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103.1.5 R Data Frames

A type of Datatype

In previous section, we studied about R Data Types, now we will be studying about R Data Frames.

A data frame is a common way for storing data in R. We can create data frames using function data.frame

Here are four vectors of the same length,

  >Name<-c("Rick","Nick","Harry")
  >Age<-c(15,17,19)
  >English<-c(12,13,20)
  >Maths<-c(20,23,21)

A data frame, students has been created using the individual vectors Name, Age, English, and Maths.

 >students<-data.frame(Name,Age,English,Maths)
 >students 
   Name Age English Maths
     1 Rick 15 12 20
     2 Nick 17 13 23
     3 Harry 19 20 21
 >Profile_data <- data.frame(Name, Age)
 >Profile_data 
   Name Age
  1 Rick 15
  2 Nick 17
  3 Harry 19

 >students1 <-c(Name, Age, English, Maths)
 >students1
 [1] "Rick" "Nick" "Harry" "15" "17" "19" "12" "13" "20" "20" "23" 
 [12] "21"


Accessing a Data Frame

To access each column of a data frame, we use ‘$’. We write it as- Dataset$column

 students$Name

 [1] Rick Nick Harry
 Levels: Harry Nick Rick

We have other ways-

 >students$English
 [1] 12 13 20
 >students["Name"]
  Name
 1 Rick
 2 Nick
 3 Harry

>students[1,]
 Name Age English Maths
 1 Rick 15 12 20
 >students[,1]
 [1] Rick Nick Harry
 Levels: Harry Nick Rick
 >students[,2:4] 
 Age English Maths
  1 15 12 20
  2 17 13 23
  3 19 20 21
 >students[,-1]
 Age English Maths
 1 15 12 20
 2 17 13 23
 3 19 20 21
 >students[-1,]
 Name Age English Maths
 2 Nick 17 13 23
 3 Harry 19 20 21
 >students[,c(1,4)] 
  Name Maths
 1 Rick 20
 2 Nick 23
 3 Harry 21

There is a slight Difference in Accessed Data frame elements in these commands.

 >students$Name
 [1] Rick Nick Harry
 Levels: Harry Nick Rick

 

 

 >students["Name"]
  Name
 1 Rick
 2 Nick
 3 Harry

 

 >students[,1]
 [1] Rick Nick Harry
 Levels: Harry Nick Rick

Built-in DataFrames

When we install R, then R comes with built-in Datasets. These are some of the useful open source datasets for practice. We can call them by command: data()

 data()
 #Air Passengers data
 AirPassengers
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
 ## 1949 112 118 132 129 121 135 148 148 136 119 104 118
 ## 1950 115 126 141 135 125 149 170 170 158 133 114 140
 ## 1951 145 150 178 163 172 178 199 199 184 162 146 166
 ## 1952 171 180 193 181 183 218 230 242 209 191 172 194
 ## 1953 196 196 236 235 229 243 264 272 237 211 180 201
 ## 1954 204 188 235 227 234 264 302 293 259 229 203 229
 ## 1955 242 233 267 269 270 315 364 347 312 274 237 278
 ## 1956 284 277 317 313 318 374 413 405 355 306 271 306
 ## 1957 315 301 356 348 355 422 465 467 404 347 305 336
 ## 1958 340 318 362 348 363 435 491 505 404 359 310 337
 ## 1959 360 342 406 396 420 472 548 559 463 407 362 405
 ## 1960 417 391 419 461 472 535 622 606 508 461 390 432

Cars data set is included with car speed and stopping distance.

#cars data
 cars
 ##    speed dist
 ## 1      4    2
 ## 2      4   10
 ## 3      7    4
 ## 4      7   22
 ## 5      8   16
 ## 6      9   10
 ## 7     10   18
 ## 8     10   26
 ## 9     10   34
 ## 10    11   17
 ## 11    11   28
 ## 12    12   14
 ## 13    12   20
 ## 14    12   24
 ## 15    12   28
 ## 16    13   26
 ## 17    13   34
 ## 18    13   34
 ## 19    13   46
 ## 20    14   26
 ## 21    14   36
 ## 22    14   60
 ## 23    14   80
 ## 24    15   20
 ## 25    15   26
 ## 26    15   54
 ## 27    16   32
  ## 28    16   40
  ## 29    17   32
  ## 30    17   40
  ## 31    17   50
  ## 32    18   42
  ## 33    18   56
  ## 34    18   76
  ## 35    18   84
 ## 36    19   36
 ## 37    19   46
 ## 38    19   68
 ## 39    20   32
 ## 40    20   48
 ## 41    20   52
 ## 42    20   56
 ## 43    20   64
 ## 44    22   66
 ## 45    23   54
 ## 46    24   70
 ## 47    24   92
 ## 48    24   93
 ## 49    24  120
 ## 50    25   85

This is about Data Frames. Next you will learn about the R Lists.

 

In next section, we will be studying about R Lists.

6th January 2017

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