Spark dataframe select first n rows. to get only the first row we have to specify 1.
- Spark dataframe select first n rows. tail:_*) answered Oct 11, 2018 at 20:00.
- Spark dataframe select first n rows. If the frame is sorted and you can guarantee it is in the first row, here is one method. window import Window. first=df. – mck. I have tried using the following code, but that leaves my dataframe parquet output empty: updated_bulk=bulk_spark_df. columns[:105]) But since you tagged it with scala too, here's a scala solution: Spark Dataframe: Select distinct rows. (SELECT product,category,revenue,dense_rank() OVER (PARTITION BY category ORDER BY revenue DESC) as rank. spark. filter(lambda line: line != header) So which alternatives are available? Spark SQL can convert an RDD of Row objects to a DataFrame, inferring the datatypes. count() to give me only n and not all rows, is it possible ? Jul 14, 2018 · scala> val results = spark. We can use this head() function to get only the first row of the dataframe, for that, we pass '1' as an argument to this function. Just a general question. getOrCreate() # Create the dataframe with sample data. limit(1) df_res=df_res. from pyspark. csv") headers = data. w = Window. Sep 6, 2016 · The time it takes to count the records in a DataFrame depends on the power of the cluster and how the data is stored. head(3) Now you see that the header still appears as the first line in my dataframe here. Example 2: Get the first row for a particular column. master('local'). data=spark. It will return the first non-null value it sees when ignoreNulls is set to true. Changed in version 3. See full list on sparkbyexamples. # Using DataFrame. I tried two ways to find distinct rows from parquet but it doesn't seem to work. first() rdd. filter() function returns a new DataFrame or RDD with only the rows that meet Jan 9, 2019 · Here are several options that I can think of since the data bricks module doesn't seem to provide a skip line option: Option one: Add a "#" character in front of the first line, and the line will be automatically considered as comment and ignored by the data. toDS () or to DF () method) Then you can just call show (10) method. nint, optional. First option is to rely on a join if your list is 'big': data = [[value] for value in lst] safelist = spark. print(a) . Read a CSV file in a table spark. Notes. iloc is not available, and I often see this approach, but this only works on an RDD: header = rdd. Performance optimizations can make Spark counts very quick. first (). # DataFrame using head() print( df. first ¶. If all values are missing, then NA is returned. Given below is the syntax. print("Top 2 rows ") . head(2) . between_time (start_time, end_time) Select values between particular times of the day (example: 9:00-9:30 AM). The fields in it can be accessed: like attributes ( row. Apr 21, 2021 at 15:00. A combination of one or more values, operators, and SQL functions that evaluates to a value. sql("select _c1, count(1) from data group by _c1 order by count(*) desc") results: org. The keys of this list define the column names of the table, and the types are inferred by sampling the whole dataset, similar to the inference that is performed on JSON files. It will return the first row of DataFrame. We then get a Row object from a list of row objects returned by DataFrame. #select first column in DataFrame. src and df2. Get distinct rows based on one column. Example 1: Program to get the first row of the dataset. March 27, 2024. Jun 20, 2020 · That is for each element in the tuple, we select from the pyspark dataframe the first 1 row that d is larger than the tuple number and col1 is equal to the tuple string. *, ROW_NUMBER() OVER (ORDER BY col_name DESC) rn FROM Employee e ) WHERE rn = N N is the nth highest value required from the column Output: Dec 22, 2021 · 0. Attemp 1: Dataset<Row> df = sqlContext. Both methods take one or more columns as arguments and return a new DataFrame after sorting. val example1: String = firstRow. But, when I tried to print the headers, I got encoded values. getOrCreate() # Create the dataframe. show() #+---+-----+ #| id| letters| #+---+-----+ #| 1|[a, b, c]| #| 2|[d, e Jul 18, 2022 · Method 3: Using SQL Expression. builder. By default n = 5, it return first 5 rows if value of n is not passed to the method. DataFrame = [_c1: string, count(1 Apr 21, 2021 · 1,823 2 15 35. drop() are aliases of each other. Mar 27, 2024 · The pandas. 