Wednesday, November 13, 2013

ggplot2: Cheatsheet for Scatterplots


13 comments:

  1. Thanks! Very clear and helpful.

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  2. Indeed, very clear and helpful. One question: in your last example, you change both colour and shape to vary with vs. Having colour represent vs, and shape, say, am, is not a problem; but how does one construct a suitable legend?

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    Replies
    1. Thanks! You would change scale_shape_manual and scale_color_manual accordingly. I took out the regression lines because it would be confusing but here is the plot with color by vs and shape by am with the legend:

      g2<- ggplot(mtc, aes(x = hp, y = mpg)) +
      geom_point(size=3, aes(color=factor(vs), shape=factor(am))) +
      scale_color_manual(name ="Engine",
      labels=c("V-engine", "Straight"),
      values=c("red","blue")) +
      scale_shape_manual(name ="Transmission",
      labels=c("Automatic", "Manual"),
      values=c(0,2)) +
      theme_bw() +
      theme(
      axis.title.x = element_text(face="bold", color="black", size=12),
      axis.title.y = element_text(face="bold", color="black", size=12),
      plot.title = element_text(face="bold", color = "black", size=12),
      legend.position=c(1,1),
      legend.justification=c(1,1)) +
      labs(x="Horsepower", y = "Miles per Gallon", title= "MPG vs Horsepower by Engine and Transmission")

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    2. Some of the plots are not loading (e.g. 4, 6, 8, 10, ...)

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    3. Hmm, they look fine to me. Which one specifically doesn't load? Or can you send me a screenshot?
      srokicki@fas.harvard.edu

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  3. Hi Rokicki.. I'm also Public Health researcher and admire R very much. Its amazing to learn more of R from your blog. I liked this particular ggplot series on Scatterplot.. I would like to know how we can put the regression equation onto the plot, for example in your plot
    p3 <- p1 + geom_point(color="red") + geom_smooth(method = "lm", se = TRUE) #add regression line

    Thank you.

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    Replies
    1. Hi Manoj, Great question! I have updated the Scatterplot blog post to answer it. Check out the last section now and I hope it helps! Thanks for reading.

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  4. Thanks for sharing, that what useful. However, annotate() is a better way than geom_text(), as you can see from the poor, jagged annotations it produces, caused by printing over and over. See http://stackoverflow.com/questions/11618392/ggplot-text-printed-by-geom-text-is-not-clear

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  5. Thank you very much for taking the initiative to organize this very useful information in a clear and concise way.

    I recently finished MITx's excellent 15.071x MOOC in data analytics, and this post plus your

    http://www.r-bloggers.com/ggplot2-cheatsheet-for-visualizing-distributions/

    complement the visualization unit of that course very well.

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    Replies
    1. Thanks Nick! I'm really glad it's helpful. That class sounds really interesting. I'll check it out.

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