implement unknown shape dimension in reshape (#612)

Author: v923z

code/ndarray.c

@@ -2084,24 +2084,51 @@ MP_DEFINE_CONST_FUN_OBJ_1(ndarray_transpose_obj, ndarray_transpose);
 #if NDARRAY_HAS_RESHAPE
 mp_obj_t ndarray_reshape_core(mp_obj_t oin, mp_obj_t _shape, bool inplace) {
     ndarray_obj_t *source = MP_OBJ_TO_PTR(oin);
-    if(!mp_obj_is_type(_shape, &mp_type_tuple)) {
-        mp_raise_TypeError(translate("shape must be a tuple"));
+    if(!mp_obj_is_type(_shape, &mp_type_tuple) && !mp_obj_is_int(_shape)) {
+        mp_raise_TypeError(translate("shape must be integer or tuple of integers"));
+    }
+
+    mp_obj_tuple_t *shape;
+
+    if(mp_obj_is_int(_shape)) {
+        mp_obj_t *items = m_new(mp_obj_t, 1);
+        items[0] = _shape;
+        shape = mp_obj_new_tuple(1, items);
+    } else {
+        shape = MP_OBJ_TO_PTR(_shape);
     }
 
-    mp_obj_tuple_t *shape = MP_OBJ_TO_PTR(_shape);
     if(shape->len > ULAB_MAX_DIMS) {
         mp_raise_ValueError(translate("maximum number of dimensions is " MP_STRINGIFY(ULAB_MAX_DIMS)));
     }
-    size_t *new_shape = m_new0(size_t, ULAB_MAX_DIMS);
 
     size_t new_length = 1;
-    for(uint8_t i=0; i < shape->len; i++) {
-        new_shape[ULAB_MAX_DIMS - i - 1] = mp_obj_get_int(shape->items[shape->len - i - 1]);
-        new_length *= new_shape[ULAB_MAX_DIMS - i - 1];
+    size_t *new_shape = m_new0(size_t, ULAB_MAX_DIMS);
+    uint8_t unknown_dim = 0;
+    uint8_t unknown_index = 0;
+
+    for(uint8_t i = 0; i < shape->len; i++) {
+        int32_t ax_len = mp_obj_get_int(shape->items[shape->len - i - 1]);
+        if(ax_len >= 0) {
+            new_shape[ULAB_MAX_DIMS - i - 1] = (size_t)ax_len;
+            new_length *= new_shape[ULAB_MAX_DIMS - i - 1];
+        } else {
+            unknown_dim++;
+            unknown_index = ULAB_MAX_DIMS - i - 1;
+        }
+    }
+
+    if(unknown_dim > 1) {
+        mp_raise_ValueError(translate("can only specify one unknown dimension"));
+    } else if(unknown_dim == 1) {
+        new_shape[unknown_index] = source->len / new_length;
+        new_length = source->len;
     }
+
     if(source->len != new_length) {
-        mp_raise_ValueError(translate("input and output shapes are not compatible"));
+        mp_raise_ValueError(translate("cannot reshape array"));
     }
+
     ndarray_obj_t *ndarray;
     if(ndarray_is_dense(source)) {
         int32_t *new_strides = strides_from_shape(new_shape, source->dtype);
@@ -2118,7 +2145,11 @@ mp_obj_t ndarray_reshape_core(mp_obj_t oin, mp_obj_t _shape, bool inplace) {
         if(inplace) {
             mp_raise_ValueError(translate("cannot assign new shape"));
         }
-        ndarray = ndarray_new_ndarray_from_tuple(shape, source->dtype);
+        if(mp_obj_is_type(_shape, &mp_type_tuple)) {
+            ndarray = ndarray_new_ndarray_from_tuple(shape, source->dtype);
+        } else {
+            ndarray = ndarray_new_linear_array(source->len, source->dtype);
+        }
         ndarray_copy_array(source, ndarray, 0);
     }
     return MP_OBJ_FROM_PTR(ndarray);

code/ulab.c

@@ -33,7 +33,7 @@
 #include "user/user.h"
 #include "utils/utils.h"
 
-#define ULAB_VERSION 6.0.10
+#define ULAB_VERSION 6.0.11
 #define xstr(s) str(s)
 #define str(s) #s
 

docs/ulab-change-log.md

@@ -1,5 +1,11 @@
 Sat, 6 May 2023
 
+version 6.0.11
+
+    .reshape can now interpret unknown shape dimension
+
+Sat, 6 May 2023
+
 version 6.0.10
 
     fix binary division