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Ray Serve is a simple high-throughput model serving library that can wrap around your ML model.

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Simple Example of Logistic Regression

In this example, we train an external scikit-learn model to use for making predictions.

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Creating the Ray Serve Model

Let’s look at an actual model wrapped by a class that complies with the requirements. 
import ray
from fastapi import Request, FastAPI
from ray import serve
import time
import pandas as pd
import json

app = FastAPI()

async def parse_req(request: Request):
    data = await request.json()
    target = data.get('target', None)
    di = json.loads(data['df'])
    df = pd.DataFrame(di)
    return df, target


@serve.deployment(route_prefix="/my_model")
@serve.ingress(app)
class MyModel:
    @app.post("/train")
    async def train(self, request: Request):
        df, target = await parse_req(request)
        feature_cols = list(set(list(df.columns)) - set([target]))
        self.feature_cols = feature_cols
        X = df.loc[:, self.feature_cols]
        Y = list(df[target])
        self.model = LogisticRegression()
        self.model.fit(X, Y)
        return {'status': 'ok'}

    @app.post("/predict")
    async def predict(self, request: Request):
        df, _ = await parse_req(request)
        X = df.loc[:, self.feature_cols]
        predictions = self.model.predict(X)
        index = list(range(len(predictions)))
        pred_dict = {'prediction': [float(x) for x in predictions], 'index': index}
        return pred_dict

my_app = MyModel.bind()
After saving the above code into rayserve.py, run it using serve run rayserve:my_app. It is important to have the /train and /predict endpoints. The /train endpoint accepts two parameters to be sent via POST:
  • df is a serialized dictionary that can be converted into a pandas dataframe.
  • target is the name of the target column to be predicted.
It returns a JSON object containing the status key and the ok value. The /predict endpoint requires one parameter to be sent via POST:
  • df is a serialized dictionary that can be converted into a pandas dataframe.
It returns a dictionary containing the prediction and index keys. It stores the predictions. Additional keys can be returned for confidence and confidence intervals.

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Bringing the Ray Serve Model to MindsDB

Once you start the RayServe-wrapped model, you can create and train it in MindsDB. 
CREATE MODEL mindsdb.byom_ray_serve
FROM mydb (
    SELECT number_of_rooms, initial_price, rental_price
    FROM test_data.home_rentals
)
PREDICT number_of_rooms
USING
    url.train = 'http://127.0.0.1:8000/my_model/train',
    url.predict = 'http://127.0.0.1:8000/my_model/predict',
    dtype_dict={"number_of_rooms": "categorical", "initial_price": "integer", "rental_price": "integer"},
    format='ray_server';
Now, you can fetch predictions using the standard MindsDB syntax. Follow the guide on the SELECT statement to learn more. You can directly pass input data in the WHERE clause to get a single prediction. 
SELECT *
FROM byom_ray_serve
WHERE initial_price=3000
AND rental_price=3000;
Or you can JOIN the model wth a data table to get bulk predictions. 
SELECT tb.number_of_rooms, t.rental_price, tb.index
FROM mydb.test_data.home_rentals AS t
JOIN mindsdb.byom_ray_serve AS tb
WHERE t.rental_price > 5300;
Limit for POST RequestsPlease note that if your model is behind a reverse proxy like nginx, you might have to increase the maximum limit for POST requests in order to receive the training data. MindsDB can send as much as you’d like - it has been stress-tested with over a billion rows.

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Example of Keras NLP Model

Here, we consider a natural language processing (NLP) task where we want to train a neural network using Keras to detect if a tweet is related to a natural disaster, such as fires, earthquakes, etc. Please download this dataset to follow the example.

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Creating the Ray Serve Model

We create a Ray Serve service that wraps around the Kaggle NLP Model that can be trained and used for making predictions. 
import re
import time
import json
import string
import requests
from collections import Counter, defaultdict

import ray
from ray import serve

import gensim
import numpy as np
import pandas as pd
from tqdm import tqdm
from nltk.util import ngrams
from nltk.corpus import stopwords
from nltk.tokenize import word_tokenize
from fastapi import Request, FastAPI
from sklearn.model_selection import train_test_split
from sklearn.feature_extraction.text import CountVectorizer

from tensorflow.keras.preprocessing.text import Tokenizer
from tensorflow.keras.preprocessing.sequence import pad_sequences
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Embedding, LSTM, Dense, SpatialDropout1D
from tensorflow.keras.initializers import Constant
from tensorflow.keras.optimizers import Adam

app = FastAPI()
stop = set(stopwords.words('english'))


async def parse_req(request: Request):
    data = await request.json()
    target = data.get('target', None)
    di = json.loads(data['df'])
    df = pd.DataFrame(di)
    return df, target


@serve.deployment(route_prefix="/nlp_kaggle_model")
@serve.ingress(app)
class Model:
    MAX_LEN = 100
    GLOVE_DIM = 50
    EPOCHS = 10

    def __init__(self):
        self.model = None

    @app.post("/train")
    async def train(self, request: Request):
        df, target = await parse_req(request)

        target_arr = df.pop(target).values
        df = self.preprocess_df(df)
        train_corpus = self.create_corpus(df)

        self.embedding_dict = {}
        with open('./glove.6B.50d.txt', 'r') as f:
            for line in f:
                values = line.split()
                word = values[0]
                vectors = np.asarray(values[1:], 'float32')
                self.embedding_dict[word] = vectors
        f.close()

        self.tokenizer_obj = Tokenizer()
        self.tokenizer_obj.fit_on_texts(train_corpus)

