How to combine 2 lists to create a dataframe in R?
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How to combine 2 lists to create a dataframe in R?

How to combine 2 lists to create a dataframe in R?

This recipe helps you combine 2 lists to create a dataframe in R

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Recipe Objective

Dataframes are data-objects in R which are combination of vectors of same length. It is represented as a two-dimensional array or a table where columns represent variables of the dataset while rows are the observations in it. Unlike matrices, dataframes contains different datatypes.

Often dataframes are created by loading a dataset from existing storage like an excel file, csv file. But we can also create a dataframe from vectors or lists in R. This recipe demonstrates how to create a dataframe combining 2 lists.

Step 1: Creating 2 lists

We are going to take an example of student dataset which has variables like marks and name. To create this dataframe, we will first create 2 lists named "marks" and "name".

Note: the length of each lists has to be same

name = list('Tom', "Harry", "David", "Daniel") marks = list(50,60,35,95)

Step 2: Creating a Dataframe

We use data.frame() and unlist() functions to create a dataframe using lists. unlist() function is used to covert list to vector so that we can use it as "df" argument in data.frame() function.

Syntax:

1. data.frame(df, stringAsFactors)

where:

  1. df = is matrix or collection of vectors that needs to be joined;
  2. stringAsFactors = if TRUE, it converts string to vector by default;

unlist(x, recursive = TRUE, use.names = TRUE)

where:

  1. x = lists;
  2. recursive = By defalut it's TRUE but if FALSE, the function won't recurse beyond first level of list;
  3. use.names = By default it's TRUE and its meant to preserve the naming information;
student = data.frame(unlist(name),unlist(marks)) ​ #to name the columns we use names() function names(student) = c("Name","Marks") ​ ​ student
Tom	50
Harry	60
David	35
Daniel	95

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