從不同表中合併數據

Question

我有兩個不同的表，如下所示（第一個表具有部分信息，第二個表具有崩潰信息。第一個表具有所有部分信息，一些部分沒有任何崩潰發生。其中有在第二個表中的部分沒有崩潰信息所需的合併表計算總崩潰，如果沒有崩潰，但是該節將需要在零個值插）：

a <- structure(list(CSECT = c("001-01", "001-01", "001-01", "001-04", "001-01", "001-01", "001-02", "001-02", "001-03", "001-04"), 
From = c("0", "1", "3", "4", "5", "7", "8", "1", "2.2", "3.4"), 
To = c("1", "3", "4", "5", "6", "8", "9", "2.2", "3.4", "4.5")), 
.Names = c("CSECT", "From", "To"), row.names = c(NA, -10L), class = "data.frame") 
a 

    CSECT From To 
1 001-01 0 1 
2 001-01 1 3 
3 001-01 3 4 
4 001-04 4 5 
5 001-01 5 6 
6 001-01 7 8 
7 001-02 8 9 
8 001-02 1 2.2 
9 001-03 2.2 3.4 
10 001-04 3.4 4.5 

b <- structure(list(CSECT = c("001-01", "001-01", "001-01", "001-01", "001-01", "001-01", "001-01", "001-01", "001-01", "001-01", 
"001-02", "001-02","001-02","001-02","001-02","001-02","001-02"), 
From = c("0", "0", "0", "0", "1", "1", "3", "3", "3", "3", "8", "8", "8", "8","1", "1", "1"), 
To = c("1", "1", "1", "1", "3", "3", "4", "4", "4", "4", "9", "9", "9", "9", "2.2", "2.2", "2.2"), 
CrashID = c("3409", "3410", "6790", "1100", "1200", "5609", "6730", "1220", "1234", "1239", 
"4409", "5610", "6794", "1123", "1245", "5634", "6732")), 
.Names = c("CSECT", "From", "To", "CrashID"), row.names = c(NA, -17L), class = "data.frame") 
b 

    CSECT From To CrashID 
1 001-01 0 1 3409 
2 001-01 0 1 3410 
3 001-01 0 1 6790 
4 001-01 0 1 1100 
5 001-01 1 3 1200 
6 001-01 1 3 5609 
7 001-01 3 4 6730 
8 001-01 3 4 1220 
9 001-01 3 4 1234 
10 001-01 3 4 1239 
11 001-02 8 9 4409 
12 001-02 8 9 5610 
13 001-02 8 9 6794 
14 001-02 8 9 1123 
15 001-02 1 2.2 1245 
16 001-02 1 2.2 5634 
17 001-02 1 2.2 6732 

我喜歡合併如下數據：

CSECT From To Count 
001-01 0  1  4 
001-01 1  3  2 
001-01 3  4  4 
001-04 4  5  0 
001-01 5  6  0 
001-01 7  8  0 
001-02 8  9  4 
001-02 1  2.2  3 
001-03 2.2  3.4  0 
001-04 3.4  4.5  0 

提前致謝。

Answer 1

cc <- by(b[-(1:3)], b[1:3], function(x) list( 
    Total =length(x$CrashID), 
    Fatal =sum(x$Severity=="Fatal"), 
    Severe=sum(x$Severity=="Severe"), 
    PDO=sum(x$Severity=="PDO")) , 
    simplify=FALSE) 
dd <- cbind(unique(b[1:3]), do.call(rbind, cc)) 
ee < -merge(a, dd, all.x=TRUE) 
ee[ is.na(ee) ] <- 0 
ee 
#----------- 

    CSECT From To AADT Total Fatal Severe PDO 
1 001-01 0 1 1100  4  1  0 3 
2 001-01 1 3 1200  3  0  0 3 
3 001-01 3 4 890  2  0  0 2 
4 001-01 5 6 2000  0  0  0 0 
5 001-01 7 8 5000  0  0  0 0 
6 001-02 1 2.2 2000  4  0  0 4 
7 001-02 8 9 6700  4  1  1 2 
8 001-03 2.2 3.4 3000  0  0  0 0 
9 001-04 3.4 4.5 1230  0  0  0 0 
10 001-04 4 5 1000  0  0  0 0