R語言列表和數據框的具體使用

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1.列表

列表“list”是一種比較的特別的對象集合，不同的序號對於不同的元素，當然元素的也可以是不同類型的，那麼我們用R語言先簡單來構造一個列表。

1.1創建

> a<-c(1:20)
> b<-matrix(1:20,4,5)
> mlist<-list(a,b)
> mlist
[[1]]
 [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14
[15] 15 16 17 18 19 20
 
[[2]]
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    5    9   13   17
[2,]    2    6   10   14   18
[3,]    3    7   11   15   19
[4,]    4    8   12   16   20

1.2 訪問

1.2.1 下標訪問

> mlist[1]
[[1]]
 [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14
[15] 15 16 17 18 19 20
 
> mlist[2]
[[1]]
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    5    9   13   17
[2,]    2    6   10   14   18
[3,]    3    7   11   15   19
[4,]    4    8   12   16   20

1.2.2 名稱訪問 

> state.center["x"]
$x
 [1]  -86.7509 -127.2500 -111.6250  -92.2992
 [5] -119.7730 -105.5130  -72.3573  -74.9841
 [9]  -81.6850  -83.3736 -126.2500 -113.9300
[13]  -89.3776  -86.0808  -93.3714  -98.1156
[17]  -84.7674  -92.2724  -68.9801  -76.6459
[21]  -71.5800  -84.6870  -94.6043  -89.8065
[25]  -92.5137 -109.3200  -99.5898 -116.8510
[29]  -71.3924  -74.2336 -105.9420  -75.1449
[33]  -78.4686 -100.0990  -82.5963  -97.1239
[37] -120.0680  -77.4500  -71.1244  -80.5056
[41]  -99.7238  -86.4560  -98.7857 -111.3300
[45]  -72.5450  -78.2005 -119.7460  -80.6665
[49]  -89.9941 -107.2560

1.2.3 符號訪問

> state.center$x
 [1]  -86.7509 -127.2500 -111.6250  -92.2992
 [5] -119.7730 -105.5130  -72.3573  -74.9841
 [9]  -81.6850  -83.3736 -126.2500 -113.9300
[13]  -89.3776  -86.0808  -93.3714  -98.1156
[17]  -84.7674  -92.2724  -68.9801  -76.6459
[21]  -71.5800  -84.6870  -94.6043  -89.8065
[25]  -92.5137 -109.3200  -99.5898 -116.8510
[29]  -71.3924  -74.2336 -105.9420  -75.1449
[33]  -78.4686 -100.0990  -82.5963  -97.1239
[37] -120.0680  -77.4500  -71.1244  -80.5056
[41]  -99.7238  -86.4560  -98.7857 -111.3300
[45]  -72.5450  -78.2005 -119.7460  -80.6665
[49]  -89.9941 -107.2560

 1.3 註意

一個中括號和兩個中括號的區別

一個中括號輸出的是列表的一個子列表，兩個中括號輸出的是列表的元素

> class(mlist[1])
[1] "list"
> class(mlist[[1]])
[1] "integer"

 我們添加元素時要註意用兩個中括號

2.數據框

數據框是R種的一個數據結構，他通常是矩陣形式的數據，但矩陣各列可以是不同類型的，數據框每列是一個變量，沒行是一個觀測值。

但是，數據框又是一種特殊的列表對象，其class屬性為“data.frame”，各列表成員必須是向量（數值型、字符型、邏輯型）、因子、數值型矩陣、列表或者其它數據框。向量、因子成員為數據框提供一個變量，如果向量非數值型會被強型轉換為因子。而矩陣、列表、數據框等必須和數據框具有相同的行數。

2.1 創建

> state<-data.frame(state.name,state.abb,state.area)
> state
       state.name state.abb state.area
1         Alabama        AL      51609
2          Alaska        AK     589757
3         Arizona        AZ     113909
4        Arkansas        AR      53104
5      California        CA     158693
6        Colorado        CO     104247
7     Connecticut        CT       5009
8        Delaware        DE       2057
9         Florida        FL      58560
10        Georgia        GA      58876
11         Hawaii        HI       6450
12          Idaho        ID      83557
13       Illinois        IL      56400
14        Indiana        IN      36291
15           Iowa        IA      56290
16         Kansas        KS      82264
17       Kentucky        KY      40395
18      Louisiana        LA      48523
19          Maine        ME      33215
20       Maryland        MD      10577
21  Massachusetts        MA       8257
22       Michigan        MI      58216
23      Minnesota        MN      84068
24    Mississippi        MS      47716
25       Missouri        MO      69686
26        Montana        MT     147138
27       Nebraska        NE      77227
28         Nevada        NV     110540
29  New Hampshire        NH       9304
30     New Jersey        NJ       7836
31     New Mexico        NM     121666
32       New York        NY      49576
33 North Carolina        NC      52586
34   North Dakota        ND      70665
35           Ohio        OH      41222
36       Oklahoma        OK      69919
37         Oregon        OR      96981
38   Pennsylvania        PA      45333
39   Rhode Island        RI       1214
40 South Carolina        SC      31055
41   South Dakota        SD      77047
42      Tennessee        TN      42244
43          Texas        TX     267339
44           Utah        UT      84916
45        Vermont        VT       9609
46       Virginia        VA      40815
47     Washington        WA      68192
48  West Virginia        WV      24181
49      Wisconsin        WI      56154
50        Wyoming        WY      97914
> 

