Merge remote-tracking branch 'origin/main'

Author: MarkusNeusinger

plots/kagi-basic/implementations/pygal.py

@@ -0,0 +1,194 @@
+""" pyplots.ai
+kagi-basic: Basic Kagi Chart
+Library: pygal 3.1.0 | Python 3.13.11
+Quality: 82/100 | Created: 2026-01-08
+"""
+
+import cairosvg
+import numpy as np
+import pygal
+from pygal.style import Style
+
+
+# Data - Generate synthetic stock price data
+np.random.seed(42)
+n_days = 300  # More days for richer Kagi pattern
+returns = np.random.normal(0.0006, 0.02, n_days)
+prices = 100 * np.cumprod(1 + returns)
+
+# Kagi chart calculation with 4% reversal threshold
+reversal_pct = 0.04
+
+# Build Kagi chart columns
+columns = []
+current_direction = "up"
+last_high = prices[0]
+last_low = prices[0]
+prev_swing_high = prices[0]
+prev_swing_low = prices[0]
+col_idx = 0
+
+current_col = {"x": col_idx, "start": prices[0], "end": prices[0], "type": "yang"}
+
+for price in prices[1:]:
+    if current_direction == "up":
+        if price > last_high:
+            last_high = price
+            current_col["end"] = price
+            if price > prev_swing_high:
+                current_col["type"] = "yang"
+        elif price < last_high * (1 - reversal_pct):
+            columns.append(current_col)
+            prev_swing_high = last_high
+            col_idx += 1
+            is_yin = price < prev_swing_low
+            current_col = {
+                "x": col_idx,
+                "start": columns[-1]["end"],
+                "end": price,
+                "type": "yin" if is_yin else columns[-1]["type"],
+            }
+            current_direction = "down"
+            last_low = price
+    else:
+        if price < last_low:
+            last_low = price
+            current_col["end"] = price
+            if price < prev_swing_low:
+                current_col["type"] = "yin"
+        elif price > last_low * (1 + reversal_pct):
+            columns.append(current_col)
+            prev_swing_low = last_low
+            col_idx += 1
+            is_yang = price > prev_swing_high
+            current_col = {
+                "x": col_idx,
+                "start": columns[-1]["end"],
+                "end": price,
+                "type": "yang" if is_yang else columns[-1]["type"],
+            }
+            current_direction = "up"
+            last_high = price
+
+columns.append(current_col)
+
+# Build individual line segments for proper Kagi rendering
+# Each segment is a separate 2-point series to avoid polygon connections
+yang_segments = []  # List of [(x1,y1), (x2,y2)] for yang
+yin_segments = []  # List of [(x1,y1), (x2,y2)] for yin
+
+prev_x = None
+prev_y = None
+
+for col in columns:
+    x = col["x"]
+    y_start = col["start"]
+    y_end = col["end"]
+    seg_type = col["type"]
+
+    # Horizontal connector (shoulder/waist) from previous column
+    if prev_x is not None and prev_x != x:
+        h_segment = [(prev_x, prev_y), (x, prev_y)]
+        if seg_type == "yang":
+            yang_segments.append(h_segment)
+        else:
+            yin_segments.append(h_segment)
+
+    # Vertical line segment
+    v_segment = [(x, y_start), (x, y_end)]
+    if seg_type == "yang":
+        yang_segments.append(v_segment)
+    else:
+        yin_segments.append(v_segment)
+
+    prev_x = x
+    prev_y = y_end
+
+# Colors and stroke widths - large difference for visibility
+YANG_COLOR = "#16A34A"  # Green for bullish
+YIN_COLOR = "#DC2626"  # Red for bearish
+YANG_WIDTH = 18  # Thick for yang
+YIN_WIDTH = 4  # Thin for yin
+
+# Custom style - create colors list with yang color first, yin color second
+custom_style = Style(
+    background="white",
+    plot_background="white",
+    foreground="#333333",
+    foreground_strong="#000000",
+    foreground_subtle="#999999",
+    colors=(YANG_COLOR, YIN_COLOR),
+    title_font_size=64,
+    label_font_size=42,
+    major_label_font_size=38,
+    legend_font_size=38,
+    value_font_size=30,
+    guide_stroke_dasharray="4,4",
+    opacity=1.0,
+    opacity_hover=1.0,
+)
+
+# Create XY chart - disable legend (we'll add manual legend annotation)
+chart = pygal.XY(
+    width=4800,
+    height=2700,
+    style=custom_style,
+    title="kagi-basic · pygal · pyplots.ai",
+    x_title="Kagi Line Index",
+    y_title="Price ($)",
+    show_dots=False,
+    show_x_guides=False,
+    show_y_guides=True,
+    show_legend=False,  # Disable native legend - we'll add custom one
+    stroke=True,
+    fill=False,
+    margin=100,
+)
+
+# Combine all yang segments into one series (for consistent color)
+yang_points = []
+for seg in yang_segments:
+    yang_points.extend(seg)
+    yang_points.append((None, None))  # Break between segments
+
+# Combine all yin segments into one series
+yin_points = []
+for seg in yin_segments:
+    yin_points.extend(seg)
+    yin_points.append((None, None))  # Break between segments
+
+# Add as two series
+chart.add("Yang (Bullish)", yang_points, stroke_style={"width": YANG_WIDTH, "linecap": "round"})
+chart.add("Yin (Bearish)", yin_points, stroke_style={"width": YIN_WIDTH, "linecap": "round"})
+
+# Render to SVG and add custom legend with proper line styles
+svg_data = chart.render()
+svg_str = svg_data.decode("utf-8")
+
+# Add CSS to enforce stroke widths (pygal's stroke_style may not apply correctly)
+css_override = f"""
+.serie-0 .line {{ stroke-width: {YANG_WIDTH}px !important; stroke: {YANG_COLOR} !important; }}
+.serie-1 .line {{ stroke-width: {YIN_WIDTH}px !important; stroke: {YIN_COLOR} !important; }}
+"""
+svg_str = svg_str.replace("</style>", css_override + "</style>")
+
+# Build manual legend that accurately shows thick vs thin lines
+# Position legend in upper right area to avoid axis labels
+legend_svg = f"""
+<g class="manual-legend" transform="translate(3200, 180)">
+  <rect x="-20" y="-30" width="1450" height="80" fill="white" fill-opacity="0.9" rx="8"/>
+  <line x1="0" y1="0" x2="80" y2="0" stroke="{YANG_COLOR}" stroke-width="{YANG_WIDTH}" stroke-linecap="round"/>
+  <text x="100" y="10" font-size="36" fill="#333333" font-family="Verdana, sans-serif">Yang (Bullish) — Thick</text>
+  <line x1="700" y1="0" x2="780" y2="0" stroke="{YIN_COLOR}" stroke-width="{YIN_WIDTH}" stroke-linecap="round"/>
+  <text x="800" y="10" font-size="36" fill="#333333" font-family="Verdana, sans-serif">Yin (Bearish) — Thin</text>
+</g>
+"""
+
+# Insert legend before closing svg tag
+svg_str = svg_str.replace("</svg>", legend_svg + "</svg>")
+
+# Convert to PNG
+cairosvg.svg2png(bytestring=svg_str.encode("utf-8"), write_to="plot.png")
+
+# Save HTML version for interactive view
+chart.render_to_file("plot.html")