Data sources
In this section, we introduce how to use data source in ML to load data. Besides some general data sources such as Parquet, CSV, JSON and JDBC, we also provide some specific data sources for ML.
Table of Contents
Image data source
This image data source is used to load image files from a directory, it can load compressed image (jpeg, png, etc.) into raw image representation via ImageIO
in Java library.
The loaded DataFrame has one StructType
column: “image”, containing image data stored as image schema.
The schema of the image
column is:
- origin:
StringType
(represents the file path of the image) - height:
IntegerType
(height of the image) - width:
IntegerType
(width of the image) - nChannels:
IntegerType
(number of image channels) - mode:
IntegerType
(OpenCV-compatible type) - data:
BinaryType
(Image bytes in OpenCV-compatible order: row-wise BGR in most cases)
In PySpark we provide Spark SQL data source API for loading image data as a DataFrame.
>>> df = spark.read.format("image").option("dropInvalid", True).load("data/mllib/images/origin/kittens")
>>> df.select("image.origin", "image.width", "image.height").show(truncate=False)
+-----------------------------------------------------------------------+-----+------+
|origin |width|height|
+-----------------------------------------------------------------------+-----+------+
|file:///spark/data/mllib/images/origin/kittens/54893.jpg |300 |311 |
|file:///spark/data/mllib/images/origin/kittens/DP802813.jpg |199 |313 |
|file:///spark/data/mllib/images/origin/kittens/29.5.a_b_EGDP022204.jpg |300 |200 |
|file:///spark/data/mllib/images/origin/kittens/DP153539.jpg |300 |296 |
+-----------------------------------------------------------------------+-----+------+
ImageDataSource
implements a Spark SQL data source API for loading image data as a DataFrame.
scala> val df = spark.read.format("image").option("dropInvalid", true).load("data/mllib/images/origin/kittens")
df: org.apache.spark.sql.DataFrame = [image: struct<origin: string, height: int ... 4 more fields>]
scala> df.select("image.origin", "image.width", "image.height").show(truncate=false)
+-----------------------------------------------------------------------+-----+------+
|origin |width|height|
+-----------------------------------------------------------------------+-----+------+
|file:///spark/data/mllib/images/origin/kittens/54893.jpg |300 |311 |
|file:///spark/data/mllib/images/origin/kittens/DP802813.jpg |199 |313 |
|file:///spark/data/mllib/images/origin/kittens/29.5.a_b_EGDP022204.jpg |300 |200 |
|file:///spark/data/mllib/images/origin/kittens/DP153539.jpg |300 |296 |
+-----------------------------------------------------------------------+-----+------+
ImageDataSource
implements Spark SQL data source API for loading image data as a DataFrame.
Dataset<Row> imagesDF = spark.read().format("image").option("dropInvalid", true).load("data/mllib/images/origin/kittens");
imageDF.select("image.origin", "image.width", "image.height").show(false);
/*
Will output:
+-----------------------------------------------------------------------+-----+------+
|origin |width|height|
+-----------------------------------------------------------------------+-----+------+
|file:///spark/data/mllib/images/origin/kittens/54893.jpg |300 |311 |
|file:///spark/data/mllib/images/origin/kittens/DP802813.jpg |199 |313 |
|file:///spark/data/mllib/images/origin/kittens/29.5.a_b_EGDP022204.jpg |300 |200 |
|file:///spark/data/mllib/images/origin/kittens/DP153539.jpg |300 |296 |
+-----------------------------------------------------------------------+-----+------+
*/
In SparkR we provide Spark SQL data source API for loading image data as a DataFrame.
> df = read.df("data/mllib/images/origin/kittens", "image")
> head(select(df, df$image.origin, df$image.width, df$image.height))
1 file:///spark/data/mllib/images/origin/kittens/54893.jpg
2 file:///spark/data/mllib/images/origin/kittens/DP802813.jpg
3 file:///spark/data/mllib/images/origin/kittens/29.5.a_b_EGDP022204.jpg
4 file:///spark/data/mllib/images/origin/kittens/DP153539.jpg
width height
1 300 311
2 199 313
3 300 200
4 300 296
LIBSVM data source
This LIBSVM
data source is used to load ‘libsvm’ type files from a directory.