5 of total rows. Row [source] ¶. val w2 = Window. If ‘all’, drop a row only if all its values are null. Seed for sampling (default a random seed). FROM productRevenue) tmp. PySpark doesn’t have a map () in DataFrame instead it’s in RDD hence we need to convert DataFrame to RDD first and then use the map (). Sample method. // grab the product from the first row. a = dataframe. PartitionBy('id') df. Will return this number of records or all records if the DataFrame contains less than this number of records. Sampled rows from given DataFrame. foreachPartition { partitionedRows: Iterator[Model1] =>. sql("select item_code_1 from join_table limit 100") pyspark. filter(col("row_number") <= n) but this is in no way performant when the data contains millions or billions of rows because it pushes the data into one partition and I get OOM. Returns DataFrame. cheseaux. DataFrame. at_time (time [, asof, axis]) Select values at particular time of day (example: 9:30AM). May 30, 2022 · 1. Aug 11, 2020 · 0. Now, this becomes a little easier to work with. bricks csv module; Option two: Create your customized schema and specify the mode Mar 27, 2024 · 2. This allows you to select an exact number of rows per group. apache. asDict () ['col_name'] will get you a value. Sep 15, 2022 · 2. DataFrame. Returns a new :class: DataFrame by skipping the first n rows. The LIMIT clause is used to constrain the number of rows returned by the SELECT statement. take(2) #First two rows to be skipped The idea was to then use filter and not read the headers. default 1. show() This method will return a new DataFrame that contains the top 10 rows. persist ([storageLevel]) Mar 27, 2024 · 1. sql("""SELECT idx, value, ROW_NUMBER() OVER (PARTITION BY idx ORDER BY c DESC) as r. take. Only difference is that I need to select the first 3 rows of each group. read(). show. num_value has the smallest value. d>y). functions. Mar 27, 2024 · In PySpark Find/Select Top N rows from each group can be calculated by partition the data by window using Window. head(). 10th row in the dataframe. median ( [axis, skipna, …]) Return the median of the values for the requested axis. # or. key) like dictionary values ( row[key]) key in row will search through row keys. desc()). SELECT * FROM ( SELECT e. union(dft) But I think this might have efficiency problem, I do not know if I were DataFrame. spark. Option 1. Spark will execute the same query differently on Postgres (predicate pushdown filtering is supported), Parquet (column pruning), and CSV files. val firstRow: OutputFormat = fxRatesDF. Collect (Action) - Return all the elements of the dataset as an array at the driver program. read . distinct(). mode ( [axis, numeric_only, dropna]) Get the mode (s) of each element along the selected axis. col1==x). Output: id name subjects. Method 2: Use limit () df. For example df. withColumn("row_number", row_number over window). – Mar 13, 2018 · 2. monotonically_increasing_id(). df. columns) to get the number of columns in the DataFrame. Imagine n=2 and in one group of A, B is [1, 2, 3] and C is [1, 3, 2]. If one of the column names is ‘*’, that column is expanded Mar 27, 2024 · 2. join(safelist, on='meta_info') filtered. An expression with an optional assigned name. sql (“SELECT * FROM my_view WHERE column_name between value1 and value2”) Example 1: Python program to select rows from dataframe based on subject2 column. Row] [source] ¶ Returns the first row as a Row. functions import row_number,lit. When the header option is set to true (the default), Spark includes the header row in the output file. take(n) and then select only these columns from the Dataset : ds. team. I've added args and kwargs to the function so you can access the other arguments of DataFrame. For the first row, I know I can use df. The agg function allows me to select the top value with the help of max function or by applying sort initially and then using the first function. Feb 14, 2018 · Spark comes with SQL syntax, and SQL is a great and expressive tool for this problem. You can further group the data in partition into batches if need be. orderBy (*cols, **kwargs) Returns a new DataFrame sorted by the specified column(s). spark-sql doc. So you can do like limited_df = df. Oct 28, 2018 · Here's how to do it with the API functions. See bottom of post for example. You can also get the column count using len(df. Apr 15, 2019 · I have a dataframe with 10609 rows and I want to convert 100 rows at a time to JSON and send them back to a webservice. This uses the spark applyInPandas method to distribute the groups, available from Spark 3. It returns an Jan 20, 2021 · How to copy first n rows in dataframe in spark? Ask Question Asked 3 years, Reduce size of Spark Dataframe by selecting only every n th element with Scala. Let's say 4 million rows out of 15 million. See below for some examples. (limit 10 in your case) EXAMPLE: sqlContext. In general, this clause is used in conjunction with ORDER BY to ensure that the results are deterministic. dtypes) by retrieving all column names and data types as a list of tuples and applying len() on the list. It returns a new DataFrame after selecting only distinct column values, when it finds any rows having unique values on all columns it will be eliminated from the results. fraction is required and, withReplacement and seed are optional Description. 