feat(letsplot): implement line-stress-strain

plots/line-stress-strain/implementations/python/letsplot.py

@@ -1,240 +1,234 @@
-""" pyplots.ai
+"""anyplot.ai
 line-stress-strain: Engineering Stress-Strain Curve
-Library: letsplot 4.9.0 | Python 3.14.3
-Quality: 92/100 | Created: 2026-03-20
+Library: letsplot 4.10.1 | Python 3.13.14
+Quality: 86/100 | Updated: 2026-06-21
 """
 
+import os
+
 import numpy as np
 import pandas as pd
 from lets_plot import *  # noqa: F403
-from lets_plot.export import ggsave as export_ggsave
+from lets_plot.export import ggsave
 
 
 LetsPlot.setup_html()  # noqa: F405
 
-# Data - Mild steel tensile test simulation
+THEME = os.getenv("ANYPLOT_THEME", "light")
+PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
+ELEVATED_BG = "#FFFDF6" if THEME == "light" else "#242420"
+INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
+INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
+INK_MUTED = "#6B6A63" if THEME == "light" else "#A8A79F"
+
+# Imprint palette positions
+BRAND = "#009E73"  # green — main stress-strain curve (first series)
+COLOR_OFFSET = "#C475FD"  # lavender — 0.2% offset line
+COLOR_YIELD = "#4467A3"  # blue — yield point
+COLOR_UTS = "#AE3030"  # matte red — UTS (semantic: peak stress / failure onset)
+COLOR_FRACTURE = "#BD8233"  # ochre — fracture point
+
+# Theme-adaptive region background tints derived from Imprint palette
+if THEME == "light":
+    region_fill = {"Elastic": "#D6EEE6", "Strain Hardening": "#D6DDF0", "Necking": "#F0D6D6"}
+else:
+    region_fill = {"Elastic": "#172920", "Strain Hardening": "#171C2C", "Necking": "#2C1717"}
+
+# Data — Mild steel tensile test simulation
 np.random.seed(42)
-
-# Material properties for mild steel
 youngs_modulus = 210000  # MPa
 yield_strength = 250  # MPa
 uts = 400  # MPa (ultimate tensile strength)
 fracture_strain = 0.35
 uts_strain = 0.22
-yield_strain = yield_strength / youngs_modulus  # ~0.00119
+yield_strain = yield_strength / youngs_modulus
 
 # Elastic region (0 to yield)
-n_elastic = 60
-strain_elastic = np.linspace(0, yield_strain, n_elastic)
+strain_elastic = np.linspace(0, yield_strain, 60)
 stress_elastic = youngs_modulus * strain_elastic
 
-# Yield plateau (mild steel has a distinct yield point)
-n_plateau = 20
-strain_plateau = np.linspace(yield_strain, 0.015, n_plateau)
-stress_plateau = yield_strength + np.random.normal(0, 1.5, n_plateau)
+# Yield plateau (mild steel distinct yield point)
+strain_plateau = np.linspace(yield_strain, 0.015, 20)
+stress_plateau = yield_strength + np.random.normal(0, 1.5, 20)
 
-# Strain hardening region (from end of plateau to UTS)
-n_hardening = 120
-strain_hardening = np.linspace(0.015, uts_strain, n_hardening)
+# Strain hardening
+strain_hardening = np.linspace(0.015, uts_strain, 120)
 stress_hardening = yield_strength + (uts - yield_strength) * (
     1 - np.exp(-8 * (strain_hardening - 0.015) / (uts_strain - 0.015))
 )
-stress_hardening += np.random.normal(0, 1.0, n_hardening)
+stress_hardening += np.random.normal(0, 1.0, 120)
 
-# Necking region (UTS to fracture)
-n_necking = 60
-strain_necking = np.linspace(uts_strain, fracture_strain, n_necking)
+# Necking (UTS to fracture)
+strain_necking = np.linspace(uts_strain, fracture_strain, 60)
 stress_necking = uts - (uts - 280) * ((strain_necking - uts_strain) / (fracture_strain - uts_strain)) ** 1.5
-stress_necking += np.random.normal(0, 1.5, n_necking)
+stress_necking += np.random.normal(0, 1.5, 60)
 
-# Combine all regions
 strain = np.concatenate([strain_elastic, strain_plateau, strain_hardening, strain_necking])
 stress = np.concatenate([stress_elastic, stress_plateau, stress_hardening, stress_necking])
-
 df = pd.DataFrame({"strain": strain, "stress": stress})
 
 # 0.2% offset line for yield point determination
 offset_val = 0.002
-offset_line_strain = np.linspace(offset_val, offset_val + yield_strength / youngs_modulus + 0.003, 50)
-offset_line_stress = youngs_modulus * (offset_line_strain - offset_val)
-offset_line_stress = np.clip(offset_line_stress, 0, yield_strength + 30)
-df_offset = pd.DataFrame({"strain": offset_line_strain, "stress": offset_line_stress})
+offset_strain = np.linspace(offset_val, offset_val + yield_strength / youngs_modulus + 0.003, 50)
+offset_stress = np.clip(youngs_modulus * (offset_strain - offset_val), 0, yield_strength + 30)
+df_offset = pd.DataFrame({"strain": offset_strain, "stress": offset_stress})
 
