Add column to DataFrame in sparkR

Question

I would like to add a column filled with a character N in a DataFrame in SparkR. I would do it like that with non-SparkR code :

df$new_column <- "N"

But with SparkR, I get the following error :

Error: class(value) == "Column" || is.null(value) is not TRUE

I've tried insane things to manage it, I was able to create a column using another (existing) one with df <- withColumn(df, "new_column", df$existing_column), but this simple thing, nope...

Any help ?

Thanks.

Ellenaellender

The only hack I know for this is to use ifelse with the same return value for both conditions. So df$new <- ifelse(condition, 'N', 'N'). – Faliscan

Worked, thank you very much (put it as an answer if you want me to validate it) – Gitlow

Answer 1

The straight solution will be to use SparkR::lit() function:

df_new = withColumn(df, "new_column_name", lit("N"))

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Edit 7/17/2019

In newer Spark versions, the following also works:

df1$new_column <- "N"
df1[["new_column"]] <- "N"

Hoick

Nice! Didn't know about lit(), will delete my answer when the OP accepts yours. – Faliscan

How would I add a column full of NAs ? – Gitlow

When I attempt to do the same task, df <- withColumn(df, "col", lit(NA)), and then returnstr(df), I receive the following error: Error in FUN(X[[i]], ...) : Unsupported data type: null. I can open a new question, but thought that @DmitriySelivanov or @fmalaussena may know the answer after working with the problem. – Propinquity

df <- withColumn(df, "col", lit("NA")) should work (with " " around the NA) – Gitlow

Answer 2

There's an easier way to use SparkR::lit() that more closely mimics the syntax you tried first:

df$new_column <- lit("N")

Firefly