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Use HDInsight Spark cluster to analyze data in Data Lake Storage Gen1

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  • 4 minutes to read

In this article, you use Jupyter Notebook available with HDInsight Spark clusters to run a job that reads data from a Data Lake Storage account.

Prerequisites

Prepare the data

Note

You do not need to perform this step if you have created the HDInsight cluster with Data Lake Storage as default storage. The cluster creation process adds some sample data in the Data Lake Storage account that you specify while creating the cluster. Skip to the section Use HDInsight Spark cluster with Data Lake Storage.

If you created an HDInsight cluster with Data Lake Storage as additional storage and Azure Storage Blob as default storage, you should first copy over some sample data to the Data Lake Storage account. You can use the sample data from the Azure Storage Blob associated with the HDInsight cluster. You can use the ADLCopy tool to do so. Download and install the tool from the link.

  1. Open a command prompt and navigate to the directory where AdlCopy is installed, typically %HOMEPATH%\Documents\adlcopy.

  2. Run the following command to copy a specific blob from the source container to Data Lake Storage:

    AdlCopy /source https://<source_account>.blob.core.windows.net/<source_container>/<blob name> /dest swebhdfs://<dest_adls_account>.azuredatalakestore.net/<dest_folder>/ /sourcekey <storage_account_key_for_storage_container>

    Copy the HVAC.csv sample data file at /HdiSamples/HdiSamples/SensorSampleData/hvac/ to the Azure Data Lake Storage account. The code snippet should look like:

    AdlCopy /Source https://mydatastore.blob.core.windows.net/mysparkcluster/HdiSamples/HdiSamples/SensorSampleData/hvac/HVAC.csv /dest swebhdfs://mydatalakestore.azuredatalakestore.net/hvac/ /sourcekey uJUfvD6cEvhfLoBae2yyQf8t9/BpbWZ4XoYj4kAS5Jf40pZaMNf0q6a8yqTxktwVgRED4vPHeh/50iS9atS5LQ==

    Warning

    Make sure that the file and path names use the proper capitalization.

  3. You are prompted to enter the credentials for the Azure subscription under which you have your Data Lake Storage account. You see an output similar to the following snippet:

    Initializing Copy.
Copy Started.
100% data copied.
Copy Completed. 1 file copied.

    The data file (HVAC.csv) will be copied under a folder /hvac in the Data Lake Storage account.

Use an HDInsight Spark cluster with Data Lake Storage Gen1

  1. From the Azure portal, from the startboard, click the tile for your Apache Spark cluster (if you pinned it to the startboard). You can also navigate to your cluster under Browse All > HDInsight Clusters.

  2. From the Spark cluster blade, click Quick Links, and then from the Cluster Dashboard blade, click Jupyter Notebook. If prompted, enter the admin credentials for the cluster.

    Note

    You may also reach the Jupyter Notebook for your cluster by opening the following URL in your browser. Replace CLUSTERNAME with the name of your cluster:

    https://CLUSTERNAME.azurehdinsight.net/jupyter

  3. Create a new notebook. Click New, and then click PySpark.

    Create a new Jupyter Notebook

  4. Because you created a notebook using the PySpark kernel, you do not need to create any contexts explicitly. The Spark and Hive contexts will be automatically created for you when you run the first code cell. You can start by importing the types required for this scenario. To do so, paste the following code snippet in a cell and press SHIFT + ENTER.

    from pyspark.sql.types import *

    Every time you run a job in Jupyter, your web browser window title will show a (Busy) status along with the notebook title. You will also see a solid circle next to the PySpark text in the top-right corner. After the job is completed, this will change to a hollow circle.

    Status of a Jupyter Notebook job

  5. Load sample data into a temporary table using the HVAC.csv file you copied to the Data Lake Storage Gen1 account. You can access the data in the Data Lake Storage account using the following URL pattern.

    • If you have Data Lake Storage Gen1 as default storage, HVAC.csv will be at the path similar to the following URL:

      adl://<data_lake_store_name>.azuredatalakestore.net/<cluster_root>/HdiSamples/HdiSamples/SensorSampleData/hvac/HVAC.csv

      Or, you could also use a shortened format such as the following:

      adl:///HdiSamples/HdiSamples/SensorSampleData/hvac/HVAC.csv

    • If you have Data Lake Storage as additional storage, HVAC.csv will be at the location where you copied it, such as:

      adl://<data_lake_store_name>.azuredatalakestore.net/<path_to_file>

      In an empty cell, paste the following code example, replace MYDATALAKESTORE with your Data Lake Storage account name, and press SHIFT + ENTER. This code example registers the data into a temporary table called hvac.

      # Load the data. The path below assumes Data Lake Storage is   default storage for the Spark cluster
hvacText = sc.textFile("adl://MYDATALAKESTORazuredatalakestore.  net/cluster/mysparkclusteHdiSamples/HdiSamples/  SensorSampleData/hvac/HVAC.csv")

# Create the schema
hvacSchema = StructType([StructField("date", StringTy(), False)  ,StructField("time", StringType(), FalseStructField  ("targettemp", IntegerType(), FalseStructField("actualtemp",   IntegerType(), FalseStructField("buildingID", StringType(),   False)])

# Parse the data in hvacText
hvac = hvacText.map(lambda s: s.split(",")).filt(lambda s: s  [0] != "Date").map(lambda s:(str(s[0]), s(s[1]), int(s[2]), int  (s[3]), str(s[6]) ))

# Create a data frame
hvacdf = sqlContext.createDataFrame(hvac,hvacSchema)

# Register the data fram as a table to run queries against
hvacdf.registerTempTable("hvac")

  6. Because you are using a PySpark kernel, you can now directly run a SQL query on the temporary table hvac that you just created by using the %%sql magic. For more information about the %%sql magic, as well as other magics available with the PySpark kernel, see Kernels available on Jupyter Notebooks with Apache Spark HDInsight clusters.

    %%sql
 SELECT buildingID, (targettemp - actualtemp) AS temp_diff, date FROM hvac WHERE date = \"6/1/13\"

  7. Once the job is completed successfully, the following tabular output is displayed by default.

    Table output of query result

    You can also see the results in other visualizations as well. For example, an area graph for the same output would look like the following.

    Area graph of query result

  8. After you have finished running the application, you should shutdown the notebook to release the resources. To do so, from the File menu on the notebook, click Close and Halt. This will shutdown and close the notebook.

Next steps