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Version: 0.11.3

Cognitive Services Advanced Guide: Asynchrony, Batching, Multi-Key

Step 1: Imports and Keys​

from synapse.ml.core.platform import find_secret

service_key = find_secret("cognitive-api-key")
service_loc = "eastus"

Step 2: Basic Usage​

Image 1Image 2Image 3
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from synapse.ml.cognitive.vision import AnalyzeImage

# Create a dataframe with the image URLs
base_url = "https://raw.githubusercontent.com/Azure-Samples/cognitive-services-sample-data-files/master/ComputerVision/Images/"
image_df = spark.createDataFrame(
    [(base_url + "objects.jpg",), (base_url + "dog.jpg",), (base_url + "house.jpg",)],
    ["image"],
)

# Run the Computer Vision service. Analyze Image extracts infortmation from/about the images.
analyzer = (
    AnalyzeImage()
    .setLocation(service_loc)
    .setSubscriptionKey(service_key)
    .setVisualFeatures(
        ["Categories", "Color", "Description", "Faces", "Objects", "Tags"]
    )
    .setOutputCol("analysis_results")
    .setImageUrlCol("image")
    .setErrorCol("error")
)

image_results = analyzer.transform(image_df).cache()

First we'll look at the full response objects:​

display(image_results)

We can select out just what we need:​

display(image_results.select("analysis_results.description.captions.text"))

What's going on under the hood​

When we call the cognitive service transformer, we start cognitive service clients on each of your spark workers. These clients send requests to the cloud, and turn the JSON responses into Spark Struct Types so that you can access any field that the service returns.

Step 3: Asynchronous Usage​

Apache Spark ordinarily parallelizes a computation to all of it's worker threads. When working with services however this parallelism doesent fully maximize throughput because workers sit idle as requests are processed on the server. The concurrency parameter makes sure that each worker can stay busy as they wait for requests to complete.

display(analyzer.setConcurrency(3).transform(image_df))

Faster without extra hardware:​

Step 4: Batching​

from synapse.ml.cognitive.text import TextSentiment

# Create a dataframe
text_df = spark.createDataFrame(
    [
        ("I am so happy today, its sunny!",),
        ("I am frustrated by this rush hour traffic",),
        ("The cognitive services on spark is pretty lit",),
    ],
    ["text"],
)

sentiment = (
    TextSentiment()
    .setTextCol("text")
    .setLocation(service_loc)
    .setSubscriptionKey(service_key)
    .setOutputCol("sentiment")
    .setErrorCol("error")
    .setBatchSize(10)
)

# Show the results of your text query
display(sentiment.transform(text_df).select("text", "sentiment.document.sentiment"))

Step 5: Multi-Key​

from synapse.ml.cognitive.text import TextSentiment
from pyspark.sql.functions import udf
import random

service_key_2 = find_secret("cognitive-api-key-2")
keys = [service_key, service_key_2]


@udf
def random_key():
    return keys[random.randint(0, len(keys) - 1)]


image_df2 = image_df.withColumn("key", random_key())

results = analyzer.setSubscriptionKeyCol("key").transform(image_df2)
display(results.select("key", "analysis_results.description.captions.text"))

Learn More​