/cleansed_emocontext

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Cleansed_EmoContext


EmoContext - Task Report

I've noticed that quite a few people have starred or forked this repository. I dont' remember much of the work I had done for this, but I do remember that everything I had messed around after december 13th more or less ended up worsening performance. If you are interested in what I have done here it might be best if you go through the commit history and find a version around December 2018 and work from there.

Table of Contents

Introduction

When you read, "Why don't you ever text me", does it conveys an angry emotion or sad emotion?

Understanding Emotions in Textual Conversations is a hard problem in absence of voice modulations and facial expressions. The shared task, "EmoContext" is designed to invite research in this area.

Description

In this task, you are given a textual dialogue i.e. a user utterance along with two turns of context, you have to classify the emotion of user utterance as one of the emotion classes: happy, sad, angry or others. ​

Data

The training data set contains 15K records for emotion classes i.e., happy, sad, and angry combined. It also contains 15K records not belonging to any of the aforementioned emotion classes. For Test Data, 2703 records of unlabelled data is provided to be used to evaluate models we create. Final testing would be done on as of yet unreleased data.

Examples from the dataset -

turn1 turn2 turn3 label
Don't worry I'm girl hmm how do I know if you are What's ur name? others
When did I? saw many times i think -_- No. I never saw you angry
Money money and lots of money😍😍 I need to get it tailored but I'm in love with it 😍 😁😁 happy
Bcoz u dont know wat is to miss someone but sometimes one can't express the same 😒 sad

Each turn here represents a text message in a conversation between two parties. Note that turn1 and turn3 are texts sent by an anonymous person, while turn2 is a text reply sent by Ruuh, a AI-based chatbot.

It is important to note that the task requires us to predict the emotion exhibited only in the last text message, turn3, and not the entire conversation. If the sender is angry in the first text message but calms down by the last text message the label prediction is not expected to be angry.

Methodology

The approach used was a standard one for these sort of short text classification tasks - pre-trained word vectors in conjunction with LSTMs - modified to fit the unique challenges in this task.

Final architecture of the Neural Network

Final architecture of the Neural Network

Justification

Pre-trained word embeddings + Bi-LSTMs are what is usually used in state of the art text classification systems, so it's choice doesn't need much justification.

3 different Bi-LSTMs were used for each turn as show in the above diagram, because I felt different representations are needed for each turn, especially considering that they are not equivalent. This hypothesis worked out well in practice, taking me from an F1 of 0.64 to 0.66 upon making the switch on the evaluation dataset.

Custom embeddings were trained and used because our corpus had a lot of textual (such as :(, :p, etc.) and unicode emojis (😍, 😁, etc.). FastText did not have good vectors for these - a nearest neighbour search for these words using the fasttext embeddings revealed that fasttext's representations for these words are mostly nonsensical.

Evaluation (as of 13th December, 2018. 12:30 pm)

I didn't write proper code to plot graphs for testing and training loss curves, and thusly made random guesses on how many epochs to run the network for. This almost certainly means that my network is either under-fitting or over-fitting, my guess would be over-fitting.

Regardless, training of the network wasn't done using best practices, something that I plan to correct in the near future. Even so, the best F1 score I received was 0.703108 which meant a rank of 44 on the leaderboard, of the total 241 participants.

That puts me at approximately the top-20th percentile (18.25%) in the competition. The live leaderboard can be found here.

A table of all of my submisions made to the server is shown below.

