tidyr :: spread（）具有多个键和值 [英] tidyr::spread() with multiple keys and values

问题描述

我假设已经多次询问了这个问题，但是我找不到合适的词来找到可行的解决方案。

I assume this has been asked multiple times but I couldn't find the proper words to find a workable solution.

我如何 Spread（）一个基于多个键的多个值的数据帧？

How can I spread() a data frame based on multiple keys for multiple values?

一个简化的例子（我有更多的列可以展开，但是仅两个键：给定度量的 Id 和 time 点）我正在使用的数据如下所示：

A simplified (I have many more columns to spread, but on only two keys: Id and time point of a given measurement) data I'm working with looks like this:

df <- data.frame(id = rep(seq(1:10),3), 
                 time = rep(1:3, each=10), 
                 x = rnorm(n=30), 
                 y = rnorm(n=30))

> head(df)
  id time           x           y
1  1    1 -2.62671241  0.01669755
2  2    1 -1.69862885  0.24992634
3  3    1  1.01820778 -1.04754037
4  4    1  0.97561596  0.35216040
5  5    1  0.60367158 -0.78066767
6  6    1 -0.03761868  1.08173157
> tail(df)
   id time           x          y
25  5    3  0.03621258 -1.1134368
26  6    3 -0.25900538  1.6009824
27  7    3  0.13996626  0.1359013
28  8    3 -0.60364935  1.5750232
29  9    3  0.89618748  0.0294315
30 10    3  0.14709567  0.5461084

我要做什么d希望拥有一个填充如下的数据框：

What i'd like to have is a dataframe populated like this:

每个 Id 列中的每一行，分别表示时间中的每个值和每个测量变量。

One row per Id columns for each value from the time and each measurement variable.

推荐答案

使用$ dcast 最好使用多个值变量进行重塑或 reshape 从 base R 开始。

Reshaping with multiple value variables can best be done with dcast from data.table or reshape from base R.

library(data.table)
out <- dcast(setDT(df), id ~ paste0("time", time), value.var = c("x", "y"), sep = "")
out
#    id     xtime1     xtime2      xtime3      ytime1      ytime2      ytime3
# 1:  1  0.4334921 -0.5205570 -1.44364515  0.49288757 -1.26955148 -0.83344256
# 2:  2  0.4785870  0.9261711  0.68173681  1.24639813  0.91805332  0.34346260
# 3:  3 -1.2067665  1.7309593  0.04923993  1.28184341 -0.69435556  0.01609261
# 4:  4  0.5240518  0.7481787  0.07966677 -1.36408357  1.72636849 -0.45827205
# 5:  5  0.3733316 -0.3689391 -0.11879819 -0.03276689  0.91824437  2.18084692
# 6:  6  0.2363018 -0.2358572  0.73389984 -1.10946940 -1.05379502 -0.82691626
# 7:  7 -1.4979165  0.9026397  0.84666801  1.02138768 -0.01072588  0.08925716
# 8:  8  0.3428946 -0.2235349 -1.21684977  0.40549497  0.68937085 -0.15793111
# 9:  9 -1.1304688 -0.3901419 -0.10722222 -0.54206830  0.34134397  0.48504564
#10: 10 -0.5275251 -1.1328937 -0.68059800  1.38790593  0.93199593 -1.77498807

---

使用重塑我们可以做

# setDF(df) # in case df is a data.table now
reshape(df, idvar = "id", timevar = "time", direction = "wide")

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