0, 1. Quick Examples of Get First N Rows of DataFrame. In order to keep the original dataframe df, we will be assigning the sliced dataframe to df_new. 3. count() to find the number of unique rows in the PySpark DataFrame. Nov 16, 2019 · 1. Mar 27, 2024 · Use df. df_new = df[:10] # Option 1. default None If specified, drop rows that have less than thresh Oct 25, 2023 · Related terms: There are two common ways to select the top N rows in a PySpark DataFrame: Method 1: Use take () df. parquet("location. To count null values in columns, you can Dec 7, 2006 · the answer to What are the best-selling and the second best-selling products in every category is as follows. filter(df. first. Suppose your DataFrame were the following: df. In this case the first window of your solution would drop the second row (C=3), although the wanted output dataframe should consist of the first and second row – Mar 27, 2021 · PySpark map () Transformation is used to loop/iterate through the PySpark DataFrame/RDD by applying the transformation function (lambda) on every element (Rows and Columns) of RDD/DataFrame. The following examples show how to use each of these . orderBy(col("salary")) Mar 27, 2024 · df = spark. Select Rows by Index using Pandas iloc[] pandas. Oct 18, 2017 · I am looking for a way to select columns of my dataframe in PySpark. So, desired output is (sorted by num_value ): I know how to implement this using SQL, but I have some difficulties with PySpark/Spark SQL. functions import concat,lit,substring. column names (string) or expressions ( Column ). Therefore pick one appropriate for your situation. New in version 1. Does anybody know how to remove the entire first row of a pyspark dataframe. sql. filter. Use "limit" in your query. Pyspark Select Distinct Rows. textFile("myFile. SELECT idx, value, COUNT(*) as c. So I'm also including an example of 'first occurrence' drop duplicates operation using Window function + sort + rank + filter. If we have 2000 rows and you want to get 100 rows, we must have 0. printSchema ([level]) I am trying to get the rows which have 'UseCase' value as 'Unidentified'. persist ([storageLevel]) Sets the storage level to persist the contents of the DataFrame across operations after the first time it is computed. sortWithinPartitions (*cols, **kwargs) Returns a new DataFrame with each partition sorted by the specified column(s). Select First Row From a Group. 0 and Python 3. Register your dataframe as a temp table, and then group and window on it. spark=SparkSession. sql import SparkSession. #group DataFrame by team column. createDataFrame(data = data, schema = columns) df. Mar 1, 2021 · You can get a list of column names from df. Parameters n int, optional. show(n: int = 20, truncate: Union[bool, int] = True, vertical: bool = False) → None [source] ¶. partitionBy () function, running row_number () function over the grouped partition, and finally filter the rows to get top N rows, let’s see with a DataFrame example. When the header option is set to false, Spark excludes the May 6, 2020 · You can do something like: let's say your main df with 70k rows is original_df. Note: the function is non-deterministic because its results depends on the order of the rows which may be non-deterministic after a shuffle. Jan 4, 2022 · Method 1 : Using __getitem ()__ magic method. Windows, but they always seem to imply ordering the values Prints the first n rows to the console. Since DataFrame is immutable, this creates a new DataFrame with selected Returns a new :class: DataFrame by skipping the first n rows. Rows are constructed by passing a list of key/value pairs as kwargs to the Row class. Parameters. orderBy(desc("count")) df. Mar 27, 2024 · PySpark filter() function is used to filter the rows from RDD/DataFrame based on the given condition or SQL expression, you can also use where() clause instead of the filter () if you are coming from an SQL background, both these functions operate exactly the same. think of filter or where that you use to filter out rows you don't want to include in a result dataset. You can even do . Oct 30, 2023 · by Zach October 30, 2023. How can we select the first n rows of a Pandas DataFrame? Jun 13, 2022 · There are many answers for selecting the top n rows, but I dont't need order and am not sure whether ordering would not introduce unnecessary shuffling. When choosing one of these methods, always remember that they have different return types. Below is a quick snippet that give you top 2 rows for each group. pyspark. appName('scratch'). truncatebool or int, optional. Method 2: Select Rows where Column Value is in List of Values. If you want to get more rows than there are in DataFrame, you must get 1. For completeness, I have written down the full code in order to reproduce the