Spark Dataframe Drop Column By Index

It uses file-level statistics in order to perform additional skipping at file granulari. This is a guide on how to perform server-side operations with Apache Spark and ag-Grid. Rows or columns can be removed using index label or column name using this method. If a list is supplied, each element is converted to a column in the data frame. Dropping rows and columns in Pandas. To create a basic instance of this call, all we need is a SparkContext reference. After importing into H2O I have a data frame with 8,806 columns, but the first column is the target value. Finally the new DataFrame is saved to a Hive table. Spark SQL: Spark SQL is a component on top of Spark Core that introduced a data abstraction called DataFrames: Spark Streaming. Learn Data Science by working on interesting Data Science Projects for just $9. If a list of dict/series is passed and the keys are all contained in the DataFrame's index, the order of the columns in the resulting DataFrame will be unchanged. zipwithindex tutorial spark monotonically_increasing_id index how example create column scala apache-spark dataframe apache-spark-sql How to sort a dataframe by multiple column(s)? Is the Scala 2. 6: drop column in DataFrame with escaped column names. show() # alternative df. Each partition of the dataframe is extracted. ndarray, and instances of Iterator. The rows are observations and columns are variables. Dec 17, 2017 · 4 min read. In this chapter “Create, Alter and Drop – Database and Table”, we are going to learn, how we can create, alter and drop a database and table. Here, I present some of the most commonly used operations for managing columns, including how to: Rename columns; Add columns; Delete columns. It is generally the most commonly used pandas object. This is important, as the extra comma signals a wildcard match for the second coordinate for column positions. There is also a corresponding startcol so you can control the column layout as well. But the result is a dataframe with hierarchical columns, which are not very easy to work with. The inverse operation is called unstacking. //however, you still have to perform one-hot encoding when using other models that do not naturally handle categoricals like linear regression, etc. The next steps use the DataFrame API to filter the rows for salaries greater than 150,000 from one of the tables and shows the resulting DataFrame. arrange(n) if no index is passed. However, in additional to an index vector of row positions, we append an extra comma character. select("xyz"). Requirement Let's take a scenario where we have already loaded data into an RDD/Dataframe. Here the target is the dependent variable and the predictors are the independent. Python Pandas Tutorial - DataFrames. Column // The target type triggers the implicit conversion to Column scala> val idCol: Column = $ "id" idCol: org. Syntax: DataFrame. In Spark, dataframe is actually a wrapper around RDDs, the basic data structure in Spark. Vectors are typically required for Machine Learning tasks, but are otherwise not commonly used. The list of columns and the types in those columns the schema. Voir SPARK-11884 (Chute de plusieurs colonnes dans le DataFrame API et SPARK-12204 (implémenter la méthode drop pour DataFrame dans SparkR) pour plus d'informations. This blog describes one of the most common variations of this scenario in which the index column is based on another column in the DDF which contains non-unique entries. Syntax: DataFrame. Delete columns to be used as the new index. For image values generated. Renaming columns in a data frame Problem. We're using the ChickWeight data frame example which is included in the standard R distribution. 1 Documentation - udf registration. WithColumn()) and all the df function availables in a Spark Dataframe at the same time. agg() method. DataComPy’s SparkCompare class will join two dataframes either on a list of join columns. This means that it can’t be changed, and so columns can’t be updated in place. To load the DataFrame back, you first use the regular method to load the saved string DataFrame from the permanent storage and use ST_GeomFromWKT to re-build the Geometry type column. What to do: [Contributed by Arijit Tarafdar and Lin Chan]. Issue with UDF on a column of Vectors in PySpark DataFrame. They are extracted from open source Python projects. Step 1) Create a random sequence with numpy. In pandas the index is just a special column, so if we really need it, we should choose one of the columns of Spark DataFrame as ‘index’. scala columns Dropping a nested column from Spark DataFrame spark dataframe select columns (4) I have a DataFrame with the schema. For the standard deviation, see scala - Calculate the standard deviation of grouped data in a Spark DataFrame - Stack Overflow. Some bloggers opposed and some in favor of 2. We're using the ChickWeight data frame example which is included in the standard R distribution. Adding and removing columns from a data frame Problem. Let’s discuss different ways to create a DataFrame one by one. We showed that Spark is a very powerful tool for real-time analytics. 