From 13ba9d0f5304c96f5e685bbd5201df732ca80b15 Mon Sep 17 00:00:00 2001
From: Dmitry <dmitry.petrov@nevesomo.com>
Date: Mon, 4 Sep 2017 13:36:51 -0700
Subject: [PATCH] Show target metric deltas

---
 dvc/graph/commit.py   | 12 +++++++++++-
 dvc/graph/workflow.py | 36 ++++++++++++++++++++++++++++++++++--
 2 files changed, 45 insertions(+), 3 deletions(-)

diff --git a/dvc/graph/commit.py b/dvc/graph/commit.py
index 8dacfae38..6cce7dd03 100644
--- a/dvc/graph/commit.py
+++ b/dvc/graph/commit.py
@@ -14,6 +14,7 @@ class Commit(object):
         self._comment = comment
         self._is_target = is_target
         self._target_metric = target_metric
+        self._target_metric_delta = None
         self._branch_tips = [] if branch_tips is None else branch_tips
 
         self._is_collapsed = False
@@ -41,11 +42,13 @@ class Commit(object):
         metric_text = ''
         if self._is_target and self._target_metric:
             metric_text = '\nTarget metric: {}'.format(self._target_metric)
+            if self._target_metric_delta is not None:
+                metric_text += ' ({:+f})'.format(self._target_metric_delta)
 
         if self._is_collapsed:
             return branch_text + self.COLLAPSED_TEXT + metric_text
 
-        return branch_text + self._comment[:self.TEXT_LIMIT] + '\n' + self.hash + metric_text
+        return branch_text + self._comment[:self.TEXT_LIMIT] + metric_text + '\n' + self.hash
 
     @property
     def is_repro(self):
@@ -73,3 +76,10 @@ class Commit(object):
     def add_branch_tips(self, tips):
         for tip in tips:
             self._branch_tips.append(tip)
+
+    def set_target_metric_delta(self, value):
+        self._target_metric_delta = value
+
+    @property
+    def target_metric_delta(self):
+        return self._target_metric_delta
diff --git a/dvc/graph/workflow.py b/dvc/graph/workflow.py
index e6870b48c..4c72fdd67 100644
--- a/dvc/graph/workflow.py
+++ b/dvc/graph/workflow.py
@@ -1,6 +1,7 @@
 import networkx as nx
 
 from dvc.exceptions import DvcException
+from dvc.logger import Logger
 
 
 class WorkflowError(DvcException):
@@ -9,13 +10,13 @@ class WorkflowError(DvcException):
 
 
 class Workflow(object):
-    def __init__(self, target, merges_map, branches_map=None, root='', no_repro_commits=True):
+    def __init__(self, target, merges_map, branches_map=None, no_repro_commits=True):
         self._target = target
         self._merges_map = merges_map
         self._branches_map = branches_map
 
         self._commits = {}
-        self._root = root
+        self._root_hash = None
 
         self._edges = {}
         self._back_edges = {}
@@ -35,11 +36,16 @@ class Workflow(object):
             self._back_edges[commit.hash] = set()
         for p in commit.parent_hashes:
             self._back_edges[commit.hash].add(p)
+
+        if not commit.parent_hashes:
+            self._root_hash = commit.hash
         pass
 
     def build_graph(self):
         g = nx.DiGraph(name='DVC Workflow', directed=False)
 
+        self.derive_target_metric_deltas()
+
         if self._no_repro_commits:
             self.collapse_repro_commits()
 
@@ -120,3 +126,29 @@ class Workflow(object):
         for h in commit_hashes:
             edges[h].remove(hash)
             edges[h] |= child_commit_hashes
+
+    def derive_target_metric_deltas(self):
+        if not self._target:
+            return
+
+        if self._root_hash not in self._commits:
+            Logger.warn('Root commit cannot be found')
+
+        current_target_metric = None
+        commit = self._commits[self._root_hash]
+        self._traverse_target_metric(commit, current_target_metric)
+        pass
+
+    def _traverse_target_metric(self, commit, current_target_metric):
+        new_target_metric = current_target_metric
+        if commit.target_metric is not None:
+            new_target_metric = commit.target_metric
+            if current_target_metric is None:
+                commit.set_target_metric_delta(0.0)
+            else:
+                commit.set_target_metric_delta(new_target_metric - current_target_metric)
+
+        if commit.hash in self._edges:
+            for hash in self._edges[commit.hash]:
+                self._traverse_target_metric(self._commits[hash], new_target_metric)
+        pass