r - R markdown 中的 reshape 问题

Question

我想创建一个长到宽格式的数据集。当我在 R 控制台运行这个程序时，它会给出输出。但它在 R markdown 中不起作用。

   library(gapminder)
   library(dplyr)
   library(knitr)
   dat <- gapminder%>%
  group_by(continent,year) %>%
  summarize(mean = mean(lifeExp))
  dat1 <- as.data.frame(dat)
   res <- reshape( dat1 , timevar ="continent" , idvar ="year",  direction = 
  "wide" , v.names="mean")
    kable(res)

但是当我在 R markdown 运行此程序时，它显示错误消息:[.data.frame(data, , timevar) 中的错误:选择了未定义的列 调用: ... reshape -> reshapeWide -> unique -> [ -> [.data.frame 执行停止

Answer 1

它通过以下简单的调用对我有用:

---
title: "Untitled"
author: "Me"
date: "2/14/2018"
output: html_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```

## Long to wide

Example 
```{r}

library(gapminder)
   library(dplyr)
   library(knitr)
   dat <- gapminder%>%
  group_by(continent,year) %>%
  summarize(mean = mean(lifeExp))
  dat1 <- as.data.frame(dat)
   res <- reshape( dat1 , timevar ="continent" , idvar ="year",  direction = 
  "wide" , v.names="mean")
    kable(res)


```