在 R 中，如何在字符串表中搜索特定模式

Question

      V1  V2       V3     V4  V5     V6     V7  V8    V9    V10 V11   V12    V13 V14   V15 V16 V17
1       1  1  round-0  10523 180 yellow     NA  NA           NA  NA           NA  NA        NA  NA
2   11973  1  round-1  19478 150 yellow     NA  NA           NA  NA           NA  NA        NA  NA
3   22428  1  round-2  28928 130 yellow  29928 150 brake  31433 160   red     NA  NA        NA  NA
4   39333  1  round-3  47333 160 yellow  48588 185   red     NA  NA           NA  NA        NA  NA
5   49788  1  round-4  56288 130 yellow  58038 165 brake  59038 175   red     NA  NA        NA  NA
6   64688  1  round-5  71693 140 yellow  74293 192   red  74393 194 crash     NA  NA        NA  NA
7   85148  1  round-6  91648 130 yellow  94648 190   red     NA  NA           NA  NA        NA  NA
8   95598  1  round-7 103653 130 yellow 104903 155 brake 105403 165   red     NA  NA        NA  NA
9  112703  1  round-8 122758 130 yellow 125758 190   red 125758 190 crash     NA  NA        NA  NA
10 136513  1  round-9 146563 130 yellow 147963 158 brake 148063 160   red     NA  NA        NA  NA
11 157118  1 round-10 164618 150 yellow 167118 200   red     NA  NA           NA  NA        NA  NA
12 167568  1 round-11 179123 120 yellow 182023 178   red 182373 185 brake 182623 190 crash  NA  NA
13 193378  1 round-12 200378 140 yellow 201878 170   red 203278 198 crash     NA  NA        NA  NA

所以我在 csv 中有一個表，用 read.table 導入，看起來像上面那樣。 如您所見，數據甚至不在每一行中。 它是三元組的形式，V3 V6等等存儲字符串，它們對應前面兩個單元格中存儲的數字

所以一直困擾着我的是，我似乎無法弄清楚如何編寫一個計數來計算表中模式的數量。 我的任務是統計右剎出現碰撞的次數。 我知道我可以像嵌套 ifelse 一樣使用，就像我在存儲剎車前找出兩個單元格的數字時所做的那樣：

df$brake <- ifelse(df$V9 == "brake", df$V7,
                   ifelse(df$V12 == "brake", df$V10,
                          ifelse(df$V15 == "brake", df$V13,
                                 ifelse(df$V18 == "brake", df$V16,
                                        ifelse(df$V21 == "brake", df$V19, 
                                               ifelse(df$V24 == "brake", df$V22, 
                                                      ifelse(df$V27 == "brake", df$V25, NA)))))))

，但我有 35 列，我只是想知道是否有更精簡的方法來做到這一點。 任何幫助將不勝感激 ：）

編輯：對不起，不清楚。 我遇到的主要問題是如何計算剎車后發生碰撞的頻率。 （我添加了用於提取剎車前 2 個單元格的數值的代碼，因為我認為兩者的解決方案是相似的：基本上，一個是在任何剎車崩潰后查看 3 個單元格，另一個是提取值 2剎車前的單元格。抱歉造成混亂）

Answer 1

根據顯示的代碼，我假設“brake”列是 9、12、15 等。因此，我們創建一個數字索引 (“indx”) 來提取這些列。 還為“剎車”列（“indx1”）創建了一個邏輯矩陣。 然后，我們可以創建行索引（ 1:nrow(df) ）和列索引（ max.col(indx1, 'first') ）， cbind其cbind並提取屬於7, 10, 13, etc.列的元素7, 10, 13, etc. 。 我們將元素更改為NA對應於 'indx1' 中為 rowSums 為 '0' 的rowSums

indx <- seq(9,ncol(df), by=3)
indx1 <- df[indx]=='brake'
df$brake <- df[indx-2][cbind(1:nrow(df), max.col(indx1, 'first'))]* 
                    NA^!rowSums(indx1)
 df$brake
 #[1]     NA     NA  29928     NA  58038     NA     NA 104903     NA 147963
 #[11]     NA 182373     NA

數據

 df <- structure(list(V1 = c(1L, 11973L, 22428L, 39333L, 49788L, 64688L, 
85148L, 95598L, 112703L, 136513L, 157118L, 167568L, 193378L), 
    V2 = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L
    ), V3 = c("round-0", "round-1", "round-2", "round-3", "round-4", 
    "round-5", "round-6", "round-7", "round-8", "round-9", "round-10", 
    "round-11", "round-12"), V4 = c(10523L, 19478L, 28928L, 47333L, 
    56288L, 71693L, 91648L, 103653L, 122758L, 146563L, 164618L, 
    179123L, 200378L), V5 = c(180L, 150L, 130L, 160L, 130L, 140L, 
    130L, 130L, 130L, 130L, 150L, 120L, 140L), V6 = c("yellow", 
    "yellow", "yellow", "yellow", "yellow", "yellow", "yellow", 
    "yellow", "yellow", "yellow", "yellow", "yellow", "yellow"
    ), V7 = c(NA, NA, 29928L, 48588L, 58038L, 74293L, 94648L, 
    104903L, 125758L, 147963L, 167118L, 182023L, 201878L), V8 = c(NA, 
    NA, 150L, 185L, 165L, 192L, 190L, 155L, 190L, 158L, 200L, 
    178L, 170L), V9 = c("", "", "brake", "red", "brake", "red", 
    "red", "brake", "red", "brake", "red", "red", "red"), V10 = c(NA, 
    NA, 31433L, NA, 59038L, 74393L, NA, 105403L, 125758L, 148063L, 
    NA, 182373L, 203278L), V11 = c(NA, NA, 160L, NA, 175L, 194L, 
    NA, 165L, 190L, 160L, NA, 185L, 198L), V12 = c("", "", "red", 
    "", "red", "crash", "", "red", "crash", "red", "", "brake", 
    "crash"), V13 = c(NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 
    NA, 182623L, NA), V14 = c(NA, NA, NA, NA, NA, NA, NA, NA, 
    NA, NA, NA, 190L, NA), V15 = c("", "", "", "", "", "", "", 
    "", "", "", "", "crash", ""), V16 = c(NA, NA, NA, NA, NA, 
    NA, NA, NA, NA, NA, NA, NA, NA), V17 = c(NA, NA, NA, NA, 
    NA, NA, NA, NA, NA, NA, NA, NA, NA)), .Names = c("V1", "V2", 
"V3", "V4", "V5", "V6", "V7", "V8", "V9", "V10", "V11", "V12", 
"V13", "V14", "V15", "V16", "V17"), class = "data.frame", row.names = c("1", 
"2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13"
))