first {SparkR}R Documentation

Return the first row of a SparkDataFrame

Description

Return the first row of a SparkDataFrame

Aggregate function: returns the first value in a group.

Usage

## S4 method for signature 'SparkDataFrame'
first(x)

## S4 method for signature 'characterOrColumn'
first(x, na.rm = FALSE)

Arguments

x

A SparkDataFrame

Details

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.

See Also

Other SparkDataFrame functions: $, $<-, select, select, select,SparkDataFrame,Column-method, select,SparkDataFrame,list-method, selectExpr; SparkDataFrame-class, dataFrame; [, [[, subset; agg, agg, count,GroupedData-method, summarize, summarize; arrange, arrange, arrange, orderBy, orderBy, orderBy, orderBy; as.data.frame, as.data.frame,SparkDataFrame-method; attach, attach,SparkDataFrame-method; cache; collect; colnames, colnames, colnames<-, colnames<-, columns, names, names<-; coltypes, coltypes, coltypes<-, coltypes<-; columns, dtypes, printSchema, schema, schema; count, nrow; dapply, dapply, dapplyCollect, dapplyCollect; describe, describe, describe, summary, summary, summary,AFTSurvivalRegressionModel-method, summary,GeneralizedLinearRegressionModel-method, summary,KMeansModel-method, summary,NaiveBayesModel-method; dim; distinct, unique; dropDuplicates, dropDuplicates; dropna, dropna, fillna, fillna, na.omit, na.omit; drop, drop; dtypes; except, except; explain, explain; filter, filter, where, where; groupBy, groupBy, group_by, group_by; head; histogram; insertInto, insertInto; intersect, intersect; isLocal, isLocal; join; limit, limit; merge, merge; mutate, mutate, transform, transform; ncol; persist; printSchema; rbind, rbind, unionAll, unionAll; registerTempTable, registerTempTable; rename, rename, withColumnRenamed, withColumnRenamed; repartition; sample, sample, sample_frac, sample_frac; saveAsParquetFile, saveAsParquetFile, write.parquet, write.parquet; saveAsTable, saveAsTable; saveDF, saveDF, write.df, write.df, write.df; selectExpr; showDF, showDF; show, show, show,GroupedData-method, show,WindowSpec-method; str; take; unpersist; withColumn, withColumn; write.jdbc, write.jdbc; write.json, write.json; write.text, write.text

Other agg_funcs: agg, summarize; approxCountDistinct, approxCountDistinct, approxCountDistinct; avg, avg; countDistinct, countDistinct, n_distinct, n_distinct; count, n, n; kurtosis, kurtosis; last, last; max; mean; min; sd, sd, stddev, stddev; skewness, skewness; stddev_pop, stddev_pop; stddev_samp, stddev_samp; sumDistinct, sumDistinct; sum; var_pop, var_pop; var_samp, var_samp; var, var, variance, variance

Examples

## Not run: 
sc <- sparkR.init()
sqlContext <- sparkRSQL.init(sc)
path <- "path/to/file.json"
df <- read.json(sqlContext, path)
first(df)

## End(Not run)
## Not run: 
first(df$c)
first(df$c, TRUE)

## End(Not run)

[Package SparkR version 2.0.0 Index]