2.10 End of Chapter Exercise

Data Conversion

  1. Convert the following character string to numeric:

    1. 1,234,567 (comma as decimal mark)
    2. 1.234.566 (full stop as decimal mark)

  2. Convert the following character string to date:

    1. Jan-21-2004
    2. 01-21-2004
    3. Jaunary-21-04

Vector

  1. Create a vector of integers from 5 to 99.

  2. Create a vector of five zeros.

  3. Create a vectors of dates from January 1st, 2014 to January 5th, 2014.

Factor

Using a numeric vector x = c(1,2,3,3,5,5,6,7,8,9,9,10):

  1. create a factor vector that divides the data into three groups of the same lenght: High, Middle, and Low. (Hint: Use the function cut)

  2. create a factor vector that divides the data into three groups: Above average, between average and lower quartile, and below lower quartile. (Hint: Use the function cut and quartile)

Vector

  1. Create two new numeric vectors x and y.
  2. Create a new vector \(z = x + y\).

Matrix

  1. Create two new numeric vectors x and y.
  2. Create a dataframe from two newly created vectors.
  3. Create a new column in the dataframe that \(w = x - 2 \times y\).

Function

  1. Write the following function:
    • take three numerical numbers,
    • calculate the product of three numerical inputs,
    • display the value, and
    • return the value as function output.
  2. Write the following function:
    • take three numerical numbers, but the last input has default value of 1,
    • calculate the sum of the first two numerical inputs, and then the result is multipled by the third input,
    • display the value, and
    • return the value as function output.

Packages

  1. Install package quantmod.
  2. Load the package quantmod.