1 and above, display attempts to render image thumbnails for DataFrame columns matching Spark’s ImageSchema. Pandas: Sort rows or columns in Dataframe based on values using Dataframe. Throughout this Spark 2. how to remove the column from a java web page how to remove the column from a java web page i have a web page with account#, qtr, year if i want to remove the year column which is a drop down list from my jsp what should i do and what is the process please give a brief view. Observations in Spark DataFrame are organised under named columns, which helps Apache Spark to understand the schema of a DataFrame. Spark SQL: Spark SQL is a component on top of Spark Core that introduced a data abstraction called DataFrames: Spark Streaming. The indices ordered by label frequencies, so the most frequent value gets index 0. Consequently, we see our original unordered output, followed by a second output with the data sorted by column z. With Optimus you can handle how the output column from a transformation in going to be handled. In this usage a drop argument is ignored, with a warning. frame objects in R is very easily done by using the merge function. Use map_keys() spark function in order to retrieve all keys from a Spark DataFrame MapType column. It's also possible to use R base functions, but they require more typing. get specific row from spark dataframe apache-spark apache-spark-sql Is there any alternative for df[100, c("column")] in scala spark data frames. Spark's new DataFrame API is inspired by data frames in R and Python (Pandas), but designed from the ground up to support modern big data and data science applications. Data Engineers Will Hate You - One Weird Trick to Fix Your Pyspark Schemas May 22nd, 2016 9:39 pm I will share with you a snippet that took out a …. cases command. 8 minute read. Attributes of the DataFrame; Some of the most commonly used ones are - index, columns. In addition to Partition pruning, Databricks Runtime includes another feature that is meant to avoid scanning irrelevant data, namely the Data Skipping Index. iat to access a DataFrame; Working with Time Series. drop: dropDuplicates: Return the partition ID as a column: spark. This is important, as the extra comma signals a wildcard match for the second coordinate for column positions. Say you read a data frame from a file but you don’t like the column names. Vectors are typically required for Machine Learning tasks, but are otherwise not commonly used. Column Names of R Data Frames. The columns of a row in the result can be accessed by field index or by field name. Here we have all the date plus the Dense Vector object as well the prediction that Spark will make based upon the k-means algorithm. drop: bool, default True. Spark is an open source software developed by UC Berkeley RAD lab in 2009. Selecting pandas DataFrame Rows Based On Conditions. We'll also show how to remove columns from a data frame. Adding and removing columns from a data frame Problem. Let's discuss different ways to create a DataFrame one by one. How would I go about changing a value in row x column y of a dataframe?. ipynb # This script is a stripped down version of what is in "machine. Later, if you want to reference this column, Spark might be confused by which customer_num column you are calling. R has the duplicated function which serves this purpose quite nicely. It provides distributed task dispatching, scheduling, and basic I/O functionalities, exposed through an application programming interface. Renaming columns in a data frame Problem. DynamicFrame Class. Published: April 27, 2019 I came across an interesting problem when playing with ensembled learning. Dropping rows and columns in pandas dataframe. cannot construct expressions). head ([n]) Return the first n rows. For grouping by percentiles, I suggest defining a new column via a user-defined function (UDF), and using groupBy on that column. Pandas Spark 工作方式 单机single machine tool,没有并行机制parallelism 不支持Hadoop,处理大量数据有瓶颈 分布式并行计算框架,内建并行机制parallelism,所有的数据和操作自动并行分布在各个集群结点上。. We can also use the drop DataFrame method to remove one or more columns or rows. We can use Pandas drop function to drop rows and columns […]. In this example, we will show how you can further denormalise an Array columns into separate columns. zipwithindex tutorial spark monotonically_increasing_id index how example create column scala apache-spark dataframe apache-spark-sql How to sort a dataframe by multiple column(s)? Is the Scala 2. Read a tabular data file into a Spark DataFrame. frame objects. What’s New in 0. // IMPORT DEPENDENCIES import org. This walkthrough uses HDInsight Spark to do data exploration and binary classification and regression modeling tasks on a sample of the NYC taxi trip and fare 2013 dataset. 