Work in progress

spacy/visualization.py

@@ -1,5 +1,41 @@
 from spacy.tokens import Doc, Token
+from spacy.util import working_dir
 
+HORIZONTAL_LINE_PART_AWAY_FROM_ROOT = 1
+HORIZONTAL_LINE_PART_TOWARDS_ROOT = 2
+UPPER_VERTICAL_LINE_PART = 4
+LOWER_VERTICAL_LINE_PART = 8
+ARROWHEAD = 16
+
+SPACE = 0
+HORIZONTAL_LINE = 3
+VERTICAL_LINE = 12
+
+ROOT_RIGHT_CHARS = {
+    0: " ",
+    3: "═",
+    5: "╝",
+    7: "╩",
+    9: "╗",
+    11: "╦",
+    12: "║",
+    13: "╣",
+    15: "╬",
+    16: "<",
+}
+
+ROOT_LEFT_CHARS = {
+    0: " ",
+    3: "═",
+    5: "╚",
+    7: "╩",
+    9: "╔",
+    11: "╦",
+    12: "║",
+    13: "╠",
+    15: "╬",
+    16: ">",
+}
 
 class Visualizer:
     @staticmethod
@@ -12,17 +48,17 @@ class Visualizer:
         Adapted from https://github.com/KoichiYasuoka/deplacy
         """
         heads = [
-            -1
+            None
             if token.dep_.lower() == "root" or token.head.i == token.i
             else token.head.i
             for token in doc
         ]
         children_lists = [[] for _ in range(len(doc))]
         for child, head in enumerate(heads):
-            if head != -1:
+            if head is not None:
                 children_lists[head].append(child)
         all_indices_ordered_by_column = []
-        indices_in_current_column = [i for i, h in enumerate(heads) if h == -1]
+        indices_in_current_column = [i for i, h in enumerate(heads) if h is None]
         while len(indices_in_current_column) > 0:
             all_indices_ordered_by_column = (
                 indices_in_current_column + all_indices_ordered_by_column
@@ -36,7 +72,7 @@ class Visualizer:
         # -1: root token with no arrow; 0: length not yet set
         horizontal_line_lengths = [
             -1
-            if heads[i] == -1
+            if heads[i] is None
             else 1
             if len(children_lists[i]) == 0 and abs(heads[i] - i) == 1
             else 0
@@ -97,9 +133,83 @@ class Visualizer:
                 ] = working_horizontal_line_length
         print(horizontal_line_lengths)
 
+        max_horizontal_line_length = max(horizontal_line_lengths)
+        char_matrix = [
+            [SPACE] * max_horizontal_line_length * 2 for _ in range(len(doc))
+        ]
+        for working_token_index in range(len(doc)):
+            head_token_index = heads[working_token_index]
+            if head_token_index is None:
+                continue
+            first_index_in_relation = min(working_token_index, head_token_index)
+            second_index_in_relation = max(working_token_index, head_token_index)
+            char_horizontal_line_length = (
+                2 * horizontal_line_lengths[working_token_index]
+            )
+
+            char_matrix[first_index_in_relation][char_horizontal_line_length - 1] |= (
+                HORIZONTAL_LINE_PART_AWAY_FROM_ROOT + LOWER_VERTICAL_LINE_PART
+            )
+            char_matrix[second_index_in_relation][char_horizontal_line_length - 1] |= (
+                HORIZONTAL_LINE_PART_TOWARDS_ROOT + UPPER_VERTICAL_LINE_PART
+            )
+            for working_horizontal_position in range(char_horizontal_line_length - 1):
+                if (
+                    char_matrix[working_token_index][working_horizontal_position]
+                    != VERTICAL_LINE
+                ):
+                    char_matrix[working_token_index][
+                        working_horizontal_position
+                    ] |= HORIZONTAL_LINE
+            for working_vertical_position in range(
+                first_index_in_relation + 1, second_index_in_relation
+            ):
+                if (
+                    char_matrix[working_vertical_position][
+                        char_horizontal_line_length - 1
+                    ]
+                    != HORIZONTAL_LINE
+                ):
+                    char_matrix[working_vertical_position][
+                        char_horizontal_line_length - 1
+                    ] |= VERTICAL_LINE
+        for working_token_index in (i for i in range(len(doc)) if heads[i] is not None):
+            for working_horizontal_position in range(
+                2 * horizontal_line_lengths[working_token_index], -1, -1
+            ):
+                print(working_token_index, working_horizontal_position)
+                if (
+                    working_horizontal_position > 0
+                    and char_matrix[working_token_index][working_horizontal_position]
+                    == VERTICAL_LINE
+                    and char_matrix[
+                        working_token_index][working_horizontal_position - 1
+                    ]
+                    == 0
+                ):
+                    # jump over crossing line in non-projective parse case
+                    continue
+                if (
+                    char_matrix[working_token_index][working_horizontal_position]
+                    != SPACE
+                ):
+                    char_matrix[working_token_index][
+                        working_horizontal_position + 1
+                    ] = ARROWHEAD
+                    break
+                if working_horizontal_position == 0:
+                    char_matrix[working_token_index][
+                        working_horizontal_position
+                    ] = ARROWHEAD
+                else:
+                    char_matrix[working_token_index][
+                        working_horizontal_position
+                    ] |= HORIZONTAL_LINE
+        return [''.join(ROOT_RIGHT_CHARS[char_matrix[vertical_position][horizontal_position]] for horizontal_position in range((max_horizontal_line_length * 2 - 1))) for vertical_position in range(len(doc))]
 
 import spacy
 
 nlp = spacy.load("en_core_web_sm")
 doc = nlp("I saw a horse yesterday that was injured")
-Visualizer().render_dependency_trees(doc)
+
+print (Visualizer().render_dependency_trees(doc))