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70

answers:

2

I am trying to make a faceted plot in ggplot2 of the coefficients on the regressors from two linear models with the same predictors. The data frame I constructed is this:

r.together>
          reg         coef        se      y
1  (Intercept)  5.068608671 0.6990873 Labels
2     goodTRUE  0.310575129 0.5228815 Labels
3    indiaTRUE -1.196868662 0.5192330 Labels
4    moneyTRUE -0.586451273 0.6011257 Labels
5     maleTRUE -0.157618168 0.5332040 Labels
6  (Intercept)  4.225580743 0.6010509  Bonus
7     goodTRUE  1.272760149 0.4524954  Bonus
8    indiaTRUE -0.829588862 0.4492838  Bonus
9    moneyTRUE -0.003571476 0.5175601  Bonus
10    maleTRUE  0.977011737 0.4602726  Bonus

The "y" column is a label for the model, reg are the regressors and coef and se are what you would think.

I want to plot:

g <- qplot(reg, coef, facets=.~y, data = r.together) + coord_flip() 

But when I try to display the plot, I get:

> print(g)
Error in names(df) <- output : 
'names' attribute [2] must be the same length as the vector [1]

What's strange is that

qplot(reg, coef, colour=y, data = r.together) + coord_flip()

plots as you would expect.

+4  A: 

I don't know why, but the name y seems to be the problem. If you change it, then it works

r.together <- read.table(textConnection("
          reg         coef        se      myfactor
 (Intercept)  5.068608671 0.6990873 Labels
    goodTRUE  0.310575129 0.5228815 Labels
   indiaTRUE -1.196868662 0.5192330 Labels
   moneyTRUE -0.586451273 0.6011257 Labels
    maleTRUE -0.157618168 0.5332040 Labels
 (Intercept)  4.225580743 0.6010509  Bonus
    goodTRUE  1.272760149 0.4524954  Bonus
   indiaTRUE -0.829588862 0.4492838  Bonus
   moneyTRUE -0.003571476 0.5175601  Bonus
    maleTRUE  0.977011737 0.4602726  Bonus
"),header=T)

qplot(reg, coef, data = r.together, facets= .~myfactor ) + coord_flip() 
gd047
Yep - that was it! Thanks!
John Horton
It seems John was faster than me..
momobo
Yes, this is a long standing bug, which I hope I'll be able to fix this summer.
hadley
+2  A: 

Could be y a reserved word?

r.together=data.frame(
  reg=c("(Intercept)", "goodTRUE", "indiaTRUE", "moneyTRUE", "maleTRUE", "(Intercept)", "goodTRUE", "indiaTRUE", "moneyTRUE", "maleTRUE"),
  coef=c(5.068608671, 0.310575129, -1.196868662, -0.586451273, -0.157618168, 4.225580743, 1.272760149, -0.829588862, -0.003571476, 0.977011737),
  se=c(0.6990873, 0.5228815, 0.519233, 0.6011257, 0.533204, 0.6010509, 0.4524954, 0.4492838, 0.5175601, 0.4602726),
  yy= c("Labels", "Labels", "Labels", "Labels", "Labels", "Bonus", "Bonus", "Bonus", "Bonus", "Bonus")
 )

yy seems to work

g <- qplot(reg, coef, data = r.together,facets=. ~ yy) +coord_flip()
momobo