R base functions

head is a simple function that shows the first n values in an object, with default n = 6. Additionally, if you include a negative sign in front of your n integer, it will display the object without the last n items.

Examples

Using the Iowa liquor sales file, which columns contain the Store Number, Store Name, Address, City, and Zip Code?

Click to see solution 
library(data.table)
options(repr.matrix.max.cols=50)


iowa_1000 <- fread("/anvil/projects/tdm/data/iowa_liquor_sales/iowa_liquor_sales.csv", nrows=1000)

head(iowa_1000[, .(`Store Number`, `Store Name`, `Address`, `City`, `Zip Code`)])
Store Number	Store Name	Address	City	Zip Code
2846	CVS PHARMACY #8443 / CEDAR RAPIDS 	3419 16TH AVE SW 	CEDAR RAPIDS 	52404
3894	SMOKIN' JOE'S #6 TOBACCO AND LIQUOR	1404 1ST AVE NE 	CEDAR RAPIDS 	52402
2558	HY-VEE FOOD STORE / MOUNT PLEASANT 	1700 E WASHINGTON 	MOUNT PLEASANT	52641
4680	AFAL FOOD & LIQUOR / DES MOINES    	4121 SE 14TH ST     	DES MOINES    	50320
2590	HY-VEE FOOD STORE #5 / CEDAR RAPIDS	3235 OAKLAND ROAD NE	CEDAR RAPIDS 	52402
4126	SAM'S MAINSTREET MARKET / SOLON 	123 E MAIN ST 	SOLON 	52333

dim

dim is a function that allows us to return or set the dimension of an object. We read the output/input of dim as [rows, columns].

Examples

Using the Iowa liquor sales file, what is the dimension of the data set?

Click to see solution 
library(data.table)
options(repr.matrix.max.cols=50)

iowa_full <- fread("/anvil/projects/tdm/data/iowa_liquor_sales/iowa_liquor_sales.csv", select=c("Store Number", "Store Name", "Address", "City", "Zip Code"))

dim(iowa_full)
    27050143
    5

table

table is a function used to build a contingency table, which is a table that shows counts for categorical data, from one or more categories. prop.table is a function that accepts table output, returning proportions of the counts.

Examples

Click to see solution 
library(data.table)
options(repr.matrix.max.cols=50)

iowa_full <- fread("/anvil/projects/tdm/data/iowa_liquor_sales/iowa_liquor_sales.csv", select=c("Store Number", "Store Name", "Address", "City", "Zip Code"))

store_num_freq <- table(iowa_full$`Store Number`)
head(sort(store_num_freq, decreasing=TRUE), 10)
  2633   4829   2190   2512   2572   2603   2515   2614   2647   2648
223447 190702 173109 147581 142536 140319 133959 132915 132269 128608
Click to see solution 
library(data.table)
options(repr.matrix.max.cols=50)

iowa_full <- fread("/anvil/projects/tdm/data/iowa_liquor_sales/iowa_liquor_sales.csv", select=c("Store Number", "Store Name", "Address", "City", "Zip Code"))

store_name_freq <- table(iowa_full$`Store Name`)
head(sort(store_name_freq, decreasing=TRUE), 10)
        HY-VEE #3 / BDI / DES MOINES                       CENTRAL CITY 2
                              223447                               190653
           CENTRAL CITY LIQUOR, INC.      HY-VEE FOOD STORE / CEDAR FALLS
                              173158                               142536
 HY-VEE WINE AND SPIRITS / IOWA CITY HY-VEE WINE AND SPIRITS / BETTENDORF
                              141557                               140319
            HY-VEE #7 / CEDAR RAPIDS                      HY-VEE #4 / WDM
                              131294                               128608
   HY-VEE FOOD STORE #1 / MASON CITY                    BENZ DISTRIBUTING
                              127264                               120357
Click to see solution 
library(data.table)
options(repr.matrix.max.cols=50)

iowa_full <- fread("/anvil/projects/tdm/data/iowa_liquor_sales/iowa_liquor_sales.csv", select=c("Store Number", "Store Name", "Address", "City", "Zip Code"))

store_location_freq <- table(paste(iowa_full$Address, iowa_full$City, iowa_full$`Zip Code`, sep="| "))
head(sort(store_location_freq, decreasing=TRUE), 10)
      3221 SE 14TH ST| DES MOINES| 50320
                                  223447
    1501 MICHIGAN AVE| DES MOINES| 50314
                                  190702
         1460 2ND AVE| DES MOINES| 50314
                                  173109
    1720 WATERFRONT DR| IOWA CITY| 52240
                                  147581
     6301 UNIVERSITY| CEDAR FALLS| 50613
                                  142536
2890 DEVILS GLEN ROAD| BETTENDORF| 52722
                                  140319
       2400 4TH ST SW| MASON CITY| 50401
                                  133959
    1823 E KIMBERLY RD| DAVENPORT| 52807
                                  132915
   5050 EDGEWOOD RD| CEDAR RAPIDS| 52411
                                  132269
   555 S 51ST ST| WEST DES MOINES| 50265
                                  128608