2 / 30 Programming Interface 3. Parse nested JSON to Data Frame in R. Python For Data Science Cheat Sheet PySpark - SQL Basics Learn Python for data science Interactively at www. We care as vectors and data. Rows or columns can be removed using index label or column name using this method. Koverse provides the records in user-selected data sets to Spark as DataFrames and automatically defines the schema of each DataFrame according to the structure of records in each Koverse data set. Build a Spark DataFrame on our data. I got the output by using the below code, but I hope we can do the same with less code — perhaps in a single line. Similar to the above method, it's also possible to sort based on the numeric index of a column in the data frame, rather than the specific name. Removes all levels by default. 1 Documentation - udf registration. Data Management. head ([n]) Return the first n rows. If a list of dict/series is passed and the keys are all contained in the DataFrame's index, the order of the columns in the resulting DataFrame will be unchanged. drop (self, labels=None, axis=0, index=None, columns=None, level=None, inplace=False, errors='raise') [source] ¶ Drop specified labels from rows or columns. For that, we have to pass list of columns to be sorted with argument by=[]. Python For Data Science Cheat Sheet PySpark - SQL Basics Learn Python for data science Interactively at www. printSchema(). This column is the index column from our Pandas dataframe. drop: bool, default False. Koverse provides the records in user-selected data sets to Spark as DataFrames and automatically defines the schema of each DataFrame according to the structure of records in each Koverse data set. Koalas is an open-source Python package…. Renaming columns in a data frame Problem. Dear Pandas Experts, I am trying to replace occurences like "United Kingdom of Great Britain and Ireland" or "United Kingdom of Great Britain & Ireland" with just "United Kingdom". For clusters running Databricks Runtime 4. We’re using the ChickWeight data frame example which is included in the standard R distribution. frame that preserved the original order of, one of the two merged, data. Each partition of the dataframe is extracted. We can term DataFrame as Dataset organized into named columns. This is a guide on how to perform server-side operations with Apache Spark and ag-Grid. However, what happens when we have an existing DataFrame and we want to update the column labels on the fly? Modifying Column Labels. How to select particular column in Spark(pyspark)? Ask Question This means that test is in fact an RDD and not a dataframe (which you are assuming it to be). Pandas DataFrame is a 2-dimensional labeled data structure with columns of potentially different types. DataFrame 4 Index 7-5 3 d c b A one-dimensional labeled array a capable of holding any data type Index Columns A two-dimensional labeled data structure with columns of potentially different types The Pandas library is built on NumPy and provides easy-to-use data structures and data analysis tools for the Python programming language. You want to add or remove columns from a data frame. You can use a regular expression here:. Don't worry, this can be changed later. Sean Taylor recently alerted me to the fact that there wasn't an easy way to filter out duplicate rows in a pandas DataFrame. To know about all the Optimus functionality please go to this notebooks. Displaying all elements in the index; How to change MultiIndex columns to standard columns; How to change standard columns to MultiIndex; Iterate over DataFrame with MultiIndex; MultiIndex Columns; Select from MultiIndex by Level; Setting and sorting a MultiIndex; Pandas Datareader; Pandas IO tools (reading and saving data sets) pd. For image values generated. 03/15/2017; 31 minutes to read +6; In this article. It's obviously an instance of a DataFrame. Let's select a few columns that will be useful for our predictive analysis and group the results as a dataframe. But I need the data types to be converted while copying this data frame to SQL DW. drop(['const', 'ints'], axis=1) # delete columns. DataFrames also allow you to intermix operations seamlessly with custom Python, R, Scala, and SQL code. Sort pandas dataframe with multiple columns. Also note that you should set the drop argument to False. Introduction to DataFrames - Python. It is generally the most commonly used pandas object. Here's an easy example of how to rename all columns in an Apache Spark DataFrame. It mean, this row/column is holding null. What’s New in 0. In R, there are multiple ways to select or drop column. It is conceptually equivalent to a table in a relational database or a data frame. to_csv('NamesAndAges. getOrCreate() The builder can also be used to create a new session:. Rows with NA values can be a pesky nuisance when trying to analyze data in R. frame that preserved the original order of, one of the two merged, data. 03/15/2017; 31 minutes to read +6; In this article. The merging operation at its simplest takes a left dataframe (the first argument), a right dataframe (the second argument), and then a merge column name, or a column to merge "on". Adding a new column; Adding a new row to DataFrame; Delete / drop rows from DataFrame; Delete a column in a DataFrame; Locate and replace data in a column; Rename a column; Reorder columns; String manipulation; Using. Spark SQL functions to work with map column (MapType) Spark SQL provides several map functions to work with MapType, In this section, we