| first {SparkR} | R Documentation |
Aggregate function: returns the first value in a group.
first(x, ...) ## S4 method for signature 'SparkDataFrame' first(x) ## S4 method for signature 'characterOrColumn' first(x, na.rm = FALSE)
x |
a SparkDataFrame or a column used in aggregation function. |
... |
further arguments to be passed to or from other methods. |
na.rm |
a logical value indicating whether NA values should be stripped before the computation proceeds. |
The function by default returns the first values it sees. It will return the first non-missing value it sees when na.rm is set to true. If all values are missing, then NA is returned. Note: the function is non-deterministic because its results depends on order of rows which may be non-deterministic after a shuffle.
first(SparkDataFrame) since 1.4.0
first(characterOrColumn) since 1.4.0
Other SparkDataFrame functions: SparkDataFrame-class,
agg, alias,
arrange, as.data.frame,
attach,SparkDataFrame-method,
broadcast, cache,
checkpoint, coalesce,
collect, colnames,
coltypes,
createOrReplaceTempView,
crossJoin, cube,
dapplyCollect, dapply,
describe, dim,
distinct, dropDuplicates,
dropna, drop,
dtypes, exceptAll,
except, explain,
filter, gapplyCollect,
gapply, getNumPartitions,
group_by, head,
hint, histogram,
insertInto, intersectAll,
intersect, isLocal,
isStreaming, join,
limit, localCheckpoint,
merge, mutate,
ncol, nrow,
persist, printSchema,
randomSplit, rbind,
rename, repartitionByRange,
repartition, rollup,
sample, saveAsTable,
schema, selectExpr,
select, showDF,
show, storageLevel,
str, subset,
summary, take,
toJSON, unionAll,
unionByName, union,
unpersist, withColumn,
withWatermark, with,
write.df, write.jdbc,
write.json, write.orc,
write.parquet, write.stream,
write.text
Other aggregate functions: avg,
column_aggregate_functions,
corr, count,
cov, last
## Not run:
##D sparkR.session()
##D path <- "path/to/file.json"
##D df <- read.json(path)
##D first(df)
## End(Not run)
## Not run:
##D first(df$c)
##D first(df$c, TRUE)
## End(Not run)