我有这个数据框：
> df
Z freq proba
1 17 1 0.0033289263
2 18 4 0.0055569026
3 19 2 0.0087878028
4 20 3 0.0132023556
5 21 16 0.0188900561
6 22 12 0.0257995234
7 23 30 0.0337042731
8 24 41 0.0421963455
9 25 56 0.0507149437
10 26 65 0.0586089198
11 27 65 0.0652230449
12 28 93 0.0699913154
13 29 82 0.0725182432
14 30 94 0.0726318551
15 31 72 0.0703990113
16 32 74 0.0661024717
17 33 58 0.0601873020
18 34 66 0.0531896431
19 35 38 0.0456625487
20 36 45 0.0381117389
21 37 27 0.0309498221
22 38 17 0.0244723502
23 39 15 0.0188543771
24 40 13 0.0141629367
25 41 4 0.0103793600
26 42 1 0.0074254435
27 43 2 0.0051886582
28 45 1 0.0023658767
29 46 1 0.0015453804
30 49 2 0.0003792308
# Here are my datas :
> dput(df)
structure(list(Z = c(17, 18, 19, 20, 21, 22, 23, 24, 25, 26,
27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42,
43, 45, 46, 49), freq = c(1, 4, 2, 3, 16, 12, 30, 41, 56, 65,
65, 93, 82, 94, 72, 74, 58, 66, 38, 45, 27, 17, 15, 13, 4, 1,
2, 1, 1, 2), proba = c(0.0033289262662263, 0.00555690264007235,
0.00878780282243439, 0.0132023555702843, 0.0188900560866825,
0.0257995234198431, 0.0337042730520012, 0.0421963455163949, 0.0507149437492447,
0.0586089198012906, 0.0652230449359029, 0.0699913153996099, 0.0725182432348992,
0.0726318551493006, 0.0703990113442269, 0.0661024716831246, 0.0601873020200862,
0.0531896430528685, 0.045662548708844, 0.0381117389181843, 0.030949822142559,
0.0244723501557229, 0.01885437705459, 0.0141629366839816, 0.0103793599644779,
0.00742544354411115, 0.00518865818999788, 0.00236587669133322,
0.00154538036835848, 0.000379230768851682)), .Names = c("Z",
"freq", "proba"), row.names = c(NA, -30L), class = "data.frame")
我想用下一行重新组合值“ freq”小于5的行，而下一行小于5的行。如果我足够清楚，则为Idk，所以这是我期望的输出：
> df2
labels effectifs pi
1 17;20 10 0.03087599
2 21 16 0.01889006
3 22 12 0.02579952
4 23 30 0.03370427
5 24 41 0.04219635
6 25 56 0.05071494
7 26 65 0.05860892
8 27 65 0.06522304
9 28 93 0.06999132
10 29 82 0.07251824
11 30 94 0.07263186
12 31 72 0.07039901
13 32 74 0.06610247
14 33 58 0.06018730
15 34 66 0.05318964
16 35 38 0.04566255
17 36 45 0.03811174
18 37 27 0.03094982
19 38 17 0.02447235
20 39 15 0.01885438
21 40 13 0.01416294
22 41;49 11 0.02728395
我使用nested做到了while，但是我发现此解决方案非常痛苦且未优化。
i <- 1
freqs <- c()
labels <- c()
pi <- c()
while(i < nrow(df)) {
if (df$freq[i] >= 5) {
freqs <- c(freqs, df$freq[i])
labels <- c(labels, df$Z[i])
pi <- c(pi, df$proba[i])
i <- i + 1
}
else {
count <- df$freq[i]
countPi <- df$proba[i]
k <- i
j <- i
while(df$freq[i] < 5 & i < nrow(df)) {
if (df$freq[i+1] < 5) {
count <- count + df$freq[i+1]
countPi <- countPi + df$proba[i+1]
j <- i + 1
}
i <- i + 1
}
labels <- c(labels, paste0(df$Z[k], ";", df$Z[j]))
freqs <- c(freqs, count)
pi <- c(pi, countPi)
}
}
df2 <- data.frame(labels, freqs, pi)
我敢肯定，也许还有dplyr会更好。如果您有更好的解决方案..谢谢！
引入新功能后，我们可以使用“ data.table”的“ devel”版本rleid。在这里，我们将“ data.frame”转换为“ data.table”（setDT(df)），并使用逻辑索引（freq <5）创建一个分组变量（“ gr”）rleid。“ Z”列是“数字/整数”类。从“ Z”创建一个字符列（“ Z1”）。按“ gr”分组，如果该组中所有元素的“频率”均小于5，则通过对列（.SD[1L]）的首次观察将行汇总为单个行，并删除不需要的列（因为.SD包括“ Z1”（这将导致重复的列），并在其后附加我们粘贴该组的“ Z”min和max值“ Z1”。else .SD否则，请使其保持不变（ ）。通过将其分配给“ NULL”来删除不需要的列。
library(data.table) #data.table_1.9.5
res <- setDT(df)[, gr:=rleid(freq<5)][, Z1:= as.character(Z)][,
if(all(freq<5)) c(.SD[1L][,-4, with=FALSE],
list(Z1=toString(c(min(Z), max(Z)))))
else .SD, gr][,1:2 :=NULL][]
head(res,3)
# freq proba Z1
#1: 1 0.003328926 17, 20
#2: 16 0.018890056 21
#3: 12 0.025799523 22
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