count
# count :: Table, String -> Table
1 What is the Domain of count?
2 What is the Range of count?
3 What do you suspect the String in the Domain will describe?
Suppose we wanted to know how many animals had 4 legs…
Type count(animals-table, "legs") into the Interactions Area and click "Enter"
4 What did the expression produce?
5 How many animals had 4 legs?
6 Think of another question you might be able to answer with the count function.
7 Fill in the blanks with the code you’d write.
function-name (table-name :: Table, column-name :: String)
8 Tables that summarize data with a count are commonly used in the real world. Give two examples of where you’ve seen them before:
-
Example 1:
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Example 2:
9 Newscasters and journalists often incorporate data into their reporting. How else might they display this information, besides using a table?
first-n-rows
10 Type first-n-rows(animals-table, 5). What happens?
11 If we wanted a table of the first 3 rows of the animals-table, what code would you write?
12 What is the Contract for first-n-rows?
★ What happens when you type first-n-rows(sort(animals-table, "pounds", true), 5)?
Note: The Domain for first-n-rows is Table, Number. In this case, the output of sort(animals-table, "pounds", true) is the Table!
★ See if you can figure out how to compose the code that would generate a table of the 10 oldest animals!
function-name (Table, Number)
These materials were developed partly through support of the National Science Foundation, (awards 1042210, 1535276, 1648684, 1738598, 2031479, and 1501927). 
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