 # Key points
 yield_point_strain = offset_val + yield_strength / youngs_modulus
-yield_point_stress = yield_strength
 fracture_stress = stress_necking[-1]
-
 df_points = pd.DataFrame(
     {
         "strain": [yield_point_strain, uts_strain, fracture_strain],
-        "stress": [yield_point_stress, uts, fracture_stress],
-        "label": [f"Yield Point ({yield_strength} MPa)", f"UTS ({uts} MPa)", f"Fracture ({fracture_stress:.0f} MPa)"],
+        "stress": [yield_strength, uts, fracture_stress],
         "type": ["Yield", "UTS", "Fracture"],
     }
 )
 
-# Consolidated annotations DataFrame
+# Annotation labels
 df_annotations = pd.DataFrame(
     {
-        "x": [yield_point_strain + 0.012, uts_strain + 0.015, fracture_strain - 0.045, 0.008, 0.007, 0.005, 0.11, 0.29],
-        "y": [yield_point_stress + 15, uts + 10, fracture_stress - 30, 130, 60, 350, 350, 350],
+        "x": [
+            yield_point_strain + 0.025,
+            uts_strain + 0.015,
+            fracture_strain - 0.045,
+            0.002,
+            0.007,
+            0.0075,
+            0.11,
+            0.29,
+        ],
+        "y": [yield_strength + 15, uts + 10, fracture_stress - 30, 180, 60, 375, 350, 310],
         "label": [
             f"Yield Point\n({yield_strength} MPa)",
             f"UTS ({uts} MPa)",
             "Fracture",
             f"E = {youngs_modulus // 1000} GPa",
             "0.2% offset",
             "Elastic",
-            "Strain Hardening",
+            "Strain\nHardening",
             "Necking",
         ],
         "group": ["yield", "uts", "fracture", "modulus", "offset", "region", "region", "region"],
     }
 )
 
-# Colorblind-safe palette: blue, purple, gray (avoids orange/green pair)
-color_yield = "#9467BD"  # purple
-color_uts = "#D62728"  # red
-color_fracture = "#7F7F7F"  # gray
-color_main = "#306998"  # Python blue
-color_offset = "#E377C2"  # pink
-
-# Segment connector lines from key points to annotations (distinctive lets-plot feature)
+# Connector lines from key points to annotation labels
 df_segments = pd.DataFrame(
     {
         "x": [yield_point_strain, uts_strain, fracture_strain],
-        "y": [yield_point_stress, uts, fracture_stress],
-        "xend": [yield_point_strain + 0.011, uts_strain + 0.014, fracture_strain - 0.035],
-        "yend": [yield_point_stress + 12, uts + 8, fracture_stress - 22],
+        "y": [yield_strength, uts, fracture_stress],
+        "xend": [yield_point_strain + 0.023, uts_strain + 0.014, fracture_strain - 0.035],
+        "yend": [yield_strength + 12, uts + 8, fracture_stress - 22],
     }
 )
 
