将数据从长格式重新格式化为宽格式 [英] Reformat data from long to wide

问题描述

如何将此数据重新格式化为宽格式?

How can I reformat this data to a wide format?

species val    price
setosa  5.1     3
setosa  4.9     3
setosa  4.7     3
setosa  4.6     2

所需的输出:

species val1 val2 val3 val4 price1 price2 price3 price4
setosa  5.1  4.9  4.7  4.6    3       3      3      2

我曾尝试从 tidyr 传播但没有成功.

I have tried spread from tidyr but without success.

推荐答案

data.table v 1.9.6+ 允许你传递多个 value.vars，所以你可以简单地做

data.table v 1.9.6+ allows you to pass more than one value.vars, so you can simply do

library(data.table)
dcast(setDT(df), species ~ val + price, value.var = c("val", "price"))
#    species val.1_4.6_2 val.1_4.7_3 val.1_4.9_3 val.1_5.1_3 price.1_4.6_2 price.1_4.7_3 price.1_4.9_3 price.1_5.1_3
# 1:  setosa         4.6         4.7         4.9         5.1             2             3             3             3

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