ecg / app.py
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import streamlit as st
import numpy as np
import pandas as pd
import tensorflow as tf
import wfdb
import tempfile
import os
from scipy.signal import resample
import matplotlib.pyplot as plt
import cv2
# Custom activation functions
def sin_activation(x):
return tf.math.sin(x)
def cos_activation(x):
return tf.math.cos(x)
# Load model with custom objects
@st.cache_resource
def load_model():
return tf.keras.models.load_model(
"model.keras",
custom_objects={
'sin': sin_activation,
'cos': cos_activation,
'gelu': tf.keras.activations.gelu
}
)
model = load_model()
# AAMI class map
class_map = {
0: "Normal",
1: "Supraventricular Ectopic (SVEB)",
2: "Ventricular Ectopic (VEB)",
3: "Fusion Beat",
4: "Unknown"
}
# Function to extract beats from record
def extract_beats(record, annotation, window_size=257):
beats = []
r_locs = annotation.sample
signal = record.p_signal[:, 0] # Using first channel
for r in r_locs:
start = max(0, r - window_size//2)
end = min(len(signal), r + window_size//2 + 1)
if end - start == window_size:
beat = signal[start:end]
beats.append(beat)
return np.array(beats)
# Function to detect the last Conv1D layer in the model
def get_last_conv_layer_name(model):
last_conv_layer = None
# Loop in reverse order over layers to find a Conv1D layer
for layer in reversed(model.layers):
if isinstance(layer, tf.keras.layers.Conv1D):
last_conv_layer = layer.name
break
if last_conv_layer is None:
st.error("No Conv1D layer found in the model. Grad-CAM requires a convolution layer.")
return last_conv_layer
# Function to generate Grad-CAM heatmap for a given beat and class index
def make_gradcam_heatmap(beat, model, conv_layer_name, class_index):
# Create a model that maps the input beat to the activations of the conv layer and the output predictions
grad_model = tf.keras.models.Model(
[model.inputs],
[model.get_layer(conv_layer_name).output, model.output]
)
# Record operations for automatic differentiation
with tf.GradientTape() as tape:
# Expand dims to add batch axis: shape (1, 257, 1)
beat_tensor = tf.expand_dims(beat, axis=0)
conv_outputs, predictions = grad_model(beat_tensor)
loss = predictions[:, class_index]
# Compute gradients of the target class wrt feature map
grads = tape.gradient(loss, conv_outputs)
# Global average pooling over the time dimension to get weights
weights = tf.reduce_mean(grads, axis=1)
# Compute the weighted sum of feature maps along the channel dimension
cam = tf.reduce_sum(tf.multiply(weights, conv_outputs), axis=-1)
cam = tf.squeeze(cam) # Remove batch dimension
# Apply ReLU to the heatmap to keep only positive influences
heatmap = tf.maximum(cam, 0)
# Normalize heatmap to the [0, 1] range
heatmap_max = tf.reduce_max(heatmap)
if heatmap_max == 0:
heatmap = tf.zeros_like(heatmap)
else:
heatmap /= heatmap_max
heatmap = heatmap.numpy()
# Resize heatmap to match the input beat size (if needed)
# For 1D, we use cv2.resize with the new shape (length, 1) then flatten
heatmap = cv2.resize(heatmap, (beat.shape[0], 1)).flatten()
return heatmap
# Streamlit App Layout
st.title("ECG Arrhythmia Classification with Grad-CAM Visualization")
st.write("Upload MIT-BIH record files (.dat, .hea, .atr) or load record 108")
record_loaded = False
record = None
annotation = None
# Load Record 108 Button
if st.button("Load Record 108"):
try:
base_name = "108"
record = wfdb.rdrecord(base_name)
annotation = wfdb.rdann(base_name, 'atr')
record_loaded = True
except Exception as e:
st.error(f"Error loading Record 108: {str(e)}")
# File uploader
uploaded_files = st.file_uploader(
