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[MINOR][DOC] Correct code snippet results in quick start documentation

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## What changes were proposed in this pull request?

As README.md file is updated over time. Some code snippet outputs are not correct based on new README.md file. For example:
```
scala> textFile.count()
res0: Long = 126
```
should be
```
scala> textFile.count()
res0: Long = 99
```
This pr is to add comments to point out this problem so that new spark learners have a correct reference.
Also, fixed a samll bug, inside current documentation, the outputs of linesWithSpark.count() without and with cache are different (one is 15 and the other is 19)
```
scala> val linesWithSpark = textFile.filter(line => line.contains("Spark"))
linesWithSpark: org.apache.spark.rdd.RDD[String] = MapPartitionsRDD[2] at filter at <console>:27

scala> textFile.filter(line => line.contains("Spark")).count() // How many lines contain "Spark"?
res3: Long = 15

...

scala> linesWithSpark.cache()
res7: linesWithSpark.type = MapPartitionsRDD[2] at filter at <console>:27

scala> linesWithSpark.count()
res8: Long = 19
```

## How was this patch tested?

manual test:  run `$ SKIP_API=1 jekyll serve --watch`

Author: linbojin <linbojin203@gmail.com>

Closes #14645 from linbojin/quick-start-documentation.
This commit is contained in:
linbojin 2016-08-16 11:37:54 +01:00 committed by Sean Owen
parent 8fdc6ce400
commit 6f0988b129
1 changed files with 5 additions and 5 deletions
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10
docs/quick-start.md
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@ -40,7 +40,7 @@ RDDs have _[actions](programming-guide.html#actions)_, which return values, and
{% highlight scala %}
scala> textFile.count() // Number of items in this RDD
res0: Long = 126
res0: Long = 126 // May be different from yours as README.md will change over time, similar to other outputs
scala> textFile.first() // First item in this RDD
res1: String = # Apache Spark
@ -184,10 +184,10 @@ scala> linesWithSpark.cache()
res7: linesWithSpark.type = MapPartitionsRDD[2] at filter at <console>:27
scala> linesWithSpark.count()
res8: Long = 19
res8: Long = 15
scala> linesWithSpark.count()
res9: Long = 19
res9: Long = 15
{% endhighlight %}
It may seem silly to use Spark to explore and cache a 100-line text file. The interesting part is
@ -202,10 +202,10 @@ a cluster, as described in the [programming guide](programming-guide.html#initia
>>> linesWithSpark.cache()
>>> linesWithSpark.count()
19
15
>>> linesWithSpark.count()
19
15
{% endhighlight %}
It may seem silly to use Spark to explore and cache a 100-line text file. The interesting part is