# CSV file from excel

Hi, and welcome!

Two preliminaries:

1. Please see the FAQ: What's a reproducible example (`reprex`) and how do I do one? Using a reprex, complete with representative data will attract quicker and more answers.

2. Check the homework policy.

This is a process that everyone either has or will go through to learn `R`. It helps to keep in mind that

1. Everything in `R` is an `object`, meaning it has content and properties that can be acted upon.

2. Some objects can change other objects, these are `functions`.

3. Functions are just what they sound like, school algebra: f(x) = y where f, the function object operates on one or more x `argument` objects and returns a `value` object as a result.

`R` has an endless richness of functions, but sometimes finding the right one can be a challenge. If not mentioned in your lecture notes or the text, try typing into the `R` command line

``````help(read.table)
``````

which will lead you to the function for the first step. (Hint: `csv` stands for comma separated value; also, whenever you use a function, you probably also need to assign the return value to something.)

To see the last row of the built in object `mtcars`

``````tail(mtcars,1)
#>             mpg cyl disp  hp drat   wt qsec vs am gear carb
#> Volvo 142E 21.4   4  121 109 4.11 2.78 18.6  1  1    4    2
``````

Created on 2020-04-02 by the reprex package (v0.3.0)

To see only the `mpg` values in `mtcars`, there are two ways

``````mtcars\$mpg
#>  [1] 21.0 21.0 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 17.8 16.4 17.3 15.2 10.4
#> [16] 10.4 14.7 32.4 30.4 33.9 21.5 15.5 15.2 13.3 19.2 27.3 26.0 30.4 15.8 19.7
#> [31] 15.0 21.4
mtcars[1]
#>                      mpg
#> Mazda RX4           21.0
#> Mazda RX4 Wag       21.0
#> Datsun 710          22.8
#> Hornet 4 Drive      21.4
#> Valiant             18.1
#> Duster 360          14.3
#> Merc 240D           24.4
#> Merc 230            22.8
#> Merc 280            19.2
#> Merc 280C           17.8
#> Merc 450SE          16.4
#> Merc 450SL          17.3
#> Merc 450SLC         15.2
#> Lincoln Continental 10.4
#> Chrysler Imperial   14.7
#> Fiat 128            32.4
#> Honda Civic         30.4
#> Toyota Corolla      33.9
#> Toyota Corona       21.5
#> Dodge Challenger    15.5
#> AMC Javelin         15.2
#> Camaro Z28          13.3
#> Pontiac Firebird    19.2
#> Fiat X1-9           27.3
#> Porsche 914-2       26.0
#> Lotus Europa        30.4
#> Ford Pantera L      15.8
#> Ferrari Dino        19.7
#> Maserati Bora       15.0
#> Volvo 142E          21.4
``````

Created on 2020-04-02 by the reprex package (v0.3.0)

There' a function to provide a summary. Try an obvious function name

``````obvious(your_object\$your_variable)
``````

If you have data in row/col format, what's a reasonable guess for a function to return their names?