2.2 訪問

2.2.1 下標訪問

> state[1]
       state.name
1         Alabama
2          Alaska
3         Arizona
4        Arkansas
5      California
6        Colorado
7     Connecticut
8        Delaware
9         Florida
10        Georgia
11         Hawaii
12          Idaho
13       Illinois
14        Indiana
15           Iowa
16         Kansas
17       Kentucky
18      Louisiana
19          Maine
20       Maryland
21  Massachusetts
22       Michigan
23      Minnesota
24    Mississippi
25       Missouri
26        Montana
27       Nebraska
28         Nevada
29  New Hampshire
30     New Jersey
31     New Mexico
32       New York
33 North Carolina
34   North Dakota
35           Ohio
36       Oklahoma
37         Oregon
38   Pennsylvania
39   Rhode Island
40 South Carolina
41   South Dakota
42      Tennessee
43          Texas
44           Utah
45        Vermont
46       Virginia
47     Washington
48  West Virginia
49      Wisconsin
50        Wyoming

2.2.2 名稱訪問

> state["state.name"]
       state.name
1         Alabama
2          Alaska
3         Arizona
4        Arkansas
5      California
6        Colorado
7     Connecticut
8        Delaware
9         Florida
10        Georgia
11         Hawaii
12          Idaho
13       Illinois
14        Indiana
15           Iowa
16         Kansas
17       Kentucky
18      Louisiana
19          Maine
20       Maryland
21  Massachusetts
22       Michigan
23      Minnesota
24    Mississippi
25       Missouri
26        Montana
27       Nebraska
28         Nevada
29  New Hampshire
30     New Jersey
31     New Mexico
32       New York
33 North Carolina
34   North Dakota
35           Ohio
36       Oklahoma
37         Oregon
38   Pennsylvania
39   Rhode Island
40 South Carolina
41   South Dakota
42      Tennessee
43          Texas
44           Utah
45        Vermont
46       Virginia
47     Washington
48  West Virginia
49      Wisconsin
50        Wyoming

2.2.3 符號訪問

> state$state.name
 [1] "Alabama"        "Alaska"        
 [3] "Arizona"        "Arkansas"      
 [5] "California"     "Colorado"      
 [7] "Connecticut"    "Delaware"      
 [9] "Florida"        "Georgia"       
[11] "Hawaii"         "Idaho"         
[13] "Illinois"       "Indiana"       
[15] "Iowa"           "Kansas"        
[17] "Kentucky"       "Louisiana"     
[19] "Maine"          "Maryland"      
[21] "Massachusetts"  "Michigan"      
[23] "Minnesota"      "Mississippi"   
[25] "Missouri"       "Montana"       
[27] "Nebraska"       "Nevada"        
[29] "New Hampshire"  "New Jersey"    
[31] "New Mexico"     "New York"      
[33] "North Carolina" "North Dakota"  
[35] "Ohio"           "Oklahoma"      
[37] "Oregon"         "Pennsylvania"  
[39] "Rhode Island"   "South Carolina"
[41] "South Dakota"   "Tennessee"     
[43] "Texas"          "Utah"          
[45] "Vermont"        "Virginia"      
[47] "Washington"     "West Virginia" 
[49] "Wisconsin"      "Wyoming"

2.2.4 函數訪問

> attach(state)
The following objects are masked from package:datasets:

2.2.4 函數訪問

> attach(state)
The following objects are masked from package:datasets:
 
    state.abb, state.area, state.name
 
> state.name
 [1] "Alabama"        "Alaska"        
 [3] "Arizona"        "Arkansas"      
 [5] "California"     "Colorado"      
 [7] "Connecticut"    "Delaware"      
 [9] "Florida"        "Georgia"       
[11] "Hawaii"         "Idaho"         
[13] "Illinois"       "Indiana"       
[15] "Iowa"           "Kansas"        
[17] "Kentucky"       "Louisiana"     
[19] "Maine"          "Maryland"      
[21] "Massachusetts"  "Michigan"      
[23] "Minnesota"      "Mississippi"   
[25] "Missouri"       "Montana"       
[27] "Nebraska"       "Nevada"        
[29] "New Hampshire"  "New Jersey"    
[31] "New Mexico"     "New York"      
[33] "North Carolina" "North Dakota"  
[35] "Ohio"           "Oklahoma"      
[37] "Oregon"         "Pennsylvania"  
[39] "Rhode Island"   "South Carolina"
[41] "South Dakota"   "Tennessee"     
[43] "Texas"          "Utah"          
[45] "Vermont"        "Virginia"      
[47] "Washington"     "West Virginia" 
[49] "Wisconsin"      "Wyoming"

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