RMarkdown error with melt() function - r

Question

I'm trying to create a file word starting from a program that on console perfectly works.
The problem is that when it reaches a function that uses melt() it generates an error
cannot find melt function
and stops compiling the code.
The package reshape is installed, and I tried to rerun the code without using markdown and it doesn't generate any error.
Is possible that RMarkdown doesn't support melt() function?

Answer 1

Installing a package is not enough — you need to load it. It’s possible that it works in your console because it was still loaded from before, or because you installed it in the current session.
To use the package, you need to add the following into your (R Markdown) code, before using any of its functions:
library(reshape)
Alternatively, you can just prefix all its functions with reshape::. So, instead of calling melt, you’d call reshape::melt. That’s less commonly done but there’s nothing wrong with it.

Answer 2

Load the package inside R markdown. Loading the package outside R markdown is not enough. The loading of package should be inside R chunk in R markdown.
```{r}
library(reshape)
melt(iris)
```

Answer 3

I had the exact same problem and finally solved it. It was caused by setting eval=FALSE inside the code chunk that loaded the libraries in my Markdown document, including reshape2. When I removed that option, it finally worked:
{r setoptions, ***eval=FALSE***}
library(ggplot2)
library(plyr)
library(dplyr)
library(reshape2)
library(knitr)