GGPlot2，geom_point颜色取决于情绪错误：提供给连续比例的离散值

Question

我试图根据他们的情绪在世界地图上用颜色绘制推文。我知道它应该很容易做到，但我正努力让它发挥作用。当我尝试查看地图时，它给出了错误：＆＃34;错误：提供给连续刻度的离散值＆＃34;

#if(tweet.sentiment=="positive") {
 # mp = mp + geom_point(aes(x=tweet.x, y=tweet.y), colour = "blue", size=3)
#} else if(tweet.sentiment=="neutral") {
#  mp = mp + geom_point(aes(x=tweet.x, y=tweet.y), colour = "grey90", size=3)
#} else {
#  mp = mp + geom_point(aes(x=tweet.x, y=tweet.y), colour = "darkorange1", size=3)
#}


mp <- mp + geom_point(aes(x=tweetData$tweet.x, y=tweetData$tweet.y, colour=tweetData$tweet.sentiment), size=3) 

mp

Here's a sample of tweetData
         tweet.x    tweet.y  tweet.sentiment
1    -78.9429329  43.897545  negative
2    106.8227450  -6.174465  neutral
3    -84.3879824  33.748995  neutral
4   -118.2436849  34.052234  negative
5    -81.5157535  27.664827  positive
6    -88.7878678  43.784440  positive
7    -74.4056612  40.058324  negative
8    -95.7128910  37.090240  neutral
9    -80.8431267  35.227087  positive