November 2021
Intermediate to advanced
340 pages
10h 46m
Chinese
Content preview from Spark快速大数据分析（第2版）
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96
｜
第
4
章
// Scala代码
df.write.format("orc")
.mode("overwrite")
.option("compression", "snappy")
.save("/tmp/data/orc/df_orc")
# Python代码
(df.write.format("orc")
.mode("overwrite")
.option("compression", "snappy")
.save("/tmp/data/orc/flights_orc"))
以上代码会在指定路径下生成一个文件夹，其中包含一些经过压缩的
ORC
文件。
-rw-r--r-- 1 jules wheel 0 May 16 17:23 _SUCCESS
-rw-r--r-- 1 jules wheel 547 May 16 17:23 part-00000-<...>-c000.snappy.orc
4.3.8
图像
在
Spark 2.4
中，开发社区引入了图像文件这种新的数据源，以支持像
TensorFlow
和
PyTorch
这样的深度学习和机器学习框架。对于基于计算机视觉的机器学习应用，读取和处理图像数
据集至关重要。
将图像文件读入
DataFrame
和前面介绍的所有文件格式一样，可以使用
DataFrameReader
方法和选项来读取图像文件，
代码如下所示。
// Scala代码
import org.apache.spark.ml.source.image
val
imageDir ...
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