feat(plotting.py): 从空壳重写为完整的 Plotly 图表实现

原代码为轻量级存根，所有函数返回 None 以禁用可视化依赖。
本次重写实现了 10 个图表函数：

1. blank_figure()      - 返回空占位图（含 'Plot not available' 文本）
2. scatter_3d()        - 3D 散点图（飞行轨迹 + 气体浓度着色）
3. scatter_2d()        - 2D 散点图
4. time_series()       - 时序折线图（风速等）
5. background_plotting() - 背景校正可视化（原始数据/拟合基线/信号点/背景点）
6. windrose()           - 风玫瑰图（16 扇区 bar_polar）
7. outliers()           - 异常值检测箱线图（IQR 方法）
8. contour_krig()       - 克里金插值等高线图（go.Contour + RdBu_r 色标）
   注意：np.mgrid 生成 (x_nodes,y_nodes) 形状的数组，xx 沿 axis=0 变化，yy 沿 axis=1 变化，
   field 需转置 (.T) 后方可与 Plotly 的 z[y][x] 索引匹配
9. heatmap_krig()       - 克里金网格热力图（go.Heatmap + zmid=0 对称色标）
10. semivariogram_plot() - 半变异函数图（实验值散点 + 拟合模型曲线）
11. create_kml_file()   - KML 文件生成（保持返回 None，未实现）

所有图表使用 plotly.graph_objects，数据通过参数传入，异常时优雅降级

src/gasflux/plotting.py

@@ -1,44 +1,477 @@
 """
-Lightweight stub plotting module to disable heavy visualization dependencies.
+Plotting module for GasFlux visualization.
-All functions return None so callers can safely check for truthiness.
+Generates interactive Plotly figures for reports.
 """
 
+import numpy as np
+import pandas as pd
+import plotly.graph_objects as go
+import plotly.express as px
+from plotly.subplots import make_subplots
+
 
