Add altair charts

app.py

@@ -6,5 +6,64 @@ from bruges.reflection.reflection import zoeppritz_rpp as zrpp
 import pandas as pd
 import altair as alt
 
-x = st.slider("Select a value")
-st.write(x, "squared is", x*x)
+p = st.slider("Select a value for Poisson's ratio", min_value=0.4, max_value=0.5)
+st.write("Poisson's ratio is:", p)
+
+def vs_from_poisson(vp, poisson):
+    return np.sqrt((vp**2 - 2*poisson*vp**2)/(2 - 2*poisson))
+
+def gardners(vp):
+    return 1000*0.31*np.power(vp, 0.25)/1.33
+
+def cartesian_product(*arrays):
+    ndim = len(arrays)
+    return (np.stack(np.meshgrid(*arrays), axis=-1)
+              .reshape(-1, ndim))
+
+VP1 = np.arange(1530,1820,50)
+THE = np.arange(0.0, 88., 1.)
+POI = np.array([p])
+
+params = cartesian_product(VP1, THE, POI)
+VP1, THE, POI = [a.ravel() for a in np.hsplit(params, 3)]
+
+VP0 = np.full(VP1.shape, 1520.)
+# V-RMS for ~200 m water depth
+VS0 = np.full(VP1.shape, 0.)
+RH0 = np.full(VP1.shape, 1025)
+# 1025 kg/m^3 per Inversion of the physical properties of seafloor surface, South China Sea, Zhou et al 2021
+VP1 = VP1
+VS1 = vs_from_poisson(VP1,POI)
+RH1 = gardners(VP1)
+
+params = {"vp1": VP0, "vs1": VS0, "rho1": RH1,
+          "vp2": VP1, "vs2": VS1, "rho2": RH1,
+          "theta1":THE}
+
+def loop_zrpp(vp1,vs1,rho1,vp2,vs2,rho2,theta1):
+    refl_loop = np.empty(len(vp1), dtype=complex)
+    for i in range(vp1.shape[0]):
+        refl_loop[i] = zrpp(vp1=vp1[i], vs1=vs1[i], rho1=rho1[i],
+                         vp2=vp2[i], vs2=vs2[i], rho2=rho2[i],
+                         theta1=theta1[i])
+    return refl_loop
+
+r = loop_zrpp(**params)
+
+df = pd.DataFrame({"Vp sub-WB": VP1, "Poisson_s ratio": POI,
+                   "Angle": THE, "Amplitude": np.real(r)})
+df["Ang_Crit"] = np.degrees(np.arcsin(1500 / df["Vp sub-WB"].values))
+df = df[df["Angle"] < df["Ang_Crit"]]
+
+chart = alt.Chart(df).mark_line().encode(
+        x="Angle",
+        y="Amplitude",
+        color="Vp sub-WB"
+    ).properties(
+        width=180,
+        height=180
+    ).facet(
+        column='Poisson_s ratio:N'
+    )
+
+st.altair_chart(chart)