使用ggplot2绘图：错误：提供给连续缩放的离散值

问题描述

 <$>我的数据框的之后将因子更改为 numeric  code $>变量。
 
 $ $ $ $ $ $ $ $ $ $ $ $ $变量$变量= as.numeric（水平（meltDF $变量））[meltDF $变量] 
  

然后执行 ggplot 命令

  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））
  

您将拥有您的图表。

希望这有助于

That's a head of my data frame which I would like to plot.

> 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")

That's the code which I am using for plotting:

## 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))

And as the last the error which I get:

Error: Discrete value supplied to continuous scale

Do you have any idea what's wrong with this code ?It works fine until I try to change the scale so I believe that error is somewhere there...

I tried to figure out if someone has a similar problem because there is already couple of topic like that but it looks like the other problems were mentioned.

That's how to plot look like before adding scale:

解决方案

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

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