Update app.py

app.py

@@ -0,0 +1,168 @@
+import streamlit as st
+import numpy as np
+import math
+import pandas as pd
+import matplotlib.pyplot as plt
+
+st.set_page_config(page_title="Advanced Calculator", layout="centered")
+
+st.title("🧮 Advanced Calculator")
+st.markdown("Multi-feature calculator for Hugging Face Streamlit deployment")
+
+# -------------------------------
+# Safe Expression Evaluation
+# -------------------------------
+allowed_names = {
+    k: getattr(math, k) for k in dir(math) if not k.startswith("_")
+}
+allowed_names.update({
+    "np": np,
+    "abs": abs,
+    "round": round
+})
+
+def safe_eval(expr):
+    try:
+        return eval(expr, {"__builtins__": {}}, allowed_names)
+    except Exception as e:
+        return f"Error: {e}"
+
+# -------------------------------
+# Sidebar Navigation
+# -------------------------------
+option = st.sidebar.selectbox(
+    "Select Calculator Mode",
+    ["Basic / Scientific", "Unit Converter", "Function Plotter", "History"]
+)
+
+# Session history
+if "history" not in st.session_state:
+    st.session_state.history = []
+
+# -------------------------------
+# BASIC & SCIENTIFIC CALCULATOR
+# -------------------------------
+if option == "Basic / Scientific":
+    st.subheader("Basic & Scientific Calculator")
+
+    expr = st.text_input(
+        "Enter mathematical expression",
+        placeholder="Example: sin(pi/2) + log(10)"
+    )
+
+    if st.button("Calculate"):
+        result = safe_eval(expr)
+        st.write("### Result:", result)
+
+        st.session_state.history.append({
+            "Expression": expr,
+            "Result": result
+        })
+
+# -------------------------------
+# UNIT CONVERTER
+# -------------------------------
+elif option == "Unit Converter":
+    st.subheader("Unit Converter")
+
+    conversion_type = st.selectbox(
+        "Select Conversion Type",
+        ["Length", "Weight", "Temperature"]
+    )
+
+    value = st.number_input("Enter Value")
+
+    if conversion_type == "Length":
+        units = st.selectbox("Convert From", ["Meters", "Kilometers", "Miles"])
+        target = st.selectbox("Convert To", ["Meters", "Kilometers", "Miles"])
+
+        conversion = {
+            "Meters": 1,
+            "Kilometers": 1000,
+            "Miles": 1609.34
+        }
+
+        result = value * conversion[units] / conversion[target]
+        st.write("### Result:", result)
+
+    elif conversion_type == "Weight":
+        units = st.selectbox("Convert From", ["Grams", "Kilograms", "Pounds"])
+        target = st.selectbox("Convert To", ["Grams", "Kilograms", "Pounds"])
+
+        conversion = {
+            "Grams": 1,
+            "Kilograms": 1000,
+            "Pounds": 453.592
+        }
+
+        result = value * conversion[units] / conversion[target]
+        st.write("### Result:", result)
+
+    elif conversion_type == "Temperature":
+        units = st.selectbox("Convert From", ["Celsius", "Fahrenheit", "Kelvin"])
+        target = st.selectbox("Convert To", ["Celsius", "Fahrenheit", "Kelvin"])
+
+        def temp_convert(val, u, t):
+            if u == t:
+                return val
+
+            # Convert to Celsius first
+            if u == "Fahrenheit":
+                val = (val - 32) * 5/9
+            elif u == "Kelvin":
+                val = val - 273.15
+
+            # Convert from Celsius to target
+            if t == "Fahrenheit":
+                return val * 9/5 + 32
+            elif t == "Kelvin":
+                return val + 273.15
+            return val
+
+        st.write("### Result:", temp_convert(value, units, target))
+
+# -------------------------------
+# FUNCTION PLOTTER
+# -------------------------------
+elif option == "Function Plotter":
+    st.subheader("Function Plotter")
+
+    func_expr = st.text_input(
+        "Enter function in terms of x",
+        placeholder="Example: sin(x) or x**2 + 3*x"
+    )
+
+    x_min = st.number_input("X min", value=-10.0)
+    x_max = st.number_input("X max", value=10.0)
+
+    if st.button("Plot Function"):
+        try:
+            x = np.linspace(x_min, x_max, 400)
+            y = eval(func_expr, {"__builtins__": {}}, {**allowed_names, "x": x})
+
+            fig, ax = plt.subplots()
+            ax.plot(x, y)
+            ax.set_xlabel("x")
+            ax.set_ylabel("y")
+            ax.set_title(f"Plot of {func_expr}")
+            ax.grid(True)
+
+            st.pyplot(fig)
+
+        except Exception as e:
+            st.error(f"Plot Error: {e}")
+
+# -------------------------------
+# HISTORY
+# -------------------------------
+elif option == "History":
+    st.subheader("Calculation History")
+
+    if st.session_state.history:
+        df = pd.DataFrame(st.session_state.history)
+        st.dataframe(df, use_container_width=True)
+
+        if st.button("Clear History"):
+            st.session_state.history = []
+    else:
+        st.info("No calculations yet.")