update(gantt-dependencies): seaborn — Fix dependency arrows to connect end→start and ensure correct temporal scheduling

Author: MarkusNeusinger

plots/gantt-dependencies/implementations/seaborn.py

@@ -1,7 +1,7 @@
-""" pyplots.ai
+"""pyplots.ai
 gantt-dependencies: Gantt Chart with Dependencies
-Library: seaborn 0.13.2 | Python 3.13.11
-Quality: 91/100 | Created: 2026-01-15
+Library: seaborn 0.13.2 | Python 3.14
+Quality: /100 | Updated: 2026-02-25
 """
 
 import matplotlib.patches as mpatches
@@ -16,6 +16,7 @@
 sns.set_theme(style="whitegrid")
 
 # Data: Software Development Project with Dependencies
+# All dependent tasks start at or after their predecessors end
 tasks_data = [
     # Requirements Phase
     {
@@ -49,51 +50,51 @@
     },
     {
         "task": "Database Design",
-        "start": "2024-02-01",
-        "end": "2024-02-12",
+        "start": "2024-02-09",
+        "end": "2024-02-20",
         "group": "Design",
         "depends_on": ["System Architecture"],
     },
     {
         "task": "UI/UX Design",
-        "start": "2024-02-05",
-        "end": "2024-02-18",
+        "start": "2024-02-09",
+        "end": "2024-02-22",
         "group": "Design",
         "depends_on": ["System Architecture"],
     },
     {
         "task": "Design Review",
-        "start": "2024-02-19",
-        "end": "2024-02-23",
+        "start": "2024-02-23",
+        "end": "2024-02-28",
         "group": "Design",
         "depends_on": ["Database Design", "UI/UX Design"],
     },
     # Development Phase
     {
         "task": "Backend Core",
-        "start": "2024-02-26",
+        "start": "2024-02-29",
         "end": "2024-03-18",
         "group": "Development",
         "depends_on": ["Design Review"],
     },
     {
         "task": "API Development",
-        "start": "2024-03-04",
-        "end": "2024-03-22",
+        "start": "2024-03-19",
+        "end": "2024-04-05",
         "group": "Development",
         "depends_on": ["Backend Core"],
     },
     {
         "task": "Frontend Components",
-        "start": "2024-03-11",
-        "end": "2024-03-29",
+        "start": "2024-04-06",
+        "end": "2024-04-22",
         "group": "Development",
         "depends_on": ["UI/UX Design", "API Development"],
     },
     {
         "task": "Integration",
-        "start": "2024-04-01",
-        "end": "2024-04-12",
+        "start": "2024-04-23",
+        "end": "2024-05-06",
         "group": "Development",
         "depends_on": ["API Development", "Frontend Components"],
     },
@@ -107,19 +108,19 @@
     },
     {
         "task": "Integration Testing",
-        "start": "2024-04-08",
-        "end": "2024-04-19",
+        "start": "2024-05-07",
+        "end": "2024-05-17",
         "group": "Testing",
         "depends_on": ["Integration", "Unit Testing"],
     },
     {
         "task": "UAT",
-        "start": "2024-04-22",
-        "end": "2024-05-03",
+        "start": "2024-05-20",
+        "end": "2024-05-31",
         "group": "Testing",
         "depends_on": ["Integration Testing"],
     },
-    {"task": "Bug Fixes", "start": "2024-05-06", "end": "2024-05-17", "group": "Testing", "depends_on": ["UAT"]},
+    {"task": "Bug Fixes", "start": "2024-06-03", "end": "2024-06-14", "group": "Testing", "depends_on": ["UAT"]},
 ]
 
 df = pd.DataFrame(tasks_data)
@@ -155,10 +156,8 @@
 fig, ax = plt.subplots(figsize=(16, 9))
 
 # Create data for seaborn lineplot (bars as thick lines)
-# This uses seaborn's lineplot to draw horizontal bars as line segments
 line_data = []
 for _, row in df.iterrows():
-    # Create start and end points for each task bar
     line_data.append(
         {"x": row["start_num"], "y": row["y_pos"], "task": row["task"], "group": row["group"], "point": "start"}
     )
@@ -193,7 +192,7 @@
 
     ax.plot([group_start, group_end], [y, y], color=color, linewidth=10, alpha=0.4, solid_capstyle="round")
 
-# Draw dependency arrows
+# Draw dependency arrows from right edge of predecessor to left edge of successor
 for _, row in df.iterrows():
     if row["depends_on"]:
         end_y = task_to_y[row["task"]]
@@ -230,9 +229,15 @@
         all_y.append(task_to_y[task])
 
 ax.set_yticks(all_y)
-ax.set_yticklabels(all_labels, fontsize=12)
+ax.set_yticklabels(all_labels, fontsize=13)
 ax.invert_yaxis()
 
+# Bold group labels for hierarchy emphasis
+for label in ax.get_yticklabels():
+    if label.get_text().startswith("▪"):
+        label.set_fontweight("bold")
+        label.set_fontsize(14)
+
 # X-axis formatting (dates)
 max_day = int(df["end_num"].max()) + 7
 date_ticks = np.arange(0, max_day, 14)

plots/gantt-dependencies/metadata/seaborn.yaml

@@ -1,16 +1,16 @@
 library: seaborn
 specification_id: gantt-dependencies
 created: '2026-01-15T21:03:35Z'
-updated: '2026-01-15T21:06:24Z'
-generated_by: claude-opus-4-5-20251101
+updated: '2026-02-25T14:40:00Z'
+generated_by: claude-opus-4-6
 workflow_run: 21046151686
 issue: 3830
-python_version: 3.13.11
+python_version: '3.14'
 library_version: 0.13.2
 preview_url: https://storage.googleapis.com/pyplots-images/plots/gantt-dependencies/seaborn/plot.png
 preview_thumb: https://storage.googleapis.com/pyplots-images/plots/gantt-dependencies/seaborn/plot_thumb.png
 preview_html: null
-quality_score: 91
+quality_score: null
 review:
   strengths:
   - Excellent hierarchical organization with group headers and indented task names

plots/gantt-dependencies/specification.md

@@ -23,10 +23,11 @@ A Gantt chart that visualizes project schedules with task dependencies and group
 
 ## Notes
 
-- Draw dependency arrows/connectors from the end of predecessor tasks to the start of successor tasks
+- Draw dependency arrows from the right edge (end date) of each predecessor bar to the left edge (start date) of the successor bar
 - Use different visual styles for dependency types (finish-to-start is most common)
 - Group headers should show aggregate timeline spanning from earliest to latest task in the group
 - Consider indentation or color coding to distinguish groups from individual tasks
 - Arrows should avoid overlapping task bars where possible
 - Include a legend explaining dependency line styles if multiple types are used
+- Dependent tasks must be scheduled to start at or after the end of their predecessor — never before
 - Vertical alignment should clearly show task hierarchy (groups above their child tasks)

plots/gantt-dependencies/specification.yaml

@@ -6,7 +6,7 @@ title: Gantt Chart with Dependencies
 
 # Specification tracking
 created: 2026-01-15T20:43:22Z
-updated: 2026-01-15T20:43:22Z
+updated: 2026-02-25T12:00:00Z
 issue: 3830
 suggested: Eifi1
 
@@ -27,3 +27,5 @@ tags:
     - grouped
     - hierarchical
     - annotated
+    - temporal
+    - dependencies