r - 为每个连续序列创建一个组号

Question

我有下面的数据框。我想添加一个“g”列，根据 h_no 列中的连续序列对数据进行分类。即 h_no 1, 2, 3, 4 的第一个序列为组 1，h_no 的第二个序列(1 到 7)为组 2，以此类推，如最后一列“g”所示。

h_no   h_freq    h_freqsq g
1     0.09091 0.008264628 1
2     0.00000 0.000000000 1
3     0.04545 0.002065702 1
4     0.00000 0.000000000 1  
1     0.13636 0.018594050 2
2     0.00000 0.000000000 2
3     0.00000 0.000000000 2
4     0.04545 0.002065702 2
5     0.31818 0.101238512 2
6     0.00000 0.000000000 2
7     0.50000 0.250000000 2 
1     0.13636 0.018594050 3 
2     0.09091 0.008264628 3
3     0.40909 0.167354628 3
4     0.04545 0.002065702 3

Answer 1

您可以使用各种技术向数据添加列。下面的引用来自相关帮助文本的“详细信息”部分，[[.data.frame。

Data frames can be indexed in several modes. When [ and [[ are used with a single vector index (x[i] or x[[i]]), they index the data frame as if it were a list.

my.dataframe["new.col"] <- a.vector
my.dataframe[["new.col"]] <- a.vector

The data.frame method for $, treats x as a list

my.dataframe$new.col <- a.vector

When [ and [[ are used with two indices (x[i, j] and x[[i, j]]) they act like indexing a matrix

my.dataframe[ , "new.col"] <- a.vector

由于 data.frame 的方法假设如果您没有指定您正在使用列还是行，它将假定您指的是列。

<小时/>

对于您的示例，这应该有效:

# make some fake data
your.df <- data.frame(no = c(1:4, 1:7, 1:5), h_freq = runif(16), h_freqsq = runif(16))

# find where one appears and 
from <- which(your.df$no == 1)
to <- c((from-1)[-1], nrow(your.df)) # up to which point the sequence runs

# generate a sequence (len) and based on its length, repeat a consecutive number len times
get.seq <- mapply(from, to, 1:length(from), FUN = function(x, y, z) {
            len <- length(seq(from = x[1], to = y[1]))
            return(rep(z, times = len))
         })

# when we unlist, we get a vector
your.df$group <- unlist(get.seq)
# and append it to your original data.frame. since this is
# designating a group, it makes sense to make it a factor
your.df$group <- as.factor(your.df$group)


   no     h_freq   h_freqsq group
1   1 0.40998238 0.06463876     1
2   2 0.98086928 0.33093795     1
3   3 0.28908651 0.74077119     1
4   4 0.10476768 0.56784786     1
5   1 0.75478995 0.60479945     2
6   2 0.26974011 0.95231761     2
7   3 0.53676266 0.74370154     2
8   4 0.99784066 0.37499294     2
9   5 0.89771767 0.83467805     2
10  6 0.05363139 0.32066178     2
11  7 0.71741529 0.84572717     2
12  1 0.10654430 0.32917711     3
13  2 0.41971959 0.87155514     3
14  3 0.32432646 0.65789294     3
15  4 0.77896780 0.27599187     3
16  5 0.06100008 0.55399326     3