output. to get only the first row we have to specify 1. collect () [index_position] Where, dataframe is the pyspark dataframe. Returns If n is greater than 1, return a list of class:Row. Mar 27, 2024 · PySpark. The function by default returns the first values it sees. May 25, 2017 · 68. Sep 20, 2021 · The only method I can think of is using row_number without partition like. Return the first 2 rows of the DataFrame. distinct(); But throws. I want to select the second row for each group of names. ('George', datetime(2020, 3, 24, 3, 19, 58), datetime(2018, 2, 24, 3, 22, 55)), Aug 1, 2019 · 1. Currently, I'm adding row_number to records within each partition and selecting the required percentage of records from each partition. head() method returns the first n rows of dataframe. first(), but not sure about columns given that they do not have column names. over(w)) #you can use max, min, sum, first, last depending on how you want to treat duplicates. subtract (other) Return a new DataFrame containing rows in this DataFrame but not in another DataFrame. FROM (. 16 mins read. show() Other option is to filter your dataset, but still, it can be relevant to broadcast your list in order to May 31, 2017 · I am referring to n_rows equivalent of pandas in spark-csv, like: pd_df = pandas. (merged_mas_bulk_spark_df. functions as F last=df. This is what I did in notebook so far 1. Without an index/ordering column, the "first" row is not well-defined. We can select the first row from the group using Spark SQL or DataFrame API, in this section, we will see with DataFrame API using a window function row_rumber and partitionBy. sql("SELECT text FROM yourTable LIMIT 10") Or you can select all from your table and save result to DataFrame or DataSet (or to RDD, but then you need to call rdd. isin('A','B')). Sorted by: 0. Created using Sphinx 3. Mar 12, 2021 · This solution works for the example dataframe. # Get the first row use head() Aug 12, 2021 · You can use a combination of rand and limit, specifying the required n number of rows. iloc[] with the syntax [start:stop:step]; where start indicates the index of the first row to start, stop indicates the index of the last row to stop, and step indicates the number class pyspark. Examples Jun 4, 2019 · A straightforward approach would be to sort the dataframe backward and use the head function again. Prints the first n rows to the console. Remove the Header while writing to a CSV file. Using iloc [] to Drop First N Rows of DataFrame. orderBy (*cols, **kwargs) Returns a new DataFrame sorted by the specified column(s). ). # Create SparkSession. Dec 1, 2015 · Here's an alternative using Pandas DataFrame. columns, and select the first 105 values in the list: df2 = df. read_csv("file_path", nrows=20) Or it might be the case that spark does not actually load the file, the first step, but in this case, why is my file load step taking too much time then? I want. select(df. // Spark DataFrame where() Syntaxes. You should iterate over the partitions which allows the data to be processed by Spark in parallel and you can do foreach on each row inside the partition. orderBy(F. Select Single & Multiple Columns From PySpark. This method should only be used if the resulting array is expected to be small, as all the data is loaded into the driver’s memory. 1. [\x00A\x00Y\x00 \x00J\x00u\x00l\x00y\x00 \x002\x000\x001\x006\x00] What is the correct way to read a CSV file and skip the first two rows? Here is the solution with Spark 3. limit(10). iloc[] Sep 6, 2016 · Explanation: we must take a fraction of data. If ‘any’, drop a row if it contains any nulls. From the above dataframe employee_name with James has the same values on all Apr 9, 2019 · Spark dataframe select a column from a row. parquet"). It is important that I select the second purchase for each name (by datetime). In this example, I will be extracting the first four rows and process them. If one of the column names is ‘*’, that column is expanded to include all columns in the current DataFrame. If set to True, truncate strings longer than 20 chars by default. #select all columns except first column in DataFrame. We will create a Spark DataFrame with at least one row using createDataFrame (). subtract(limited_df) and you will get the remaining rows. sort (*cols, **kwargs) Returns a new DataFrame sorted by the specified column(s). You can use the following syntax to select the first row by group in a PySpark DataFrame: from pyspark. orderBy(lit('A')) #filter DataFrame to only show first row for each team. If we only want the first 2 rows, then we can either slice by the actual index, or use -1. limit function is invoked to make sure that rounding is ok and you didn't get more rows than you specified. I'm stuck with a similar use case as in SPARK DataFrame: select the first row of each group. show() Method 2: Select All Columns Except Specific One by Index. head (n) to get the first n rows of the DataFrame. Cannot have map type columns in DataFrame which calls set operations. Align two objects on their axes with the specified join method. Use pandas. // or, you can map over and grab the row (again, type-safe) val example2: String = fxRatesDF. named_expression. # Example 1: Get the first n rows of. val window = Window. limit() for the subtracted df too if needed. Oct 24, 2019 · I am a newbie to azure spark/ databricks and trying to access specific row e. take(10) This method will return an array of the top 10 rows. Returns the first num rows as a list of Row. Select all matching rows from the table references after removing duplicates in results. 