Caner - 2 months ago 8

R Question

I would like to use multiple

`geom_smooth`

We construct a simple dataframe we want to visualize.

`df = data.frame(x = c("a", "b", "c"),`

y1 = seq(1, 3),

y1_upr = seq(2, 4),

y1_lwr = seq(0, 2),

y2 = seq(2, 4),

y2_upr = seq(2.5, 4.5),

y2_lwr = seq(1.5, 3.5))

We can visualize y1 and y2 easily.

`plot_obj = ggplot(data = df, aes(x = x, group = 1)) +`

geom_line(aes(y = y1, colour = "y1")) +

geom_line(aes(y = y2, colour = "y2")) +

scale_colour_manual("", breaks = c("y1", "y2"), values = c("blue", "red"))

plot_obj

If we add one

`geom_smooth`

`plot_obj +`

geom_smooth(aes(y = y1, ymin = y1_lwr, ymax = y1_upr), stat="identity", fill="blue", alpha=0.2)

Lastly, we add the second

`geom_smooth`

`plot_obj +`

geom_smooth(aes(y = y1, ymin = y1_lwr, ymax = y1_upr), stat="identity", fill="blue", alpha=0.2) +

geom_smooth(aes(y = y2, ymin = y2_lwr, ymax = y2_upr), stat="identity", fill="red", alpha=0.2)

Notice that the top line is no longer red in the last chart. Why is this happening and how can it be fixed? Thank you!

Answer

Certainly reshaping your dataset will make things easier, and is the recommended approach. However, if you want to keep using separate layers:

As you haven't mapped a `color`

for `geom_smooth`

, it uses the default color of blue for the smoothed lines it drew. If you want just the ribbon, use `geom_ribbon`

instead.

```
ggplot(data = df, aes(x = x, group = 1)) +
geom_line(aes(y = y1, colour = "y1")) +
geom_line(aes(y = y2, colour = "y2")) +
scale_colour_manual("", breaks = c("y1", "y2"), values = c("blue", "red")) +
geom_ribbon(aes(y = y1, ymin = y1_lwr, ymax = y1_upr), stat="identity", fill="blue", alpha=0.2) +
geom_ribbon(aes(y = y2, ymin = y2_lwr, ymax = y2_upr), stat="identity", fill="red", alpha=0.2)
```

Otherwise you'll need to map your colors for each smooth layer within `aes`

or set them manually to red and blue or NA outside of `aes`

.

```
ggplot(data = df, aes(x = x, group = 1)) +
geom_line(aes(y = y1, colour = "y1")) +
geom_line(aes(y = y2, colour = "y2")) +
scale_colour_manual("", breaks = c("y1", "y2"), values = c("blue", "red")) +
geom_smooth(aes(y = y1, ymin = y1_lwr, ymax = y1_upr, colour = "y1"),
stat="identity", fill="blue", alpha=0.2) +
geom_smooth(aes(y = y2, ymin = y2_lwr, ymax = y2_upr, colour = "y2"),
stat="identity", fill="red", alpha=0.2)
```

Source (Stackoverflow)

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