# Why my CNN model is not learning?

I want to train a model to predict one's emotion from the physical signals. I have a physical signal and using it as input feature;

ecg(Electrocardiography)

In my dataset, there are 312 total records belonging to the participants and there are 18000 rows of data in each record. So when I combine them into a single data frame, there are 5616000 rows in total.

Here is my train_x dataframe;

            ecg
0        0.1912
1        0.3597
2        0.3597
3        0.3597
4        0.3597
5        0.3597
6        0.2739
7        0.1641
8        0.0776
9        0.0005
10      -0.0375
11      -0.0676
12      -0.1071
13      -0.1197
..      .......
..      .......
..      .......
5616000 0.0226


And I have 6 classes which are corresponding to emotions. I have encoded these labels with numbers;

anger = 0, calmness = 1, disgust = 2, fear = 3, happiness = 4, sadness = 5

Here is my train_y;

         emotion
0              0
1              0
2              0
3              0
4              0
.              .
.              .
.              .
18001          1
18002          1
18003          1
.              .
.              .
.              .
360001         2
360002         2
360003         2
.              .
.              .
.              .
.              .
5616000        5


To feed my CNN, I am reshaping the train_x and one hot encoding the train_y data.

train_x = train_x.values.reshape(312,18000,1)
train_y = train_y.values.reshape(312,18000)
train_y = train_y[:,:1]  # truncated train_y to have single corresponding value to a complete signal.
train_y = pd.DataFrame(train_y)
train_y = pd.get_dummies(train_y[0]) #one hot encoded labels


After these processes, here is how they look like; train_x after reshape;

[[[0.60399908]
[0.79763273]
[0.79763273]
...
[0.09779361]
[0.09779361]
[0.14732245]]

[[0.70386905]
[0.95101687]
[0.95101687]
...
[0.41530258]
[0.41728671]
[0.42261905]]

[[0.75008021]
[1.        ]
[1.        ]
...
[0.46412148]
[0.46412148]
[0.46412148]]

...

[[0.60977509]
[0.7756791 ]
[0.7756791 ]
...
[0.12725148]
[0.02755331]
[0.02755331]]

[[0.59939494]
[0.75514785]
[0.75514785]
...
[0.0391334 ]
[0.0391334 ]
[0.0578706 ]]

[[0.5786066 ]
[0.71539303]
[0.71539303]
...
[0.41355098]
[0.41355098]
[0.4112712 ]]]


train_y after one hot encoding;

    0  1  2  3  4  5
0    1  0  0  0  0  0
1    1  0  0  0  0  0
2    0  1  0  0  0  0
3    0  1  0  0  0  0
4    0  0  0  0  0  1
5    0  0  0  0  0  1
6    0  0  1  0  0  0
7    0  0  1  0  0  0
8    0  0  0  1  0  0
9    0  0  0  1  0  0
10   0  0  0  0  1  0
11   0  0  0  0  1  0
12   0  0  0  1  0  0
13   0  0  0  1  0  0
14   0  1  0  0  0  0
15   0  1  0  0  0  0
16   1  0  0  0  0  0
17   1  0  0  0  0  0
18   0  0  1  0  0  0
19   0  0  1  0  0  0
20   0  0  0  0  1  0
21   0  0  0  0  1  0
22   0  0  0  0  0  1
23   0  0  0  0  0  1
24   0  0  0  0  0  1
25   0  0  0  0  0  1
26   0  0  1  0  0  0
27   0  0  1  0  0  0
28   0  1  0  0  0  0
29   0  1  0  0  0  0
..  .. .. .. .. .. ..
282  0  0  0  1  0  0
283  0  0  0  1  0  0
284  1  0  0  0  0  0
285  1  0  0  0  0  0
286  0  0  0  0  1  0
287  0  0  0  0  1  0
288  1  0  0  0  0  0
289  1  0  0  0  0  0
290  0  1  0  0  0  0
291  0  1  0  0  0  0
292  0  0  0  1  0  0
293  0  0  0  1  0  0
294  0  0  1  0  0  0
295  0  0  1  0  0  0
296  0  0  0  0  0  1
297  0  0  0  0  0  1
298  0  0  0  0  1  0
299  0  0  0  0  1  0
300  0  0  0  1  0  0
301  0  0  0  1  0  0
302  0  0  1  0  0  0
303  0  0  1  0  0  0
304  0  0  0  0  0  1
305  0  0  0  0  0  1
306  0  1  0  0  0  0
307  0  1  0  0  0  0
308  0  0  0  0  1  0
309  0  0  0  0  1  0
310  1  0  0  0  0  0
311  1  0  0  0  0  0

[312 rows x 6 columns]


After reshaping, I have created my CNN model;

model = Sequential()
model.add(Conv1D(100,700,activation='relu',input_shape=(18000,1))) #kernel_size is 700 because 18000 rows = 60 seconds so 700 rows = ~2.33 seconds and there is two heart beat peak in every 2 second for ecg signal.

model.compile(optimizer = adam, loss = 'categorical_crossentropy', metrics = ['acc'])
model.fit(train_x,train_y,epochs = 50, batch_size = 32, validation_split=0.33, shuffle=False)


The problem is, accuracy is not going more than 0.2 and it is fluctuating up and down. Looks like the model does not learn anything. I have tried to increase layers, play with the learning rate, changing the loss function, changing the optimizer, scaling the data, normalizing the data, but nothing helped me to solve this problem.