will see some of the most commonly used SQL functions. Return a new data frame created by performing a join of this data frame with the argument using the specified join type and the common, non-numeric columns from each data frame as the join key. How would I go about changing a value in row x column y of a dataframe?. Requirement Let's take a scenario where we have already loaded data into an RDD/Dataframe. Each row was assigned an index of 0 to N-1, where N is the number of rows in the DataFrame. With Optimus you can handle how the output column from a transformation in going to be handled. Check 0th row, LoanAmount Column - In isnull() test it is TRUE and in notnull() test it is FALSE. Often you may want to create a new variable either from column names of a pandas data frame or from one of the columns of the data frame. ag-Grid is a feature-rich datagrid available in Free or Enterprise versions. SQLContext Main entry point for DataFrame and SQL functionality. Use dates_m as an index for the data frame. spark sql supported types) which doesn't have varchar,nvarchar etc. Let's try with an example: Create a dataframe:. We'll also show how to remove columns from a data frame. With this explicitly set schema, we can define the columns’ name as well as their types; otherwise the column name would be the default ones derived by Spark, such as _col0, etc. Description. Collects all the elements of a SparkDataFrame and coerces them into an R data. Likewise, decimal objects can be copied, pickled, printed, used as dictionary keys, used as set elements, compared, sorted, and coerced to another type (such as float or long). Use map_keys() spark function in order to retrieve all keys from a Spark DataFrame MapType column. In Spark, dataframe is actually a wrapper around RDDs, the basic data structure in Spark. Note that you can use Optimus functions and Spark functions(. Using iterators to apply the same operation on multiple columns is vital for…. Spark also contains many built-in readers for other format. The inverse operation is called unstacking. Adding a new column; Adding a new row to DataFrame; Delete / drop rows from DataFrame; Delete a column in a DataFrame; Locate and replace data in a column; Rename a column; Reorder columns; String manipulation; Using. We retrieve rows from a data frame with the single square bracket operator, just like what we did with columns. frame: Download data from a SparkDataFrame into a R data. I had more predictors than samples (p>n), and I didn't have a clue which variables, interactions, or quadratic terms made biological sense to put into a model. how to rename the specific column of our choice by column index. 1 Documentation - udf registration. How to set Index and Columns in Pandas DataFrame? John Doe Chemist 2018-01-25 23 Emp002 William Spark Statistician 2018-01 -26 24 Drop us a line. When you do so Spark stores the table definition in the table catalog. scala columns Dropping a nested column from Spark DataFrame spark dataframe select columns (4) I have a DataFrame with the schema. join method is equivalent to SQL join like this. When working on data analytics or data science projects. Update empty string column values with ‘unknown’ Drop unused columns and columns identified as excluded in training phase; Replace null data across a number of columns; Drop duplicate rows; The transformed Spark dataframe has mapPartitions(func) function applied, as described in previous section. 0 (April XX, 2019) Installation; Getting started. Pandas drop columns using column name array. It is generally the most commonly used pandas object. This article represents a command set in the R programming language, which can be used to extract rows and columns from a given data frame. 1 and above, display attempts to render image thumbnails for DataFrame columns matching Spark's ImageSchema. Drop a variable (column) Note: axis=1 denotes that we are referring to a column, not a row. Note I had to add the param columns because drop can not only be used to drop columns, the method can also drop rows based on their index. This is a fancy way of saying “loop through each column, and apply a function to it and the next column”. Dec 17, 2017 · 4 min read. I am dropping rows from a PANDAS dataframe when some of its columns have 0 value. I had more predictors than samples (p>n), and I didn't have a clue which variables, interactions, or quadratic terms made biological sense to put into a model. Sean Taylor recently alerted me to the fact that there wasn't an easy way to filter out duplicate rows in a pandas DataFrame. Adding a new column; Adding a new row to DataFrame; Delete / drop rows from DataFrame; Delete a column in a DataFrame; Locate and replace data in a column; Rename a column; Reorder columns; String manipulation; Using. sumo leads in a Sumo query. I don’t want that percent change number to be in the trends I’m graphing! Next, I name the new category column Quarter, the new value column Price, and I “gather” every column between Q1 1996 and Q1 2018. When you do so Spark stores the table definition in the table catalog. We will learn. How to set Index and Columns in