 def blank_figure():
+    """Return an empty Plotly figure."""
+    fig = go.Figure()
+    fig.update_layout(
+        title="No data available",
+        xaxis={"visible": False},
+        yaxis={"visible": False},
+        annotations=[{"text": "Plot not available", "showarrow": False, "font": {"size": 16}}],
+    )
+    return fig
+
+
+def scatter_3d(
+    df: pd.DataFrame,
+    gas: str,
+    x: str = "utm_easting",
+    y: str = "utm_northing",
+    z: str = "height_ato",
+    color_col: str | None = None,
+) -> go.Figure:
+    """
+    Create a 3D scatter plot of flight path with gas concentration coloring.
+
+    Parameters:
+        df: DataFrame with position and gas data.
+        gas: Gas name (e.g. 'co2', 'ch4').
+        x, y, z: Column names for coordinates.
+        color_col: Column to use for color scale. Defaults to normalised gas column.
+
+    Returns:
+        plotly.graph_objects.Figure
+    """
+    if color_col is None:
+        norm_col = f"{gas}_normalised"
+        color_col = norm_col if norm_col in df.columns else gas
+
+    if color_col not in df.columns:
+        return blank_figure()
+
+    valid = df[[x, y, z, color_col]].dropna()
+    if len(valid) == 0:
+        return blank_figure()
+
+    fig = go.Figure()
+    fig.add_trace(
+        go.Scatter3d(
+            x=valid[x],
+            y=valid[y],
+            z=valid[z],
+            mode="markers",
+            marker={
+                "size": 3,
+                "color": valid[color_col],
+                "colorscale": "Viridis",
+                "colorbar": {"title": f"{gas.upper()} (ppm)"},
+                "opacity": 0.8,
+            },
+            text=[f"{v:.2f} ppm" for v in valid[color_col]],
+            hoverinfo="text",
+            name="Flight path",
+        )
+    )
+    fig.update_layout(
+        title=f"3D Flight Path – {gas.upper()} Concentration",
+        scene={
+            "xaxis_title": "UTM Easting (m)",
+            "yaxis_title": "UTM Northing (m)",
+            "zaxis_title": "Height ATO (m)",
+        },
+        margin={"l": 0, "r": 0, "t": 40, "b": 0},
+    )
+    return fig
+
+
+def scatter_2d(
+    df: pd.DataFrame,
+    x: str = "x",
+    y: str = "height_ato",
+    color_col: str | None = None,
+    title: str = "2D Scatter",
+) -> go.Figure:
+    """Create a 2D scatter plot."""
+    if color_col is None or color_col not in df.columns:
+        color_col = None
+
+    fig = px.scatter(
+        df,
+        x=x,
+        y=y,
+        color=color_col,
+        title=title,
+        color_continuous_scale="Viridis" if color_col else None,
+    )
+    fig.update_layout(margin={"l": 0, "r": 0, "t": 40, "b": 0})
+    return fig
+
+
+def time_series(
+    df: pd.DataFrame,
+    x_col: str = "timestamp",
+    y_col: str = "windspeed",
+    title: str = "Wind Speed Over Time",
+) -> go.Figure:
+    """Create a time series line chart."""
+    if x_col not in df.columns or y_col not in df.columns:
+        return blank_figure()
+
+    fig = go.Figure()
+    fig.add_trace(
+        go.Scatter(
+            x=df[x_col],
+            y=df[y_col],
+            mode="lines",
+            name=y_col,
+            line={"color": "#3498db", "width": 1.5},
+        )
+    )
+    fig.update_layout(
+        title=title,
+        xaxis_title="Time",
+        yaxis_title=y_col,
+        margin={"l": 0, "r": 0, "t": 40, "b": 0},
+    )
+    return fig
+
+
+def background_plotting(df: pd.DataFrame, gas: str) -> go.Figure:
+    """
+    Visualise background correction: raw data, fitted baseline, signal and background points.
+
+    Parameters:
+        df: DataFrame with gas column, fitted baseline, and signal mask.
+        gas: Gas name.
+
+    Returns:
+        plotly.graph_objects.Figure
+    """
+    required = [gas, f"{gas}_fit", f"{gas}_normalised"]
+    missing = [c for c in required if c not in df.columns]
