The plotting code below gives `Error: Discrete value supplied to continuous scale`

What’s wrong with this code? It works fine until I try to change the scale so the error is there… I tried to figure out solutions from similar problem but couldn’t.

This is a `head`

of my data:

```
> dput(head(df))
structure(list(`10` = c(0, 0, 0, 0, 0, 0), `33.95` = c(0, 0,
0, 0, 0, 0), `58.66` = c(0, 0, 0, 0, 0, 0), `84.42` = c(0, 0,
0, 0, 0, 0), `110.21` = c(0, 0, 0, 0, 0, 0), `134.16` = c(0,
0, 0, 0, 0, 0), `164.69` = c(0, 0, 0, 0, 0, 0), `199.1` = c(0,
0, 0, 0, 0, 0), `234.35` = c(0, 0, 0, 0, 0, 0), `257.19` = c(0,
0, 0, 0, 0, 0), `361.84` = c(0, 0, 0, 0, 0, 0), `432.74` = c(0,
0, 0, 0, 0, 0), `506.34` = c(1, 0, 0, 0, 0, 0), `581.46` = c(0,
0, 0, 0, 0, 0), `651.71` = c(0, 0, 0, 0, 0, 0), `732.59` = c(0,
0, 0, 0, 0, 1), `817.56` = c(0, 0, 0, 1, 0, 0), `896.24` = c(0,
0, 0, 0, 0, 0), `971.77` = c(0, 1, 1, 1, 0, 1), `1038.91` = c(0,
0, 0, 0, 0, 0), MW = c(3.9, 6.4, 7.4, 8.1, 9, 9.4)), .Names = c("10",
"33.95", "58.66", "84.42", "110.21", "134.16", "164.69", "199.1",
"234.35", "257.19", "361.84", "432.74", "506.34", "581.46", "651.71",
"732.59", "817.56", "896.24", "971.77", "1038.91", "MW"), row.names = c("Merc",
"Peug", "Fera", "Fiat", "Opel", "Volv"
), class = "data.frame")
```

The plotting code:

```
## Plotting
meltDF = melt(df, id.vars = 'MW')
ggplot(meltDF[meltDF$value == 1,]) + geom_point(aes(x = MW, y = variable)) +
scale_x_continuous(limits=c(0, 1200), breaks=c(0, 400, 800, 1200)) +
scale_y_continuous(limits=c(0, 1200), breaks=c(0, 400, 800, 1200))
```

Here’s how the plot looked before adding scale:

### 3 Answers

As mentioned in the comments, there **cannot be a continuous scale on variable of the factor type**. You could change the

`factor`

to `numeric`

as follows, just after you define the `meltDF`

variable.```
meltDF$variable=as.numeric(levels(meltDF$variable))[meltDF$variable]
```

Then, execute the `ggplot`

command

```
ggplot(meltDF[meltDF$value == 1,]) + geom_point(aes(x = MW, y = variable)) +
scale_x_continuous(limits=c(0, 1200), breaks=c(0, 400, 800, 1200)) +
scale_y_continuous(limits=c(0, 1200), breaks=c(0, 400, 800, 1200))
```

And you will have your chart.

Hope this helps

if `x`

is numeric, then add `scale_x_continuous()`

; if `x`

is character/factor, then add `scale_x_discrete()`

. This might solve your problem.

In my case, you need to convert the column(you think this column is numeric, but actually not) to `numeric`

```
geom_segment(data=tmpp,
aes(x=start_pos,
y=lib.complexity,
xend=end_pos,
yend=lib.complexity)
)
# to
geom_segment(data=tmpp,
aes(x=as.numeric(start_pos),
y=as.numeric(lib.complexity),
xend=as.numeric(end_pos),
yend=as.numeric(lib.complexity))
)
```