The loaded DataFrame has two columns: label containing labels stored as doubles and features containing feature vectors stored as Vectors.
The schemas of the columns are:
- label:
DoubleType
(represents the instance label) - features:
VectorUDT
(represents the feature vector)
In PySpark we provide Spark SQL data source API for loading LIBSVM
data as a DataFrame.
>>> df = spark.read.format("libsvm").option("numFeatures", "780").load("data/mllib/sample_libsvm_data.txt")
>>> df.show(10)
+-----+--------------------+
|label| features|
+-----+--------------------+
| 0.0|(780,[127,128,129...|
| 1.0|(780,[158,159,160...|
| 1.0|(780,[124,125,126...|
| 1.0|(780,[152,153,154...|
| 1.0|(780,[151,152,153...|
| 0.0|(780,[129,130,131...|
| 1.0|(780,[158,159,160...|
| 1.0|(780,[99,100,101,...|
| 0.0|(780,[154,155,156...|
| 0.0|(780,[127,128,129...|
+-----+--------------------+
only showing top 10 rows
LibSVMDataSource
implements a Spark SQL data source API for loading LIBSVM
data as a DataFrame.
scala> val df = spark.read.format("libsvm").option("numFeatures", "780").load("data/mllib/sample_libsvm_data.txt")
df: org.apache.spark.sql.DataFrame = [label: double, features: vector]
scala> df.show(10)
+-----+--------------------+
|label| features|
+-----+--------------------+
| 0.0|(780,[127,128,129...|
| 1.0|(780,[158,159,160...|
| 1.0|(780,[124,125,126...|
| 1.0|(780,[152,153,154...|
| 1.0|(780,[151,152,153...|
| 0.0|(780,[129,130,131...|
| 1.0|(780,[158,159,160...|
| 1.0|(780,[99,100,101,...|
| 0.0|(780,[154,155,156...|
| 0.0|(780,[127,128,129...|
+-----+--------------------+
only showing top 10 rows
LibSVMDataSource
implements Spark SQL data source API for loading LIBSVM
data as a DataFrame.
Dataset<Row> df = spark.read.format("libsvm").option("numFeatures", "780").load("data/mllib/sample_libsvm_data.txt");
df.show(10);
/*
Will output:
+-----+--------------------+
|label| features|
+-----+--------------------+
| 0.0|(780,[127,128,129...|
| 1.0|(780,[158,159,160...|
| 1.0|(780,[124,125,126...|
| 1.0|(780,[152,153,154...|
| 1.0|(780,[151,152,153...|
| 0.0|(780,[129,130,131...|
| 1.0|(780,[158,159,160...|
| 1.0|(780,[99,100,101,...|
| 0.0|(780,[154,155,156...|
| 0.0|(780,[127,128,129...|
+-----+--------------------+
only showing top 10 rows
*/
In SparkR we provide Spark SQL data source API for loading LIBSVM
data as a DataFrame.
> df = read.df("data/mllib/sample_libsvm_data.txt", "libsvm")
> head(select(df, df$label, df$features), 10)
label features
1 0 <environment: 0x7fe6d35366e8>
2 1 <environment: 0x7fe6d353bf78>
3 1 <environment: 0x7fe6d3541840>
4 1 <environment: 0x7fe6d3545108>
5 1 <environment: 0x7fe6d354c8e0>
6 0 <environment: 0x7fe6d35501a8>
7 1 <environment: 0x7fe6d3555a70>
8 1 <environment: 0x7fe6d3559338>
9 0 <environment: 0x7fe6d355cc00>
10 0 <environment: 0x7fe6d35643d8>