# SCORE FILENAME SUBMISSION DATE STATUS
1 --- test.zip 09/21/2018 02:23:57 Finished
2 --- test.zip 09/21/2018 02:23:57 Finished
3 0.359338 test.zip 09/21/2018 02:34:49 Finished
4 0.491269 test.zip 09/27/2018 18:25:19 Finished
5 0.54375 test.zip 09/27/2018 18:34:09 Finished
6 0.488522 test.zip 09/28/2018 02:36:23 Finished
7 0.488522 test.zip 09/28/2018 02:47:14 Finished
8 0.511581 test.zip 09/28/2018 02:59:29 Finished
9 0.525054 test.zip 09/28/2018 03:06:21 Finished
10 0.525054 test.zip 09/28/2018 03:06:22 Finished
11 0.525054 test.zip 09/28/2018 03:08:35 Finished
12 0.527421 test.zip 09/28/2018 03:10:09 Finished
13 0.517467 test.zip 09/28/2018 03:13:44 Finished
14 0.554278 test.zip 10/13/2018 19:02:52 Finished
15 0.554278 test.zip 10/13/2018 19:02:53 Finished
16 0.574772 test.zip 10/13/2018 20:07:57 Finished
17 --- test.zip 11/08/2018 17:18:47 Submitted
18 --- test.zip 11/08/2018 18:07:28 Running
19 --- test.zip 11/15/2018 15:27:47 Finished
20 0.439024 test.zip 11/15/2018 16:22:39 Finished
21 0.452756 test.zip 11/15/2018 16:48:59 Finished
22 0.541096 test.zip 11/17/2018 14:57:02 Finished
23 0.541096 test.zip 11/17/2018 19:39:13 Finished
24 0.471014 test.zip 11/17/2018 19:40:10 Finished
25 0.495238 test.zip 11/17/2018 19:56:02 Finished
26 0.472597 test.zip 11/17/2018 20:03:42 Finished
27 0.488593 test.zip 11/17/2018 20:14:58 Finished
28 0.573643 test.zip 11/25/2018 01:35:56 Finished
29 0.624481 test.zip 11/25/2018 01:55:35 Finished
30 0.572973 test.zip 11/25/2018 02:14:25 Finished
31 0.607109 test.zip 11/25/2018 02:48:27 Finished
32 0.604374 test.zip 11/25/2018 03:23:21 Finished
33 0.596899 test.zip 11/25/2018 03:43:54 Finished
34 0.5941 test.zip 11/25/2018 04:03:46 Finished
35 0.568841 test.zip 11/25/2018 04:19:53 Finished
36 0.578999 test.zip 11/25/2018 04:49:15 Finished
37 0.59434 test.zip 11/25/2018 05:08:22 Finished
38 0.622047 test.zip 11/25/2018 05:30:01 Finished
39 0.596262 test.zip 11/25/2018 06:03:08 Finished
40 0.619487 test.zip 11/25/2018 06:35:30 Finished
41 0.585782 test.zip 11/25/2018 17:51:26 Finished
42 0.619808 test.zip 11/25/2018 18:27:06 Finished
43 0.619958 test.zip 11/25/2018 22:39:42 Finished
44 0.664688 test.zip 11/25/2018 23:05:23 Finished
45 0.670577 test.zip 11/25/2018 23:23:08 Finished
46 0.667333 test.zip 11/26/2018 00:37:52 Finished
47 0.66997 test.zip 11/26/2018 01:07:52 Finished
48 0.672878 test.zip 11/26/2018 02:21:29 Finished
49 0.664024 test.zip 11/26/2018 02:44:03 Finished
50 0.694268 test.zip 11/26/2018 03:15:21 Finished
51 0.64813 test.zip 11/26/2018 03:55:27 Finished
52 0.647564 test.zip 11/26/2018 04:34:42 Finished
53 0.668016 test.zip 11/26/2018 05:07:59 Finished
54 0.658359 test.zip 11/26/2018 15:05:05 Finished
55 0.665335 test.zip 11/26/2018 16:33:20 Finished
56 0.672619 test.zip 11/26/2018 21:37:31 Finished
57 0.703108 test.zip 11/26/2018 22:11:04 Finished
58 0.675877 test.zip 11/26/2018 22:46:43 Finished
59 0.690155 test.zip 11/26/2018 23:29:15 Finished
60 0.674822 test.zip 11/27/2018 01:19:46 Finished
61 0.69239 test.zip 11/27/2018 01:56:31 Finished
62 0.680585 test.zip 11/27/2018 16:14:26 Finished
63 0.664039 test.zip 11/27/2018 17:03:21 Finished
64 0.688797 test.zip 11/27/2018 17:35:20 Finished
65 0.670695 test.zip 11/27/2018 18:01:05 Finished
66 0.666667 test.zip 11/27/2018 19:47:04 Finished
67 0.676768 test.zip 11/27/2018 20:24:30 Finished
68 0.67019 test.zip 11/27/2018 23:51:44 Finished
69 0.695652 test.zip 11/28/2018 02:59:22 Finished
70 0.678173 test.zip 11/28/2018 03:41:32 Finished
71 0.685773 test.zip 11/28/2018 04:44:13 Finished
72 0.660194 test.zip 11/28/2018 05:13:12 Finished
73 0.67686 test.zip 11/28/2018 10:49:08 Finished
74 0.697725 test.zip 11/28/2018 14:30:33 Finished
75 0.674067 test.zip 11/28/2018 15:58:40 Finished
76 0.690476 test.zip 11/28/2018 17:13:31 Finished
77 0.67551 test.zip 11/28/2018 18:49:43 Finished
78 0.082073 test.zip 11/29/2018 14:12:09 Finished
79 0.6714 test.zip 11/29/2018 16:18:08 Finished
80 0.703108 test (5).zip 11/29/2018 16:19:06 Finished

