Data Frame

Create a data frame

x=1:26;
z=letters;
y=paste(z, x, sep=":");
d=data.frame(C1=x, C2=y, C3=z);
d;

##    C1   C2 C3
## 1   1  a:1  a
## 2   2  b:2  b
## 3   3  c:3  c
## 4   4  d:4  d
## 5   5  e:5  e
## 6   6  f:6  f
## 7   7  g:7  g
## 8   8  h:8  h
## 9   9  i:9  i
## 10 10 j:10  j
## 11 11 k:11  k
## 12 12 l:12  l
## 13 13 m:13  m
## 14 14 n:14  n
## 15 15 o:15  o
## 16 16 p:16  p
## 17 17 q:17  q
## 18 18 r:18  r
## 19 19 s:19  s
## 20 20 t:20  t
## 21 21 u:21  u
## 22 22 v:22  v
## 23 23 w:23  w
## 24 24 x:24  x
## 25 25 y:25  y
## 26 26 z:26  z

str(d);

## 'data.frame':    26 obs. of  3 variables:
##  $ C1: int  1 2 3 4 5 6 7 8 9 10 ...
##  $ C2: Factor w/ 26 levels "a:1","b:2","c:3",..: 1 2 3 4 5 6 7 8 9 10 ...
##  $ C3: Factor w/ 26 levels "a","b","c","d",..: 1 2 3 4 5 6 7 8 9 10 ...

colnames(d);

## [1] "C1" "C2" "C3"

rownames(d);

##  [1] "1"  "2"  "3"  "4"  "5"  "6"  "7"  "8"  "9"  "10" "11" "12" "13" "14"
## [15] "15" "16" "17" "18" "19" "20" "21" "22" "23" "24" "25" "26"

dim(d);

## [1] 26  3

# edit(d);

Fetch values from a data frame

d;

##    C1   C2 C3
## 1   1  a:1  a
## 2   2  b:2  b
## 3   3  c:3  c
## 4   4  d:4  d
## 5   5  e:5  e
## 6   6  f:6  f
## 7   7  g:7  g
## 8   8  h:8  h
## 9   9  i:9  i
## 10 10 j:10  j
## 11 11 k:11  k
## 12 12 l:12  l
## 13 13 m:13  m
## 14 14 n:14  n
## 15 15 o:15  o
## 16 16 p:16  p
## 17 17 q:17  q
## 18 18 r:18  r
## 19 19 s:19  s
## 20 20 t:20  t
## 21 21 u:21  u
## 22 22 v:22  v
## 23 23 w:23  w
## 24 24 x:24  x
## 25 25 y:25  y
## 26 26 z:26  z

d[,1];

##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
## [24] 24 25 26

d$C1;

##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
## [24] 24 25 26

d[3,];

##   C1  C2 C3
## 3  3 c:3  c

d[3,1];

## [1] 3

d$C1[3];

## [1] 3

Insert column to data frame

d;

##    C1   C2 C3
## 1   1  a:1  a
## 2   2  b:2  b
## 3   3  c:3  c
## 4   4  d:4  d
## 5   5  e:5  e
## 6   6  f:6  f
## 7   7  g:7  g
## 8   8  h:8  h
## 9   9  i:9  i
## 10 10 j:10  j
## 11 11 k:11  k
## 12 12 l:12  l
## 13 13 m:13  m
## 14 14 n:14  n
## 15 15 o:15  o
## 16 16 p:16  p
## 17 17 q:17  q
## 18 18 r:18  r
## 19 19 s:19  s
## 20 20 t:20  t
## 21 21 u:21  u
## 22 22 v:22  v
## 23 23 w:23  w
## 24 24 x:24  x
## 25 25 y:25  y
## 26 26 z:26  z

d$C5=1;
# d$C6=1:100; #Error
d$C6=seq(3, 8, length=26);

Delete column or row from data frame

d$C5=NULL;
head(d);

##   C1  C2 C3  C6
## 1  1 a:1  a 3.0
## 2  2 b:2  b 3.2
## 3  3 c:3  c 3.4
## 4  4 d:4  d 3.6
## 5  5 e:5  e 3.8
## 6  6 f:6  f 4.0

Check for data frame

is.data.frame(d);

## [1] TRUE

Task: Now Go to Task page and finish Data Frame