Data structures

Data structures

1. Data frames

   • Definition
     • Two-dimensional heterogeneous array-like structure
       • Each column contains values of one variable
       • Each row contains one set of values from each column
   • Characteristics
     • The column names should be non-empty
     • The row names should be unique
     • The data stored a data frame can be numeric, factor or character type
     • Each column contain same number of data item
     • A data frame is made up of vectors

2. Lists

   • Definition
     • A collection of items stored at contiguous memory locations, they are different from arrays, because they are heterogeneous
   • Characteristics
     • Used to organize data
     • Heterogeneous
     • 1-Dimensional

3. Series

   • Definition
     • Series is a one-dimensional array like structure with homogeneous data.
       • For example a collection of integers: 25, 78, 4, 19
   • Characteristics
     • Homogeneous data
     • Size immutable
     • Values of data Mutable
     • 1D labeled homogeneous array

4. Array

   • Definition
     • A collection of items stored at contiguous memory locations: Store multiple items of same type together
   • Characteristics
     • Homogeneous
     • Used to organize data
     • 1-Dimensional

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