A data frame is used for storing data tables. It is a list of vectors of equal length. For example, the following variable df is a data frame containing three vectors n, s, b.

> n = c(2, 3, 5)

> s = c("aa", "bb", "cc")

> b = c(TRUE, FALSE, TRUE)

> df = data.frame(n, s, b) # df is a data frame

Built-in Data Frame

We use built-in data frames in R for our tutorials. For example, here is a built-in data frame in R, called mtcars.

> mtcars

mpg cyl disp hp drat wt ...

Mazda RX4 21.0 6 160 110 3.90 2.62 ...

Mazda RX4 Wag 21.0 6 160 110 3.90 2.88 ...

Datsun 710 22.8 4 108 93 3.85 2.32 ...

............

The top line of the table, called the header, contains the column names. Each horizontal line afterward denotes a data row, which begins with the name of the row, and then followed by the actual data. Each data member of a row is called a cell.

To retrieve data in a cell, we would enter its row and column coordinates in the single square bracket "[]" operator. The two coordinates are separated by a comma. In other words, the coordinates begins with row position, then followed by a comma, and ends with the column position. The order is important.

Explanation:

4 0

3 years ago

What is true regarding the cellular phone concept? a. a single radio broadcast tower system enables greater frequency reuse comp

miskamm [114]

Answer:

The answer is "Option c".

Explanation:

A mobile phone is a telecom device, which uses radio signals around an internet-connected area but is served at the same fixed location with a cell tower or transmitter, enabling calls to be transmitted electronically across a wide range, to a fixed over the Internet. By increasing the amount and size of layers within the same market area, the total size of the overall system is improved, and the wrong choices can be described as follows:

In option a, It is wrong because it can't reuse radio wave frequency.
In option b, It decreases the size of the cell, that's why it is incorrect.
In option d, It reduces the size of the cells, which increases the capacity of the smartphone and it also decreases the total time of the device, that's why it is wrong.

4 0

3 years ago

Write a pseudocode statement thatsubtracts the vaiable downPayment from the variable total andassigns the reult to the variable

Virty [35]

Answer:

initialize the variables total and downPayment.

int due = total - downPayment;

Explanation:

In the programming, before use the variable in the code you have to declare the variable.

then, there are the mathematical operators in the programming to perform the mathematical calculation.

for perform addition, the operator is '+'.

for performing multiplication, the operator is '*'.

similarly, for performing subtraction, the operator is '-'.

and there is one more assignment operator in programming which is used to assign the value to the variables. The assignment operator is '='.

so, int due = total - downPayment;

in the above, the program subtracts the downPayment value from the total value and assign to the variable due which is an integer type.

5 0

3 years ago