How Can I solve this problem? Thanks in advance.

I wanted to add the training results after 50 epochs;

Epoch 1/80
249/249 [==============================] - 24s 96ms/step - loss: 2.3118 - acc: 0.1406 - val_loss: 1.7989 - val_acc: 0.1587
Epoch 2/80
249/249 [==============================] - 19s 76ms/step - loss: 2.0468 - acc: 0.1647 - val_loss: 1.8605 - val_acc: 0.2222
Epoch 3/80
249/249 [==============================] - 19s 76ms/step - loss: 1.9562 - acc: 0.1767 - val_loss: 1.8203 - val_acc: 0.2063
Epoch 4/80
249/249 [==============================] - 19s 75ms/step - loss: 1.9361 - acc: 0.2169 - val_loss: 1.8033 - val_acc: 0.1905
Epoch 5/80
249/249 [==============================] - 19s 74ms/step - loss: 1.8834 - acc: 0.1847 - val_loss: 1.8198 - val_acc: 0.2222
Epoch 6/80
249/249 [==============================] - 19s 75ms/step - loss: 1.8278 - acc: 0.2410 - val_loss: 1.7961 - val_acc: 0.1905
Epoch 7/80
249/249 [==============================] - 19s 75ms/step - loss: 1.8022 - acc: 0.2450 - val_loss: 1.8092 - val_acc: 0.2063
Epoch 8/80
249/249 [==============================] - 19s 75ms/step - loss: 1.7959 - acc: 0.2369 - val_loss: 1.8005 - val_acc: 0.2222
Epoch 9/80
249/249 [==============================] - 19s 75ms/step - loss: 1.7234 - acc: 0.2610 - val_loss: 1.7871 - val_acc: 0.2381
Epoch 10/80
249/249 [==============================] - 19s 75ms/step - loss: 1.6861 - acc: 0.2972 - val_loss: 1.8017 - val_acc: 0.1905
Epoch 11/80
249/249 [==============================] - 19s 75ms/step - loss: 1.6696 - acc: 0.3173 - val_loss: 1.7878 - val_acc: 0.1905
Epoch 12/80
249/249 [==============================] - 19s 75ms/step - loss: 1.5868 - acc: 0.3655 - val_loss: 1.7771 - val_acc: 0.1270
Epoch 13/80
249/249 [==============================] - 19s 75ms/step - loss: 1.5751 - acc: 0.3936 - val_loss: 1.7818 - val_acc: 0.1270
Epoch 14/80
249/249 [==============================] - 19s 75ms/step - loss: 1.5647 - acc: 0.3735 - val_loss: 1.7733 - val_acc: 0.1429
Epoch 15/80
249/249 [==============================] - 19s 75ms/step - loss: 1.4621 - acc: 0.4177 - val_loss: 1.7759 - val_acc: 0.1270
Epoch 16/80
249/249 [==============================] - 19s 75ms/step - loss: 1.4519 - acc: 0.4498 - val_loss: 1.8005 - val_acc: 0.1746
Epoch 17/80
249/249 [==============================] - 19s 75ms/step - loss: 1.4489 - acc: 0.4378 - val_loss: 1.8020 - val_acc: 0.1270
Epoch 18/80
249/249 [==============================] - 19s 75ms/step - loss: 1.4449 - acc: 0.4297 - val_loss: 1.7852 - val_acc: 0.1587
Epoch 19/80
249/249 [==============================] - 19s 75ms/step - loss: 1.3600 - acc: 0.5301 - val_loss: 1.7922 - val_acc: 0.1429
Epoch 20/80
249/249 [==============================] - 19s 75ms/step - loss: 1.3349 - acc: 0.5422 - val_loss: 1.8061 - val_acc: 0.2222
Epoch 21/80
249/249 [==============================] - 19s 75ms/step - loss: 1.2885 - acc: 0.5622 - val_loss: 1.8235 - val_acc: 0.1746
Epoch 22/80
249/249 [==============================] - 19s 75ms/step - loss: 1.2291 - acc: 0.5823 - val_loss: 1.8173 - val_acc: 0.1905
Epoch 23/80
249/249 [==============================] - 19s 75ms/step - loss: 1.1890 - acc: 0.6506 - val_loss: 1.8293 - val_acc: 0.1905
Epoch 24/80
249/249 [==============================] - 19s 75ms/step - loss: 1.1473 - acc: 0.6627 - val_loss: 1.8274 - val_acc: 0.1746
Epoch 25/80
249/249 [==============================] - 19s 75ms/step - loss: 1.1060 - acc: 0.6747 - val_loss: 1.8142 - val_acc: 0.1587
Epoch 26/80
249/249 [==============================] - 19s 75ms/step - loss: 1.0210 - acc: 0.7510 - val_loss: 1.8126 - val_acc: 0.1905
Epoch 27/80
249/249 [==============================] - 19s 75ms/step - loss: 0.9699 - acc: 0.7631 - val_loss: 1.8094 - val_acc: 0.1746
Epoch 28/80
249/249 [==============================] - 19s 75ms/step - loss: 0.9127 - acc: 0.8193 - val_loss: 1.8012 - val_acc: 0.1746
Epoch 29/80
