script dump

extrapolation_blow-up.py

@@ -0,0 +1,66 @@
+import numpy as np
+import matplotlib.pyplot as plt
+
+# -----------------------------
+# Fake but realistic SFs
+# -----------------------------
+np.random.seed(1)
+
+n_ref = 30
+
+# Apo structure factors
+Fa_amp = np.random.uniform(50, 200, n_ref)
+Fa_phi = np.random.uniform(-np.pi, np.pi, n_ref)
+Fa = Fa_amp * np.exp(1j * Fa_phi)
+
+# Difference signal (e.g. ligand / backbone change)
+dF_amp = np.random.uniform(5, 40, n_ref)
+dF_phi = Fa_phi + np.random.normal(0, 0.4, n_ref)
+dF = dF_amp * np.exp(1j * dF_phi)
+
+# Mixed data
+Fab = Fa + dF
+
+# -----------------------------
+# Choose occupancies
+# -----------------------------
+b_values = [1.0, 0.5, 0.2, 0.1]
+
+# -----------------------------
+# Plot
+# -----------------------------
+fig, axes = plt.subplots(2, len(b_values), figsize=(14, 6), sharex=True, sharey=True)
+
+for i, b in enumerate(b_values):
+    Fb = Fa + (Fab - Fa) / b          # extrapolated SF
+    dF_scaled = (Fab - Fa) / b        # pure difference term
+
+    # ----- Extrapolated vectors -----
+    ax = axes[0, i]
+    ax.set_title(f"Fb extrapolated (b={b})")
+    for z in Fb:
+        ax.arrow(0, 0, z.real, z.imag,
+                 head_width=2, length_includes_head=True,
+                 alpha=0.6)
+    ax.axhline(0, color='grey', lw=0.5)
+    ax.axvline(0, color='grey', lw=0.5)
+    ax.set_aspect('equal')
+
+    # ----- Difference vectors -----
+    ax = axes[1, i]
+    ax.set_title("ΔF / b")
+    for z in dF_scaled:
+        ax.arrow(0, 0, z.real, z.imag,
+                 head_width=2, length_includes_head=True,
+                 alpha=0.6, color='crimson')
+    ax.axhline(0, color='grey', lw=0.5)
+    ax.axvline(0, color='grey', lw=0.5)
+    ax.set_aspect('equal')
+
+axes[0, 0].set_ylabel("Imag(F)")
+axes[1, 0].set_ylabel("Imag(F)")
+for ax in axes[1]:
+    ax.set_xlabel("Real(F)")
+
+plt.tight_layout()
+plt.show()