Pandas DataFrame? John Doe Chemist 2018-01-25 23 Emp002 William Spark Statistician 2018-01 -26 24 Drop us a line. For clusters running Databricks Runtime 4. Now we see our data structure has some appropriate index and column labels that make a bit of sense. You can vote up the examples you like or vote down the ones you don't like. Displaying all elements in the index; How to change MultiIndex columns to standard columns; How to change standard columns to MultiIndex; Iterate over DataFrame with MultiIndex; MultiIndex Columns; Select from MultiIndex by Level; Setting and sorting a MultiIndex; Pandas Datareader; Pandas IO tools (reading and saving data sets) pd. Data exploration and modeling with Spark. We're going to walk through how to add and delete rows to a data frame using R. Pandas drop columns using column name array. drop() method. If I know I'm going to be asking the database a certain question a bunch of times I'll even generate a temporary index to speed up my analysis, and then delete it when I'm done. The function data. I would sort the dataframe by column 'name', set the index to be this and if required not drop the column. Slightly less known are its capabilities for working with text data. Caching As with Spark, dask support caching for faster repetitive computations, but it works differntly. Another common way multiple variables are stored in columns is with a delimiter. Renaming columns in a data frame Problem. sort_index() Python Pandas : How to convert lists to a dataframe. x+ supporte plusieurs colonnes dans drop. Spark DataFrames for large scale data science | Opensource. Characteristics. Python Pandas : Replace or change Column & Row index names in DataFrame; Pandas : How to create an empty DataFrame and append rows & columns to it in python; Pandas : Sort a DataFrame based on column names or row index labels using Dataframe. {SQLContext, Row, DataFrame, Column} import. DataFrames build on top of RDD to provide partitions of data that can be processed in parallel. Rows with NA values can be a pesky nuisance when trying to analyze data in R. 0 tutorial series, we've already showed that Spark's dataframe can hold columns of complex types such as an Array of values. If you don't do that the State column will be deleted so if you set another index later you would lose the State column. Issue with UDF on a column of Vectors in PySpark DataFrame. Data Engineers Will Hate You - One Weird Trick to Fix Your Pyspark Schemas May 22nd, 2016 9:39 pm I will share with you a snippet that took out a …. sort_values() How to Find & Drop duplicate columns in a DataFrame | Python Pandas; Pandas : Sort a DataFrame based on column names or row index labels using Dataframe. In my opinion, however, working with dataframes is easier than RDD most of the time. Is H2O having trouble with the 0 for a column index?. _ import org. If a list is supplied, each element is converted to a column in the data frame. New columns can be created only by using literals (other literal types are described in How to add a constant column in a Spark DataFrame?. Posts about DataFrame written by Avkash Chauhan. The R method's implementation is kind of kludgy in my opinion (from "The data frame method …. toPandas() method should only be used if the resulting Pandas's DataFrame is expected to be small, as all the data is loaded into the driver's memory (you can look at the code at: apache/spark). Don't worry, this can be changed later. Deprecated: Function create_function() is deprecated in /www/wwwroot/autobreeding. The url column you got back has a list of numbers on the left. Predicting Airbnb Listing Prices with Scikit-Learn and Apache Spark. You can check the head or tail of the dataset with head(), or tail() preceded by the name of the panda's data frame. The goal is to extract calculated features from each array, and place in a new column in the same dataframe. If you filter your search criteria and look for only recent articles (late 2016 onwards), you would see majority of bloggers are in favor of Python 3. //however, you still have to perform one-hot encoding when using other models that do not naturally handle categoricals like linear regression, etc. csv', index=False) How to Read Multiple Dataframes to one CSV file. Before I started working as analyst, I thought master/slave are only words for describing slavery in 18th Century, or for the sexual relationship in modern age. It means moving the innermost row index to become the innermost column index. There are many different ways of adding and removing columns from a data frame. Pandas DataFrame can be created in multiple ways. Convert an Individual Column in the DataFrame into a List. Syntax: DataFrame. php on line 143 Deprecated: Function create_function() is deprecated. Note I had to add the param columns because drop can not only be used to drop columns, the method can also drop rows based on their index. frame objects. Modify the DataFrame in place (do not create a new object). Return a new data frame created by performing a join of this data frame with the argument using the specified join type and the common, non-numeric columns from