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Select elements in objects

This exercise focuses on extracting different elements from objects in R. Your workspace environment includes the objects created previously: two numeric vectors numvec1 and numvec2, one character vector charvec, a matrix nummtx, and a dataframe dataframe. Type the name of each object in the console to view them again if you wish. The dplyr package is also loaded.

You will get experience selecting elements from each type of object (vector, matrix, and dataframe).

This exercise is part of the course

R For SAS Users

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Exercise instructions

  • Select the 2nd element in vector charvec
  • Select the 2nd column of matrix nummtx
  • Pull column numvec1 from dataframe dataframe assign it to an object named id
  • Pull column charvec from dataframe dataframe determine the class of charvec

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

# Select the 2nd element in vector charvec
charvec[___]

# Select the 2nd column of matrix nummtx
nummtx[___]

# Pull column numvec1 from dataframe assign it to id
___ <- ___ %>% 
  ___

# Pull column charvec from dataframe and determine the class of charvec
___ %>% 
  ___ %>% 
  ___
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