1. It takes one optional argument n (number of rows you want to get from the start). spark = SparkSession. iloc[n:], substitute n with the integer number specifying how many rows you want to delete. A row in DataFrame . limit(50000) for the very first time to get the 50k rows and for the next rows you can do original_df. answered Sep 1, 2023 at 19:22. Remember index starts from 0, you can use pandas. tail:_*) answered Oct 11, 2018 at 20:00. Scala spark, show distinct column value and count number of occurrence. 0. By using SQL query with between () operator we can get the range of rows. However, it is not a general solution to the described problem. partitionBy("department"). But when I'm trying to choose 26 % Jul 15, 2021 · 1 Answer. It's easier for Spark to perform counts on Parquet files than CSV/JSON files. support Finally, since it is a shame to sort a dataframe simply to get its first and last elements, we can use the RDD API Fraction of rows to generate, range [0. partitionBy('team'). types. pct_change ( [periods]) Percentage change between the current and a prior element. sparkDF. Aggregate function: returns the first value in a group. Here is the data to build dataframe: data = [. You can select the single or multiple columns of the DataFrame by passing the column names you wanted to select to the select() function. 'Number!='part=') Number is a column and part is a data occurance in the first row. May 20, 2017 · data = sc. ¶. . For instance, 4 million is 26. seed int, optional. Row can be used to create a row object by using named arguments. That could be as follows (using Scala API): val cdf: DataFrame = Use result data frame however you wish. Mar 6, 2019 · 4. Example: Python code to access rows. Number of rows to show. Ask Question Asked 4 years, Relationship between the squares of first n natural numbers and first n natural odd numbers. ), Mar 27, 2024 · Using PySpark select () transformations one can select the nested struct columns from DataFrame. In Spark, you can control whether or not to write the header row when writing a DataFrame to a CSV file, by using the header option. If we only want the last row (index of 4 ), once again, we can either slice by the actual index, or use -1. Details. dataframe is the dataframe name created from the nested lists using pyspark. Spark dataframes are unordered. pandas_api ([index_col]) Converts the existing DataFrame into a pandas-on-Spark DataFrame. I used orderby to sort by name and then the purchase date/timestamp. df_first_3 = df. (intersect, except, etc. select (*cols) (transformation) - Projects a set of expressions and returns a new DataFrame. FxRate. Feb 6, 2016 · The getrows() function below should get the specific rows you want. Python3. support import pyspark. expression. Use pyspark distinct() to select unique rows from all columns. Jul 18, 2021 · Method 1: Using collect () This is used to get the all row’s data from the dataframe in list format. I have 5 columns and want to loop through each one of them. It is not allowed to omit a named argument to represent that the value is None or missing. Mar 27, 2024 · Spark where() function is used to filter the rows from DataFrame or Dataset based on the given condition or SQL expression, In this tutorial, you will learn how to apply single and multiple conditions on DataFrame columns using where() function with Scala examples. createDataFrame(data=data, schema=["meta_info"]) filtered = df. columns[0]). first → Optional [pyspark. . However this is not practical for most Spark datasets. com Jun 6, 2021 · Method 1: Using head () This function is used to extract top N rows in the given dataframe. # Below are some quick examples. g. forma pyspark. Spark Core; Resource Management; pyspark. If n is 1, return a single Row. Enabled by default. We then use the __getitem ()__ magic method to get an item of a particular column name. If all values are null, then null is returned. brian_ds. I'm unsure of how to remove it. If set to True, truncate strings longer Sep 16, 2022 · Get the First Row of Pandas using head () This function will default return the first 5 rows of the Dataframe. I have looked at. colsstr, Column, or list. Number of rows to return. When you read these files into DataFrame, all nested structure elements are converted into struct Oct 6, 2023 · You can use the following methods to select columns by index in a PySpark DataFrame: Method 1: Select Specific Column by Index. head()) # Example 2: Get first n rows of DataFrame. 