each data frame as the join key. Spark Java DataFrame Transform¶ Spark DataFrames provide functionality for working with structured data easily and allows SQL functions to be used. cannot construct expressions). A pipeline is actually a workflow or sequence of tasks that cleanse, filter, train, classify, predict and validate data set. We've included 4 columns of interest in the dataframe: id, name, results, and violations using the following codes: Understand the data. I don’t want that percent change number to be in the trends I’m graphing! Next, I name the new category column Quarter, the new value column Price, and I “gather” every column between Q1 1996 and Q1 2018. In this tutorial, we will learn how to delete or drop a column or multiple columns from a dataframe in R programming with examples. To know about all the Optimus functionality please go to this notebooks. Thumbnail rendering works for any images successfully read in through the readImages function. The Spark way is to use map on the DataFrame, append each row with a new column applying the clockwise rotation matrix generation method and then converting the resulting pipeline RDD into DataFrame with the column names imposed back as part of the schema. In order to remove certain columns from dataframe, we can use pandas drop function. Pandas DataFrame is a 2-dimensional labeled data structure with columns of potentially different types. A Spark DataFrame is an interesting data structure representing a distributed collecion of data. This section provides a reference for Apache Spark SQL and Delta Lake, a set of example use cases, and information about compatibility with Apache Hive. après avoir creusé dans L'API Spark, j'ai trouvé que je peux d'abord utiliser alias pour créer un alias pour la base de données originale, utilisez withColumnRename renommer manuellement chaque colonne sur les alias, enfin à faire le join sans causer la duplication du nom de la colonne. But I need the data types to be converted while copying this data frame to SQL DW. With this explicitly set schema, we can define the columns’ name as well as their types; otherwise the column name would be the default ones derived by Spark, such as _col0, etc. randn(6,4) Step 2) Then you create a data frame using pandas. Here's an easy example of how to rename all columns in an Apache Spark DataFrame. The logistic regression model will be used to make this determination. If you are a Pandas or NumPy user and have ever tried to create a Spark DataFrame from local data, you might have noticed that it is an unbearably slow process. set_index (keys[, drop, append, …]) Set the DataFrame index (row labels) using one or more existing columns. I am dropping rows from a PANDAS dataframe when some of its columns have 0 value. This is a variant of groupBy that can only group by existing columns using column names (i. This is important, as the extra comma signals a wildcard match for the second coordinate for column positions. // IMPORT DEPENDENCIES import org. SparkSession import org. Let's say that you'd like to convert the 'Product' column into a list. This helps Spark optimize execution plan on these queries. Do not try to insert index into dataframe columns. Note I had to add the param columns because drop can not only be used to drop columns, the method can also drop rows based on their index. The Scala foldLeft method can be used to iterate over a data structure and perform multiple operations on a Spark DataFrame. 8 minute read. The article below explains how to keep or drop variables (columns) from data frame. It's also possible to use R base functions, but they require more typing. Data Engineers Will Hate You - One Weird Trick to Fix Your Pyspark Schemas May 22nd, 2016 9:39 pm I will share with you a snippet that took out a …. What is Spark SQL DataFrame? DataFrame appeared in Spark Release 1. Here is a short primer on how to remove them. A dataframe in Spark is similar to a SQL table, an R dataframe, or a pandas dataframe. how to rename the specific column of our choice by column index. Removes all levels by default. 6) organized into named columns (which represent the variables). nunique() 5. Column A column expression in a DataFrame. To create DataFrame from. So, here we use axis=1, because we wanted to drop a column. Ask Question an empty argument followed by an second index expression in order to work on columns in dataframes or to. withColumn(col_name,col_expression) for adding a column with a specified expression. This topic demonstrates a number of common Spark DataFrame functions using Python. In addition to Partition pruning, Databricks Runtime includes another feature that is meant to avoid scanning irrelevant data, namely the Data Skipping Index. drop (self, labels=None, axis=0, index=None, columns=None, level=None, inplace=False, errors='raise') [source] ¶ Drop specified labels from rows or columns. The following are top voted examples for showing how to use org. get specific row from spark dataframe; What is Azure Service Level Agreement (SLA)? How to sort a collection by date in MongoDB ? mongodb find by multiple array items; RELATED QUESTIONS.