LONGITUDE LATITUDE NUM_PICKUPS TOTAL_REVENUE
 1   121.6177  38.9124          21         337.0
 2   121.8069  39.0210          16         454.7
 3   121.5723  38.9645          38         696.9
 4   121.6423  38.9258         622       13609.7
 5   121.5647  38.9129         116        2016.7
 6   121.6429  38.8846         120        2417.3
 7   121.5852  38.9279         117        1975.0
 8   121.6616  38.9189          94        1712.4
 9   121.5812  38.9828          50         981.6
 10  121.6411  38.9255         225        4696.2

看到这一点,第一列和第二列是经度和纬度.

mydata [1,3] = 21意味着在地方(121.6177,38.9124),有21个拾取.

然后,我使用NUM_PICKUPS desc来获取mydata：

LONGITUDE   LATITUDE    NUM_PICKUPS TOTAL_REVENUE
121.6019    39.0181        14243    514716
121.5382    38.9609        13244    443754.7
121.5381    38.9609         9645    325056
121.5382    38.9608         8846    294345.6
121.602     39.0181         6556    232254.5
121.5383    38.9609         6152    208967.6
121.5383    38.9608         6014    207677.8
121.5381    38.9608         5544    185398.3
121.6018    39.018          4546    167662.1
121.5382    38.9607         4260    143088.9
121.5827    38.8948         4133    72202.8
121.6303    38.9183         3837    67683.6
121.5966    38.9665         3747    56378.7

还有mydata的摘要：

summary(mydata)
 
 
 LONGITUDE        LATITUDE      NUM_PICKUPS       TOTAL_REVENUE     
  Min.   :121.1   Min.   :38.76   Min.   :   10.00   Min.   :    92.9  
  1st Qu.:121.6   1st Qu.:38.91   1st Qu.:   15.00   1st Qu.:   289.7  
  Median :121.6   Median :38.92   Median :   27.00   Median :   515.1  
  Mean   :121.6   Mean   :38.93   Mean   :   57.03   Mean   :  1067.6  
  3rd Qu.:121.6   3rd Qu.:38.96   3rd Qu.:   59.00   3rd Qu.:  1089.5  
  Max.   :122.0   Max.   :39.32   Max.   :14243.00   Max.   :514716.0

现在,我想绘制由NUM_PICKUPS着色的地图,查看我的代码.

g1 <- ggplot() + geom_point(data = mydata,aes(x = LONGITUDE,y = LATITUDE,color=NUM_PICKUPS))

是的,代码和图表都是正确的,但看起来颜色,很难识别出具有高num_pickups的地方在哪里？哪里少？

我尝试使用scale_colour_gradient()修改我的代码：

g1 + scale_colour_gradient(low = "red",high = "white")

但看图片,颜色也难以分类.

第三次尝试：这次我添加了alpha = I(1/100)和break()的参数：

g1 <- ggplot() + geom_point(data = mydata,color=NUM_PICKUPS),alpha=I(1/100))
g1 + scale_colour_gradient(low = "red",high = "white",breaks=c(0,2000,4000))

但它仍然无助！

第四次尝试：

ggplot(data = mydata,color = NUM_PICKUPS)) + geom_point() + scale_colour_gradient(limits = c(0,60))

第五次尝试：
根据3年前的帖子,ggplot2 Color Scale Over Affected by Outliers,我尝试再次修改我的代码：

mydata$NUM_PICKUPS1 <- "> 2000"
mydata$NUM_PICKUPS1[mydata$NUM_PICKUPS <= 2000] <- NA
 
g2 <- ggplot() + geom_point(data = subset(mydata,NUM_PICKUPS <= 2000),size=2) +    geom_point(data = subset(mydata,NUM_PICKUPS > 2000),fill=NUM_PICKUPS1))

异常值确实发生了变化,但色标仍难以分类！

那么,我的问题是如何修改我的代码以便轻松识别NUM_PICKUPS的颜色？