [:] : ret
}
rslt.last() ? rslt : rslt[ 0..-2 ]
}
}
Then, where you need this functionality, you can simply use the Category like so:
use( MapPartition ) {
assert [ [1:'a'], [2:'b'], [3:'c'], [4:'d'], [5:'e'], [6:'f'] ] == origMap.partition( 1 )
assert [ [1:'a', 2:'b'], [3:'c', 4:'d'], [5:'e', 6:'f'] ] == origMap.partition( 2 )
assert [ [1:'a', 2:'b', 3:'c'], [4:'d', 5:'e', 6:'f'] ] == origMap.partition( 3 )
assert [ [1:'a', 2:'b', 3:'c', 4:'d'], [5:'e', 6:'f'] ] == origMap.partition( 4 )
assert [ [1:'a', 2:'b', 3:'c', 4:'d', 5:'e'], [6:'f'] ] == origMap.partition( 5 )
assert [ [1:'a', 2:'b', 3:'c', 4:'d', 5:'e', 6:'f'] ] == origMap.partition( 6 )
}