Github user liancheng commented on a diff in the pull request:
https://github.com/apache/spark/pull/14368#discussion_r72387754
--- Diff: examples/src/main/r/RSparkSQLExample.R ---
@@ -18,31 +18,43 @@
library(SparkR)
# $example on:init_session$
-sparkR.session(appName = "MyApp", sparkConfig = list(spark.executor.memory
= "1g"))
+sparkR.session(appName = "MyApp", sparkConfig =
list(spark.some.config.option = "some-value"))
# $example off:init_session$
-# $example on:create_DataFrames$
+# $example on:create_df$
df <- read.json("examples/src/main/resources/people.json")
# Displays the content of the DataFrame
head(df)
+## age name
+## 1 NA Michael
+## 2 30 Andy
+## 3 19 Justin
# Another method to print the first few rows and optionally truncate the
printing of long values
showDF(df)
-# $example off:create_DataFrames$
+## +----+-------+
+## | age| name|
+## +----+-------+
+## |null|Michael|
--- End diff --
I'm not familiar with SparkR, so please correct me if I'm wrong. IIRC,
`showDF` is mapped to the Scala method `Dataset.show()`, which executes in the
JVM, where `NA` isn't available, and we have to use `null` as the only
reasonable alternative. You may see that the previous `head(df)` call does
print `NA` instead of `null`.
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