        sequences = self.tokenizer_obj.texts_to_sequences(train_corpus)
        tweet_pad = pad_sequences(sequences, maxlen=self.__class__.MAX_LEN, truncating='post', padding='post')
        df = tweet_pad[:df.shape[0]]

        word_index = self.tokenizer_obj.word_index
        num_words = len(word_index) + 1
        embedding_matrix = np.zeros((num_words, self.__class__.GLOVE_DIM))

        for word, i in tqdm(word_index.items()):
            if i > num_words:
                continue

            emb_vec = self.embedding_dict.get(word)
            if emb_vec is not None:
                embedding_matrix[i] = emb_vec

        self.model = Sequential()
        embedding = Embedding(num_words,
                              self.__class__.GLOVE_DIM,
                              embeddings_initializer=Constant(embedding_matrix),
                              input_length=self.__class__.MAX_LEN,
                              trainable=False)
        self.model.add(embedding)
        self.model.add(SpatialDropout1D(0.2))
        self.model.add(LSTM(64, dropout=0.2, recurrent_dropout=0.2))
        self.model.add(Dense(1, activation='sigmoid'))

        optimizer = Adam(learning_rate=1e-5)
        self.model.compile(loss='binary_crossentropy', optimizer=optimizer, metrics=['accuracy'])

        X_train, X_test, y_train, y_test = train_test_split(df, target_arr, test_size=0.15)
        self.model.fit(X_train, y_train, batch_size=4, epochs=self.__class__.EPOCHS, validation_data=(X_test, y_test), verbose=2)

        return {'status': 'ok'}

    @app.post("/predict")
    async def predict(self, request: Request):
        df, _ = await parse_req(request)

        df = self.preprocess_df(df)
        test_corpus = self.create_corpus(df)

        sequences = self.tokenizer_obj.texts_to_sequences(test_corpus)
        tweet_pad = pad_sequences(sequences, maxlen=self.__class__.MAX_LEN, truncating='post', padding='post')
        df = tweet_pad[:df.shape[0]]

        y_pre = self.model.predict(df)
        y_pre = np.round(y_pre).astype(int).flatten().tolist()
        sub = pd.DataFrame({'target': y_pre})

        pred_dict = {'prediction': [float(x) for x in sub['target'].values]}
        return pred_dict

    def preprocess_df(self, df):
        df = df[['text']]
        df['text'] = df['text'].apply(lambda x: self.remove_URL(x))
        df['text'] = df['text'].apply(lambda x: self.remove_html(x))
        df['text'] = df['text'].apply(lambda x: self.remove_emoji(x))
        df['text'] = df['text'].apply(lambda x: self.remove_punct(x))
        return df

    def remove_URL(self, text):
        url = re.compile(r'https?://\S+|www\.\S+')
        return url.sub(r'', text)

    def remove_html(self, text):
        html = re.compile(r'<.*?>')
        return html.sub(r'', text)

    def remove_punct(self, text):
        table = str.maketrans('', '', string.punctuation)
        return text.translate(table)

    def remove_emoji(self, text):
        emoji_pattern = re.compile("["
                                   u"\U0001F600-\U0001F64F"  # emoticons
                                   u"\U0001F300-\U0001F5FF"  # symbols & pictographs
                                   u"\U0001F680-\U0001F6FF"  # transport & map symbols
                                   u"\U0001F1E0-\U0001F1FF"  # flags (iOS)
                                   u"\U00002702-\U000027B0"
                                   u"\U000024C2-\U0001F251"
                                   "]+", flags=re.UNICODE)
        return emoji_pattern.sub(r'', text)

    def create_corpus(self, df):
        corpus = []
        for tweet in tqdm(df['text']):
            words = [word.lower() for word in word_tokenize(tweet) if ((word.isalpha() == 1) & (word not in stop))]
            corpus.append(words)
        return corpus


if __name__ == '__main__':

    ray.init()
    serve.start(detached=True)

    Model.deploy()

    while True:
        time.sleep(1)
Now, we need access to the training data. For that, we create a table called nlp_kaggle_train to load the dataset that the original model uses. The nlp_kaggle_train table contains the following columns: 
id INT,
keyword VARCHAR(255),
location VARCHAR(255),
text VARCHAR(5000),
target INT
Please note that the specifics of the schema/table and how to ingest the CSV data vary depending on your database.

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Bringing the Ray Serve Model to MindsDB

Now, we can create and train this custom model in MindsDB. 
CREATE MODEL mindsdb.byom_ray_serve_nlp
FROM maria (
    SELECT text, target
    FROM test.nlp_kaggle_train
) PREDICT target
USING
    url.train = 'http://127.0.0.1:8000/nlp_kaggle_model/train',
    url.predict = 'http://127.0.0.1:8000/nlp_kaggle_model/predict',
    dtype_dict={"text": "rich_text", "target": "integer"},
    format='ray_server';
The training process takes some time, considering that this model is a neural network rather than a simple logistic regression. You can check the model status using this query: 
DESCRIBE byom_ray_serve_nlp;
Once the status of the predictor has a value of trained, you can fetch predictions using the standard MindsDB syntax. Follow the guide on the SELECT statement to learn more. 
SELECT *
FROM mindsdb.byom_ray_serve_nlp
WHERE text='The tsunami is coming, seek high ground';
The expected output of the query above is 1. 
SELECT *
FROM mindsdb.byom_ray_serve_nlp
WHERE text='This is lovely dear friend';
The expected output of the query above is 0.
Wrong Results?If your results do not match this example, try training the model for a longer amount of epochs.
Get More InsightsCheck out the article on How to bring your own machine learning model to databases by Patricio Cerda Mardini to learn more.
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