title: R scale_manual use 2 letters as point shape
body: <p>I have a data like here and want to make a scatterplot but instead of points I want to use 2 letter indices of country names (<code>pop_char</code>)  </p>
  
  <pre><code>dat &lt;- structure(list(e1 = c(0.0128, -0.0328, -2e-04, 0.0171, 0.0036, 
  -0.0043, -0.0049, -0.0355, -0.037, -0.003, 0.0061, -3e-04, -0.0401, 
  -0.0214, -0.0343, -0.0408, -0.0108, 0.0158, -0.0161, 0.0247, 
  -0.0068, -0.0208, -0.0199, 0.0084, 0.0032, -0.0126, 0.0068, -0.0048, 
  0.0138, 0.0012, 0.003, -0.0771, -0.0093, 0.008, -0.0367, 0.0145, 
  0.0278, 0.0081, -0.0136, -0.0172, 0.0062, -0.0231, 0.0233, -0.0413, 
  -0.0266, -0.0013, 0.0325, 0.0152, 0.0232, 0.0204), e2 = c(-0.0425, 
  -0.0519, -0.0023, -0.0245, -0.0511, -0.0422, -0.0505, -0.0516, 
  -0.0549, -0.0565, -0.0523, -0.0569, -0.0503, -0.0411, -0.0622, 
  -0.0716, -0.0529, -0.0413, -0.0447, -0.0316, -0.0537, -0.0622, 
  -0.0409, -0.0347, -0.0513, -0.0467, -0.0401, -0.0565, -0.0461, 
  0.0094, -0.0579, -0.0215, -0.0514, -0.0573, -0.0548, -0.0286, 
  -0.0676, 0.0183, -0.0618, -0.0529, -0.0517, -0.0507, -0.0276, 
  -0.0588, -0.063, -0.046, -0.0496, -0.0652, -0.0231, -0.0412), 
      pop_name = structure(c(4L, 11L, 9L, 5L, 2L, 11L, 11L, 11L, 
      7L, 11L, 2L, 2L, 11L, 3L, 11L, 11L, 6L, 6L, 6L, 5L, 7L, 11L, 
      7L, 6L, 11L, 11L, 6L, 11L, 7L, 9L, 2L, 8L, 11L, 2L, 1L, 6L, 
      10L, 9L, 11L, 7L, 7L, 3L, 6L, 11L, 11L, 11L, 5L, 4L, 5L, 
      5L), .Label = c("Albania", "Bosnia", "Bulgaria", "Croatia", 
      "Czech_Republic", "Hungary", "Romania", "Slovakia", "Switzerland", 
      "Ukraine", "Yugoslavia"), class = "factor"), pop_char = structure(c(4L, 
      11L, 9L, 5L, 2L, 11L, 11L, 11L, 7L, 11L, 2L, 2L, 11L, 3L, 
      11L, 11L, 6L, 6L, 6L, 5L, 7L, 11L, 7L, 6L, 11L, 11L, 6L, 
      11L, 7L, 9L, 2L, 8L, 11L, 2L, 1L, 6L, 10L, 9L, 11L, 7L, 7L, 
      3L, 6L, 11L, 11L, 11L, 5L, 4L, 5L, 5L), .Label = c("Al", 
      "Bo", "Bu", "Cr", "Cz", "Hu", "Ro", "Sl", "Sw", "Uk", "Yu"
      ), class = "factor")), .Names = c("e1", "e2", "pop_name", 
  "pop_char"), class = "data.frame", row.names = c("1", "2", "3", 
  "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", 
  "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", 
  "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", 
  "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48", 
  "49", "50"))
  </code></pre>
  
  <p>I came up with:</p>
  
  <pre><code>library(ggplot2)
  ggplot() + 
  geom_point(data=dat, mapping=aes(e1,e2,shape=pop_char,colour=pop_char,size=5)) + 
  scale_shape_manual(values=pop_char)
  </code></pre>
  
  <p>But the plotted letters are not the <code>pop_char</code> column.</p>