Week 2: YellowDig: Question 1C: Counting 0's

[Niagara1000]

Hi Professor,

I do not understand this question in the Week 2 YellowDig list of questions.

"Q1-C: Counting Zeros

• What about cases where counts of zeros are important?
• What if we wanted to note here days that events did not occur?

Create a new factor that will report levels that do not occur in a sample.

x <- c("TUE","WED","FRI","SUN")
vec <- sample( x, 20, replace=TRUE )
f3 <- factor( vec )
table( f3 )

"

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Can you explain each part of the question? I am also confused about how the code is related to the questions.

Thank you, Archana

[lecy]

This code produces the table:

> x <- c("TUE","WED","FRI","SUN")
> vec <- sample( x, 20, replace=TRUE )
> f3 <- factor( vec )
> table( f3 )
f3
FRI SUN TUE WED 
  5   5   4   6 

This table omits MON, THU, and SAT.

Can you re-build the factor so that the table function returns a count of days that exist as well as days that did not occur in the dataset?

It would look similar to the table in Q1-B.

> f2 <- f[ f %in% c("MON","TUE","WED","THUR","FRI") ]
> table( f2 )
f2
 FRI  MON  SAT  SUN THUR  TUE  WED 
  14   16    0    0   10   10   14