"Or upload your own files",
type=["dat", "hea", "atr"],
accept_multiple_files=True
)
if uploaded_files and not record_loaded:
with tempfile.TemporaryDirectory() as tmpdir:
for f in uploaded_files:
file_path = os.path.join(tmpdir, f.name)
with open(file_path, "wb") as f_out:
f_out.write(f.getbuffer())
base_names = {os.path.splitext(f.name)[0] for f in uploaded_files}
common_base = list(base_names)[0]
try:
record = wfdb.rdrecord(os.path.join(tmpdir, common_base))
annotation = wfdb.rdann(os.path.join(tmpdir, common_base), 'atr')
record_loaded = True
except Exception as e:
st.error(f"Error reading uploaded files: {str(e)}")
# Process the record if loaded
if record_loaded and record is not None and annotation is not None:
beats = extract_beats(record, annotation)
if len(beats) == 0:
st.error("No valid beats found in the record")
st.stop()
beats = beats.reshape((-1, 257, 1)).astype(np.float32)
predictions = model.predict(beats)
predicted_classes = np.argmax(predictions, axis=1)
st.subheader("Classification Results")
results = pd.DataFrame({
"Beat Index": range(len(beats)),
"Predicted Class": [class_map[c] for c in predicted_classes],
"Confidence": np.max(predictions, axis=1)
})
st.dataframe(results)
# Class Distribution Section
st.subheader("Class Distribution")
class_indices = list(class_map.keys())
class_names = [class_map[i] for i in class_indices]
counts = [np.sum(predicted_classes == i) for i in class_indices]
distribution_df = pd.DataFrame({
"Class": class_names,
"Count": counts
})
col1, col2 = st.columns([1, 2])
with col1:
st.dataframe(distribution_df.style.format({'Count': '{:,}'}))
with col2:
st.bar_chart(distribution_df.set_index('Class'))
# Display a Sample ECG Beat
st.subheader("Sample ECG Beat")
fig, ax = plt.subplots()
ax.plot(beats[0].flatten(), label="ECG Beat")
ax.legend()
st.pyplot(fig)
# ---------------- Grad-CAM Visualization Section ----------------
st.subheader("Grad-CAM Heatmap Visualization for Each Beat")
st.write("Below are Grad-CAM heatmaps overlaying each beat. The heatmaps show the regions contributing most to the predicted class.")
# Automatically detect the last convolutional layer name
conv_layer_name = get_last_conv_layer_name(model)
if conv_layer_name is not None:
st.write(f"Using Conv1D layer: **{conv_layer_name}** for Grad-CAM.")
# Optionally, you can limit the number of beats displayed to avoid long processing times.
# For demonstration, here we process all beats, but you might want to show only the first N beats.
show_all = st.checkbox("Show Grad-CAM for all beats", value=False)
if not show_all:
num_beats_to_show = st.number_input("Number of beats to show:", min_value=1, max_value=len(beats), value=5)
else:
num_beats_to_show = len(beats)
# Loop over each beat and its prediction to generate Grad-CAM heatmap
for idx in range(num_beats_to_show):
beat = beats[idx]
pred_class = predicted_classes[idx]
predicted_label = class_map[pred_class]
# Compute Grad-CAM heatmap for the beat
heatmap = make_gradcam_heatmap(beat, model, conv_layer_name, pred_class)
# Generate visualization figure
fig, ax = plt.subplots(figsize=(10, 3))
# Plot the raw ECG beat
ax.plot(beat.flatten(), color="black", label="ECG Beat")
# Overlay Grad-CAM heatmap by scatter plotting points with a colormap according to heatmap value
sc = ax.scatter(np.arange(len(beat)), beat.flatten(), c=heatmap, cmap="jet", s=25)
ax.set_title(f"Beat {idx} - Predicted: {predicted_label}")
ax.set_xlabel("Time Index")
ax.set_ylabel("Amplitude")
# Add a colorbar to indicate heatmap intensity
fig.colorbar(sc, ax=ax, label="Grad-CAM Intensity")
st.pyplot(fig)