11. Projects a set of expressions and returns a new DataFrame. columns. 0: Supports Spark Connect. column Jan 24, 2017 · Pandas group by two columns and get top n rows of each value of one of the columns sorted in descending order 0 Sorting columns and selecting top 'n' from a grouped column in pandas dataframe DataFrame. var == df2. See here for more details. 66 % of 15 million. first [source] ¶ Returns the first row as a Row. head (n) where, n specifies the number of rows to be extracted from first. While working with semi-structured files like JSON or structured files like Avro, Parquet, ORC we often have to deal with complex nested structures. Share Jul 10, 2020 · one can extract a subset of rows and store it in another pandas data frame. You can use either sort() or orderBy() function of PySpark DataFrame to sort DataFrame by ascending or descending order based on single or multiple columns. Jan 8, 2020 · Window function shuffles data, but if you have duplicate entries and want to choose which one to keep for example, or want to sum the value of the duplicates then window function is the way to go. You don't delete rows from dataframes, they are immutable. 0. This is usually useful after a filter or other operation that returns a sufficiently small subset of the data. val firstNCols = ds. select(*cols: ColumnOrName) → DataFrame [source] ¶. sqlDF. I have two Spark dataframes: I need to return top 3 rows from df2 dataframe where df1. Parquet files store counts in the file footer, so Spark doesn't need to read all the rows Below we will go through at least three options. Actions vs Transformations. This is not guaranteed to provide exactly the fraction specified of the total count of the given DataFrame. Jan 1, 2019 · Better, if you can, to first filter the dataframe smaller before doing that in some way. sampleBy(), but I don't need a fraction but a maximal absolute amount of rows. Syntax: spark. createDataFrame(. agg(first( value col ). iloc[] attribute is used for integer-location-based indexing to select rows and columns in a DataFrame. Aug 5, 2020 · Output : Method 1 : Using head() method. select(firstNCols. show() Method 3: Select Rows Based on Multiple Column Conditions. No longer dealing with `Row`s, but `OutputFormat`s. If you hurry below are quick examples of how to get the first N Rows of DataFrame. import pyspark. Syntax: dataframe. rand()). 2. You can also do sorting using PySpark SQL sorting functions. Once processed, the values in 'UseCase; column will be replaced with proper UseCase (as present in 4, etc. 4. Sample. Spark DataFrame where () Syntaxes. index_position is the index row in dataframe. Use len(df. If set to a number greater than one, truncates long strings to length truncate and align cells right. # using head() Aug 1, 2016 · dropDuplicates keeps the 'first occurrence' of a sort operation - only if there is 1 partition. head, firstNCols. Oct 6, 2023 · You can use the following methods to select rows based on column values in a PySpark DataFrame: Method 1: Select Rows where Column is Equal to Specific Value. Tis will give you the desired result. I have tried using the LIMIT clause of SQL like temptable = spark. DISTINCT. I need to select n rows from very large data set which has millions of rows. It will return the first non-missing value it sees when na. show(truncate=False) 1. select. Number of records to return. first¶ DataFrame. rm is set to true. You would need to build a query to exclude whatever rows you don't want. Use DataFrame. Mar 18, 2024 · In this article, we’ve discovered six ways to return the first n rows of a DataSet, namely show(n), head(n), take(n), takeAsList(n), limit(n), and first(). ‘any’ or ‘all’. What I've already written is: dft=df. iloc[] the indexing syntax [n:] with n as an integer to select the first n rows from pandas DataFrame. collect (). Select all matching rows from the table references. limit(n) Note it is a simple implementation, which provides you a rough number of rows, additionally you can filter the dataset to your required conditions first , as OrderBy is a costly operation pyspark. Mar 27, 2024 · 2. If set to True, print output rows vertically (one line per Oct 11, 2018 · Given that your Dataset is ds, you can extract the first n columns into an Array : val n = 2. 0]. dropna() and DataFrameNaFunctions. // Select First Row From a Group. At the end, in section Time Comparison we will show, using a random dataframe, the various times of execution. ix id ok ek ga gt oq ea lq bj