249/249 [==============================] - 19s 75ms/step - loss: 0.9176 - acc: 0.7871 - val_loss: 1.8371 - val_acc: 0.1746
Epoch 30/80
249/249 [==============================] - 19s 75ms/step - loss: 0.8725 - acc: 0.8233 - val_loss: 1.8215 - val_acc: 0.1587
Epoch 31/80
249/249 [==============================] - 19s 75ms/step - loss: 0.8316 - acc: 0.8514 - val_loss: 1.8010 - val_acc: 0.1429
Epoch 32/80
249/249 [==============================] - 19s 75ms/step - loss: 0.7958 - acc: 0.8474 - val_loss: 1.8594 - val_acc: 0.1270
Epoch 33/80
249/249 [==============================] - 19s 75ms/step - loss: 0.7452 - acc: 0.8795 - val_loss: 1.8260 - val_acc: 0.1587
Epoch 34/80
249/249 [==============================] - 19s 75ms/step - loss: 0.7395 - acc: 0.8916 - val_loss: 1.8191 - val_acc: 0.1587
Epoch 35/80
249/249 [==============================] - 19s 75ms/step - loss: 0.6794 - acc: 0.9357 - val_loss: 1.8344 - val_acc: 0.1429
Epoch 36/80
249/249 [==============================] - 19s 75ms/step - loss: 0.6106 - acc: 0.9357 - val_loss: 1.7903 - val_acc: 0.1111
Epoch 37/80
249/249 [==============================] - 19s 75ms/step - loss: 0.5609 - acc: 0.9598 - val_loss: 1.7882 - val_acc: 0.1429
Epoch 38/80
249/249 [==============================] - 19s 75ms/step - loss: 0.5788 - acc: 0.9478 - val_loss: 1.8036 - val_acc: 0.1905
Epoch 39/80
249/249 [==============================] - 19s 75ms/step - loss: 0.5693 - acc: 0.9398 - val_loss: 1.7712 - val_acc: 0.1746
Epoch 40/80
249/249 [==============================] - 19s 75ms/step - loss: 0.4911 - acc: 0.9598 - val_loss: 1.8497 - val_acc: 0.1429
Epoch 41/80
249/249 [==============================] - 19s 75ms/step - loss: 0.4824 - acc: 0.9518 - val_loss: 1.8105 - val_acc: 0.1429
Epoch 42/80
249/249 [==============================] - 19s 75ms/step - loss: 0.4198 - acc: 0.9759 - val_loss: 1.8332 - val_acc: 0.1111
Epoch 43/80
249/249 [==============================] - 19s 75ms/step - loss: 0.3890 - acc: 0.9880 - val_loss: 1.9316 - val_acc: 0.1111
Epoch 44/80
249/249 [==============================] - 19s 75ms/step - loss: 0.3762 - acc: 0.9920 - val_loss: 1.8333 - val_acc: 0.1746
Epoch 45/80
249/249 [==============================] - 19s 75ms/step - loss: 0.3510 - acc: 0.9880 - val_loss: 1.8090 - val_acc: 0.1587
Epoch 46/80
249/249 [==============================] - 19s 75ms/step - loss: 0.3306 - acc: 0.9880 - val_loss: 1.8230 - val_acc: 0.1587
Epoch 47/80
249/249 [==============================] - 19s 75ms/step - loss: 0.2814 - acc: 1.0000 - val_loss: 1.7843 - val_acc: 0.2222
Epoch 48/80
249/249 [==============================] - 19s 75ms/step - loss: 0.2794 - acc: 1.0000 - val_loss: 1.8147 - val_acc: 0.2063
Epoch 49/80
249/249 [==============================] - 19s 75ms/step - loss: 0.2430 - acc: 1.0000 - val_loss: 1.8488 - val_acc: 0.1587
Epoch 50/80
249/249 [==============================] - 19s 75ms/step - loss: 0.2216 - acc: 1.0000 - val_loss: 1.8215 - val_acc: 0.1587

• Notice that while the validation accuracy isn't improving, the training accuracy has reached 100%, while the training loss keeps decreasing. This is a typical case of overfitting. One thing you could try is regularizing the model (e.g. through parameter norm penalties or dropout, etc.) You could also read this post where I elaborate a bit more on the problem you're facing. – Djib2011 Apr 20 '19 at 23:02
• "The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data." - John Tukey – Spacedman May 21 '19 at 13:48

Looking at your input, it seems that the labels are sorted in the dataset. So while calling the validation split function, you are training the model on (312*0.66) 206 training points belonging to the classes from probably from 0 to 3/4 and trying to validate on the class not present in the training dataset (class 5). This is the reason why your training accuracy is increasing but the validation accuracy isn't. You should turn the shuffle=True and train again.