Cumsum cumprod (#492)

* Add cumsum and cumprod procedures"

* Add cumsum and cumprod procedures

* Adding cumsum and cumprod testes

* Add mixin

* create another test block for cumsum

* Import the broadcasting operators

Co-authored-by: Mamy Ratsimbazafy <mamy_github@numforge.co>

src/arraymancer/tensor/aggregate.nim

@@ -15,6 +15,7 @@
 import  ./data_structure,
         ./init_cpu,
         ./higher_order_foldreduce,
+        ./operators_broadcasted,
         ./math_functions,
         ./accessors,
         ./algorithms,
@@ -245,3 +246,35 @@ proc iqr*[T](t: Tensor[T]): float =
   let tS = t.sorted
   result = percentile(tS, 75, isSorted = true) -
            percentile(tS, 25, isSorted = true)
+
+proc cumsum*[T](t: Tensor[T], axis:int): Tensor[T] = # from hugogranstrom
+  ## Calculates the cumulative sum of a rank-n Tensor.
+  ## Inputs:
+  ##  - t: a rank-n tensor to cumulatively sum
+  ##  - axis: int
+  ## Returns:
+  ##  - A tensor cumulatively summed at axis, that is, add each value to
+  mixin `_`
+  result = zeros_like(t)
+  for i, tAxis in enumerateAxis(t, axis):
+    var temp = result.atAxisIndex(axis, i)
+    if i == 0:
+      temp[_] = tAxis
+    else:
+      temp[_] = result.atAxisIndex(axis, i-1) + tAxis
+
+proc cumprod*[T](t: Tensor[T], axis:int): Tensor[T] = # from hugogranstrom
+  ## Calculates the cumulative sum of a rank-n Tensor.
+  ## Inputs:
+  ##  - t: a rank-n tensor to cumulatively sum
+  ##  - axis: int
+  ## Returns:
+  ##  - A tensor cumulatively summed at axis, that is, add each value to
+  mixin `_`
+  result = zeros_like(t)
+  for i, tAxis in enumerateAxis(t, axis):
+    var temp = result.atAxisIndex(axis, i)
+    if i == 0:
+      temp[_] = tAxis
+    else:
+      temp[_] = result.atAxisIndex(axis, i-1) *. tAxis

tests/tensor/test_aggregate.nim

@@ -164,5 +164,31 @@ proc main() =
         [[3], [3], [3]], [[3], [3], [3]]
       ].toTensor
 
+      test "cumsum":
+        let a = [[0, 4, 7],
+                 [1, 9, 5],
+                 [3, 4, 1]].toTensor
+
+        check: cumsum(a, 0) == [[0, 4,  7],
+                                [1, 13, 12],
+                                [4, 17, 13]].toTensor
+
+        check: cumsum(a, 1) == [[0, 4, 11],
+                                [1, 10, 15],
+                                [3, 7, 8]].toTensor
+      test "cumprod":
+        let a = [[0, 4, 7],
+                 [1, 9, 5],
+                 [3, 4, 1]].toTensor
+
+        check: cumprod(a, 0) == [[0, 4,   7],
+                                 [0, 36,  35],
+                                 [0, 144, 35]].toTensor
+
+        check: cumprod(a, 1) == [[0, 0, 0],
+                                 [1, 9, 45],
+                                 [3, 12, 12]].toTensor
+
+
 main()
 GC_fullCollect()