Remove fill around legend key in ggplot

Question

I would like to remove the gray rectangle around the legend. I have tried various methods but none have worked. ``` ggtheme <- theme( axis.text.x = element_text(colour='black'), axis.text.y = element_text(colour='black'), panel.background = element_blank(), panel.grid.minor = element_blank(), panel.grid.major = element_blank(), panel.border = element_rect(colour='black', fill=NA), strip.background = element_blank(), legend.justification = c(0, 1), legend.position = c(0, 1), legend.background = element_rect(colour = NA), legend.key = element_rect(colour = "white", fill = NA), legend.title = element_blank() ) colors <- c("red", "blue") df <- data.frame(year = c(1:10), value = c(10:19), gender = rep(c("male","female"),each=5)) ggplot(df, aes(x = year, y = value)) + geom_point(aes(colour=gender)) + stat_smooth(method = "loess", formula = y ~ x, level=0, size = 1, aes(group = gender, colour=gender)) + ggtheme + scale_color_manual(values = colors) ```

Accepted Answer

You get this grey color inside legend keys because you use `stat_smooth()` that as default makes also confidence interval around the line with some fill (grey if `fill=` isn't used inside the `aes()`).

One solution is to set `se=FALSE` for `stat_smooth()` if you don't need the confidence intervals.

```
  +stat_smooth(method = "loess", formula = y ~ x, level=0, size = 1, 
              aes(group = gender, colour=gender),se=FALSE) 
```

Another solution is to use the function `guides()` and `override.aes=` to remove fill from the legend but keep confidence intervals around lines.

```
  + guides(color=guide_legend(override.aes=list(fill=NA)))
```

Remove fill around legend key in ggplot

Solution

Problem