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This chapter is from the book

This chapter is from the book

Activities

  1. Create a “named” list containing a numeric vector with 10 values (called X) and a character vector with 10 values (called Y) and a sequence of values from 1 to 10 (called Z). Use this list:

    • Print the number of elements and the element names.
    • Select the X element.
    • Select the Y element.
    • Select values of the X element that are greater than the median of X.
    • Select values of the Y element where the corresponding X element is greater than the median of X.
  2. Adapt your code to instead create a data frame containing two columns (X = a numeric vector with 10 elements, Y = a character column containing 10 elements, Z = integers 1 to 10). Use this structure:

    • Print the number of columns and the column names.
    • Select the X column.
    • Select the Y column.
    • Select values of the X column that are greater than the median of X.
    • Select values of the Y column where the corresponding X value is greater than the median of X.
  3. Further subset the data in the data frame created in the last exercise as follows:

    • Select all rows of the data where Z is greater than 5.
    • Select all rows of the data where Z is greater than 3 and X is greater than the median of X.
    • Select just the X and Z columns from the data where Z is greater than 5.
  4. Print the built-in mtcars data frame. Look at the help file for mtcars to understand the origin of the data. Use this data frame:

    • Print only the first five rows.
    • Print the last five rows.
    • How many rows and columns does the data have?
    • Look at the data in the RStudio data viewer (if you are using RStudio).
    • Print the mpg column of the data.
    • Print the mpg column of the data where the corresponding cyl column is 6.
    • Print all rows of the data where cyl is 6.
    • Print all rows of the data where mpg is greater than 25, but only for the mpg and cyl columns.
    • Create a scatter-plot matrix of your data.
    • Create a scatter-plot matrix of your data, but only using the first six columns of the data.
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