+# Region background rectangles
+df_regions = pd.DataFrame(
+    {
+        "xmin": [0, 0.015, uts_strain],
+        "xmax": [0.015, uts_strain, fracture_strain],
+        "ymin": [0, 0, 0],
+        "ymax": [450, 450, 450],
+        "region": ["Elastic", "Strain Hardening", "Necking"],
+    }
+)
+
+# Combined fill color mapping (regions + key points share the fill aesthetic)
+fill_colors = {**region_fill, "Yield": COLOR_YIELD, "UTS": COLOR_UTS, "Fracture": COLOR_FRACTURE}
+
+title = "line-stress-strain · python · letsplot · anyplot.ai"
+
 # Plot
 plot = (
     ggplot()
-    # Region background bands using geom_rect (distinctive lets-plot feature)
-    + geom_rect(
-        aes(xmin="xmin", xmax="xmax", ymin="ymin", ymax="ymax", fill="region"),
-        data=pd.DataFrame(
-            {
-                "xmin": [0, 0.015, uts_strain],
-                "xmax": [0.015, uts_strain, fracture_strain],
-                "ymin": [0, 0, 0],
-                "ymax": [460, 460, 460],
-                "region": ["Elastic", "Strain Hardening", "Necking"],
-            }
-        ),
-        alpha=0.35,
-    )
-    + scale_fill_manual(
-        values={
-            "Elastic": "#DAE8FC",
-            "Strain Hardening": "#FFF2CC",
-            "Necking": "#F8D7DA",
-            "Yield": color_yield,
-            "UTS": color_uts,
-            "Fracture": color_fracture,
-        }
-    )
-    # Main stress-strain curve with tooltips (distinctive lets-plot feature)
+    + geom_rect(aes(xmin="xmin", xmax="xmax", ymin="ymin", ymax="ymax", fill="region"), data=df_regions, alpha=0.2)
     + geom_line(
         aes(x="strain", y="stress"),
         data=df,
-        color=color_main,
-        size=2.0,
+        color=BRAND,
+        size=1.5,
         tooltips=layer_tooltips()
         .format("strain", ".4f")
         .format("stress", ".1f")
         .line("Strain: @strain")
         .line("Stress: @stress MPa"),
     )
-    # 0.2% offset line
-    + geom_line(aes(x="strain", y="stress"), data=df_offset, color=color_offset, size=1.2, linetype="dashed")
-    # Segment connectors from points to labels (geom_segment - distinctive feature)
+    + geom_line(aes(x="strain", y="stress"), data=df_offset, color=COLOR_OFFSET, size=1.0, linetype="dashed")
     + geom_segment(
-        aes(x="x", y="y", xend="xend", yend="yend"), data=df_segments, color="#999999", size=0.6, linetype="dotted"
+        aes(x="x", y="y", xend="xend", yend="yend"), data=df_segments, color=INK_SOFT, size=0.5, linetype="dotted"
     )
-    # Key points with tooltips (distinctive lets-plot feature)
     + geom_point(
         aes(x="strain", y="stress", fill="type"),
         data=df_points,
-        color="white",
-        size=7,
+        color=PAGE_BG,
+        size=5,
         shape=21,
-        stroke=1.2,
+        stroke=1.5,
         tooltips=layer_tooltips().line("@type").line("Strain: @strain").line("Stress: @stress MPa"),
     )
+    + scale_fill_manual(values=fill_colors)
     + guides(fill="none")
-    # Annotations - key points
     + geom_text(
         aes(x="x", y="y", label="label"),
         data=df_annotations.query("group == 'yield'"),
-        size=11,
-        color=color_yield,
+        size=4,
+        color=COLOR_YIELD,
         hjust=0,
     )
     + geom_text(
-        aes(x="x", y="y", label="label"), data=df_annotations.query("group == 'uts'"), size=11, color=color_uts, hjust=0
+        aes(x="x", y="y", label="label"), data=df_annotations.query("group == 'uts'"), size=4, color=COLOR_UTS, hjust=0
     )
     + geom_text(
         aes(x="x", y="y", label="label"),
         data=df_annotations.query("group == 'fracture'"),
-        size=11,
-        color=color_fracture,
+        size=4,
+        color=COLOR_FRACTURE,
         hjust=0.5,
     )
-    # Elastic modulus annotation
     + geom_text(
         aes(x="x", y="y", label="label"),
         data=df_annotations.query("group == 'modulus'"),
-        size=10,
-        color=color_main,
+        size=3.5,
+        color=BRAND,
         hjust=0,
         fontface="italic",
     )
-    # Offset label
     + geom_text(
         aes(x="x", y="y", label="label"),
         data=df_annotations.query("group == 'offset'"),
-        size=9,
-        color=color_offset,
+        size=3.5,
+        color=COLOR_OFFSET,
         hjust=0,
         fontface="italic",
     )
-    # Region labels
     + geom_text(
         aes(x="x", y="y", label="label"),
         data=df_annotations.query("group == 'region'"),
-        size=12,
-        color="#666666",
+        size=4,
+        color=INK_MUTED,
         fontface="italic",
     )
-    # Styling
-    + labs(
-        x="Engineering Strain",
-        y="Engineering Stress (MPa)",
-        title="line-stress-strain \u00b7 letsplot \u00b7 pyplots.ai",
-    )
+    + labs(x="Engineering Strain", y="Engineering Stress (MPa)", title=title)
     + scale_x_continuous(breaks=[0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35])
     + scale_y_continuous(breaks=[0, 50, 100, 150, 200, 250, 300, 350, 400, 450])
-    + ggsize(1600, 900)
+    + ggsize(800, 450)
     + theme_minimal()
     + theme(
-        axis_text=element_text(size=16, color="#555555"),
-        axis_title=element_text(size=20, color="#333333"),
-        plot_title=element_text(size=24, color="#222222", face="bold"),
+        plot_background=element_rect(fill=PAGE_BG, color=PAGE_BG),
+        panel_background=element_rect(fill=PAGE_BG, color=PAGE_BG),
+        axis_title=element_text(size=12, color=INK),
+        axis_text=element_text(size=10, color=INK_SOFT),
+        plot_title=element_text(size=16, color=INK),
         panel_grid_major_x=element_blank(),
-        panel_grid_major_y=element_line(color="#E0E0E0", size=0.3),
+        panel_grid_major_y=element_line(color=INK_SOFT, size=0.2),
         panel_grid_minor=element_blank(),
-        plot_background=element_rect(fill="#FAFAFA", color="#FAFAFA"),
-        panel_background=element_rect(fill="transparent", color="transparent"),
+        axis_line=element_line(color=INK_SOFT),
         axis_ticks=element_blank(),
         axis_ticks_length=0,
-        plot_margin=[30, 40, 20, 20],
+        plot_margin=[20, 30, 15, 15],
     )
 )
 
 # Save
-export_ggsave(plot, filename="plot.png", path=".", scale=3)
-export_ggsave(plot, filename="plot.html", path=".")
+ggsave(plot, f"plot-{THEME}.png", path=".", scale=4)
+ggsave(plot, f"plot-{THEME}.html", path=".")