Discussion and Future Plans

As noted earlier, I haven't been using the best practices while training my models, and that is the first thing I intend to fix.

Other possible improvements, in no particular order, are noted below -

  • One of the easiest things to do to improve model accuracy is to use a hierarchy of them in tandem. One model using the same architecture as above to predict whether the text messages fall into the others category or not, and another to decide whether the model fall into happy, sad, or angry category. The reasoning being the massive class imbalance that exists in the evaluation dataset - 96% of the records are of the others category, while only 4% are happy, sad, or angry.

It should also be noted that the final F1 score is calculated using only the precision and recall of the happy, sad, and angry categories and the others category is ignored. Thusly, implementing a hierarchy might get surprising improvements in the final score.

  • I haven't done this yet because the idea was to find the best performing combination of a Neural Network architecture, Word Embeddings, and pre-processing. After the best model I can make is found, then I'll proceed to implement an hierarchy of classifiers to improve accuracy.
  • Another obvious thing to do is to do an train multiple models with different combinations of embeddings, architecture, and pre-processing and then use all of them in an ensemble. Training multiple versions of the same model is also a thing to try out, since it's possible they would converge onto a different set of weights each time, especially if we vary the training hyper-parameters. From what I've been reading, the more models you have, the better.
  • Something that seems to have worked already is adding another Bi-LSTM layer between the embeddings and stack layers, and introducing a residual connection between them. This has led to remarkably faster convergence, and a higher overall accuracy during training, but hasn't been able to beat my best F1 on the evaluation dataset, most likely due to over-fitting. It seems promising though. I need to implement a better training strategy.

Text Data Augmentation

Something I am particularly excited to try out is Data Augmentation. Data augmentation is something that is frequently done in Computer Vision and image classification, and it has proven to be quite effective.

I haven't been able to find many instances of data augmentation being performed on text data, meaning maybe it isn't as useful as I am hoping for it to be. Things I've seen people discuss on the internet are -

  • Replacing words with their synonym.
  • Shuffling the order of sentences or paragraphs in large texts.
  • Using machine translation to go from English -> [Intermediary Language] -> English, effectively paraphrasing the data, if all goes well.

I do not like the idea of shuffling sentences or words, but the rest seem interesting enough to try. I also have a few ideas of my own, which I think I won't put into words until I've had a chance to try them out. I did tell you about them in class though, if you remember.

Data Provided by Microsoft.