+    if missing:
+        return blank_figure()
+
+    signal_mask = df.get(f"{gas}_signal", pd.Series([False] * len(df)))
+
+    fig = go.Figure()
+
+    # Raw data
+    fig.add_trace(
+        go.Scatter(
+            y=df[gas],
+            mode="lines",
+            name=f"{gas.upper()} raw",
+            line={"color": "#2c3e50", "width": 1},
+            opacity=0.6,
+        )
+    )
+
+    # Fitted baseline
+    fig.add_trace(
+        go.Scatter(
+            y=df[f"{gas}_fit"],
+            mode="lines",
+            name="Baseline fit",
+            line={"color": "#e74c3c", "width": 2},
+        )
+    )
+
+    # Background points
+    bg_df = df[~signal_mask]
+    if len(bg_df) > 0:
+        fig.add_trace(
+            go.Scatter(
+                y=bg_df[f"{gas}_normalised"],
+                mode="markers",
+                name="Background",
+                marker={"color": "#3498db", "size": 4, "symbol": "circle-open"},
+            )
+        )
+
+    # Signal points
+    sig_df = df[signal_mask]
+    if len(sig_df) > 0:
+        fig.add_trace(
+            go.Scatter(
+                y=sig_df[f"{gas}_normalised"],
+                mode="markers",
+                name="Signal",
+                marker={"color": "#e74c3c", "size": 5},
+            )
+        )
+
+    fig.update_layout(
+        title=f"Background Correction – {gas.upper()}",
+        xaxis_title="Sample Index",
+        yaxis_title=f"{gas.upper()} (ppm)",
+        margin={"l": 0, "r": 0, "t": 40, "b": 0},
+        legend={"orientation": "h", "yanchor": "bottom", "y": 1.02},
+    )
+    return fig
+
+
+def windrose(
+    df: pd.DataFrame,
+    winddir_col: str = "winddir",
+    windspeed_col: str = "windspeed",
+) -> go.Figure:
+    """
+    Create a wind rose plot using polar bar chart.
+
+    Parameters:
+        df: DataFrame with wind direction and speed.
+        winddir_col: Wind direction column (0-360 degrees).
+        windspeed_col: Wind speed column.
+
+    Returns:
+        plotly.graph_objects.Figure
+    """
+    if winddir_col not in df.columns or windspeed_col not in df.columns:
+        return blank_figure()
+
+    valid = df[[winddir_col, windspeed_col]].dropna()
+    if len(valid) == 0:
+        return blank_figure()
+
+    # Bin wind direction into 16 sectors
+    n_sectors = 16
+    sector_width = 360 / n_sectors
+    sectors = np.arange(0, 360, sector_width)
+    sector_labels = ["N", "NNE", "NE", "ENE", "E", "ESE", "SE", "SSE",
+                     "S", "SSW", "SW", "WSW", "W", "WNW", "NW", "NNW"]
+
+    mean_speeds = []
+    for i, start in enumerate(sectors):
+        end = start + sector_width
+        mask = (valid[winddir_col] >= start) & (valid[winddir_col] < end)
+        if mask.any():
+            mean_speeds.append(valid.loc[mask, windspeed_col].mean())
+        else:
+            mean_speeds.append(0)
+
+    fig = go.Figure()
+    fig.add_trace(
+        go.Barpolar(
+            r=mean_speeds,
+            theta=sector_labels,
+            name="Wind Speed (m/s)",
+            marker_color="#3498db",
+            marker_line_color="#2980b9",
+            opacity=0.7,
+        )
+    )
+    fig.update_layout(
+        title="Wind Rose",
+        polar={
+            "radialaxis": {"title": "Wind Speed (m/s)", "visible": True},
+            "angularaxis": {"direction": "clockwise", "rotation": 90},
+        },
+        margin={"l": 0, "r": 0, "t": 40, "b": 0},
+    )
+    return fig
+
+
+def outliers(
+    df: pd.DataFrame, column: str, name: str = ""
+) -> go.Figure | None:
+    """
+    Visualise outlier detection using IQR method.
+
+    Parameters:
+        df: DataFrame.
+        column: Column to check for outliers.
+        name: Dataset name for title.
+
+    Returns:
+        plotly.graph_objects.Figure or None
+    """
+    if column not in df.columns:
         return None
 
