Note

  • rows: cases or instances
  • columns: attributes or variables
  • rows and columns: data frame in R
  • code:
myFamilyIQ <- c(100,110,103,111,50)
myFamilyNames <- c("Dad","Mom","Sis","Bro","Dog")
myFamilyAges <- c(43,42,12,8,5)
myFamilyGenders <- c("Male","Female","Female","Male","Female")
myFamilyWeights <- c(188,136,84,61,44)
myFamily <- data.frame(myFamilyNames ,+
myFamilyAges ,myFamilyGenders ,myFamilyWeights ,myFamilyIQ )
myFamily
str(myFamily)
summary(myFamily)

# copy myFamilyAges vector to another storage
myFamily$myFamilyAges 
myFamilyAges <- c(myFamilyAges ,11)
myFamilyAges 
myFamily$myFamilyAges 
# try to add item to the copied vector
myFamily$myFamilyAges <- c(myFamily$myFamilyAges,11)
# output is: Error: replacement has 6 rows, data has 5

r-doc-rows-columns

Question

  • Why use the median?
    A mean may be skewed by a small number of extremely high or low values. Median may be a better number.Why use the median?
  • What is mode?
    The mode of a set of data values is the value that appears most often.

Reference