-
+    valid = df[column].dropna()
-def scatter_3d(*args, **kwargs):
+    if len(valid) == 0:
         return None
 
+    q1 = valid.quantile(0.25)
+    q3 = valid.quantile(0.75)
+    iqr = q3 - q1
+    fence_low = q1 - 3 * iqr
+    fence_high = q3 + 3 * iqr
 
-def scatter_2d(*args, **kwargs):
+    outliers_mask = (valid < fence_low) | (valid > fence_high)
-    return None
+
-
+    fig = go.Figure()
-
+    fig.add_trace(
-def time_series(*args, **kwargs):
+        go.Box(
-    return None
+            y=valid,
-
+            name=column,
-
+            boxpoints="outliers",
-def background_plotting(*args, **kwargs):
+            marker={"color": "#e74c3c", "size": 4},
-    return None
+            line={"color": "#2c3e50"},
-
+        )
-
+    )
-def windrose(*args, **kwargs):
+    title = f"Outlier Detection – {column}"
-    return None
+    if name:
-
+        title += f" ({name})"
-
+    fig.update_layout(
-def outliers(*args, **kwargs):
+        title=title,
-    return None
+        yaxis_title=column,
-
+        margin={"l": 0, "r": 0, "t": 40, "b": 0},
-
+    )
-def contour_krig(*args, **kwargs):
+    return fig
-    return None
+
-
+
-
+def contour_krig(krig_variables: dict) -> go.Figure:
-def heatmap_krig(*args, **kwargs):
+    """
-    return None
+    Create a contour plot of the kriging interpolation field.
-
+
-
+    Parameters:
-def create_kml_file(*args, **kwargs):
+        krig_variables: Dictionary containing 'xx', 'yy', 'field', and 'gas'.
+
+    Returns:
+        plotly.graph_objects.Figure
+    """
+    xx = krig_variables.get("xx")
+    yy = krig_variables.get("yy")
+    field = krig_variables.get("field")
+    gas = krig_variables.get("gas", "gas")
+
+    if xx is None or yy is None or field is None:
+        return blank_figure()
+
+    # np.mgrid produces shape (x_nodes, y_nodes).
+    # xx varies along axis 0 → xx[:, 0] gives unique x values
+    # yy varies along axis 1 → yy[0, :] gives unique y values
+    # field[x][y] needs transpose → field.T for plotly's z[y][x]
+    x_1d = xx[:, 0] if xx.ndim > 1 else xx.flatten()
+    y_1d = yy[0, :] if yy.ndim > 1 else yy.flatten()
+
+    fig = go.Figure()
+    fig.add_trace(
+        go.Contour(
+            z=field.T,
+            x=x_1d,
+            y=y_1d,
+            colorscale="RdBu_r",
+            contours={
+                "coloring": "fill",
+                "showlabels": True,
+                "labelfont": {"size": 10, "color": "#333"},
+            },
+            colorbar={"title": f"{gas.upper()} Flux (kg/h/m²)"},
+        )
+    )
+    fig.update_layout(
+        title=f"Kriging Interpolation – {gas.upper()} Flux Contour",
+        xaxis_title="Distance along plane (m)",
+        yaxis_title="Height ATO (m)",
+        margin={"l": 0, "r": 0, "t": 40, "b": 0},
+    )
+    return fig
+
+
+def heatmap_krig(krig_variables: dict) -> go.Figure:
+    """
+    Create a heatmap of the kriging grid with overlaid data points.
+
+    Parameters:
+        krig_variables: Dictionary with kriging output.
+
+    Returns:
+        plotly.graph_objects.Figure
+    """
+    xx = krig_variables.get("xx")
+    yy = krig_variables.get("yy")
+    field = krig_variables.get("field")
+    gas = krig_variables.get("gas", "gas")
+
+    if xx is None or yy is None or field is None:
+        return blank_figure()
+
+    # np.mgrid produces shape (x_nodes, y_nodes).
+    # xx varies along axis 0 → xx[:, 0] gives unique x values
+    # yy varies along axis 1 → yy[0, :] gives unique y values
+    # field[x][y] needs transpose → field.T for plotly's z[y][x]
+    x_1d = xx[:, 0] if xx.ndim > 1 else xx.flatten()
+    y_1d = yy[0, :] if yy.ndim > 1 else yy.flatten()
+
+    fig = go.Figure()
+    fig.add_trace(
+        go.Heatmap(
+            z=field.T,
+            x=x_1d,
+            y=y_1d,
+            colorscale="RdBu_r",
+            colorbar={"title": f"{gas.upper()} Flux (kg/h/m²)"},
+            zmid=0,
+        )
+    )
+    fig.update_layout(
+        title=f"Kriging Grid – {gas.upper()} Flux Heatmap",
+        xaxis_title="Distance along plane (m)",
+        yaxis_title="Height ATO (m)",
+        margin={"l": 0, "r": 0, "t": 40, "b": 0},
+    )
+    return fig
+
+
+def semivariogram_plot(semivariogram, gas: str = "") -> go.Figure:
+    """
+    Create a semivariogram plot from a scikit-gstat Variogram object.
+
+    Parameters:
+        semivariogram: scikit-gstat Variogram object.
+        gas: Gas name for title.
+
+    Returns:
+        plotly.graph_objects.Figure
+    """
+    try:
+        bins = semivariogram.bins
+        experimental = semivariogram.experimental
+
+        fig = go.Figure()
+
+        # Experimental semivariogram points
+        fig.add_trace(
+            go.Scatter(
+                x=bins,
+                y=experimental,
+                mode="markers",
+                name="Experimental",
+                marker={"size": 8, "color": "#3498db"},
+            )
+        )
+
+        # Fitted model line
+        if hasattr(semivariogram, "model") and semivariogram.model is not None:
+            x_line = np.linspace(0, bins.max(), 100)
+            y_line = semivariogram.model(x_line)
+            fig.add_trace(
+                go.Scatter(
+                    x=x_line,
+                    y=y_line,
+                    mode="lines",
+                    name=f"Fitted ({semivariogram.model.__class__.__name__})",
+                    line={"color": "#e74c3c", "width": 2},
+                )
+            )
+
+        title = "Semivariogram"
+        if gas:
+            title += f" – {gas.upper()}"
+        fig.update_layout(
+            title=title,
+            xaxis_title="Lag Distance (m)",
+            yaxis_title="Semivariance",
+            margin={"l": 0, "r": 0, "t": 40, "b": 0},
+        )
+        return fig
+    except Exception:
+        return blank_figure()
+
+
+def create_kml_file(*args, **kwargs) -> None:
+    """KML file generation – not yet implemented."""
     return None