r - 如何在 ggplot2 的 x 轴中使用月份名称

Question

我尝试使用 ggplot2 在 x 轴上绘制月份，但月份名称会自动显示为带小数的数字。如何强制脚本绘制插入数字的月份名称？我使用了这个代码:

ggplot(df3, aes(x = month, y = PM)) + 
geom_line(aes(col = factor(travel))) + 
xlab("Month") + 
ylab(expression(paste("PM(",mu,"g/", m^3,")", sep=""))) 

数据见下:

df3 <- structure(list(month = c(9, 10, 9, 10, 1, 2, 3, 4, 5, 9, 10, 
                            1, 2, 3, 4, 5, 9, 10, 11, 12, 1, 2, 3, 4, 5, 11), 
                  travel = c("Diesel bus", 
                             "Diesel bus", "Diesel bus", "Diesel bus", "Diesel bus", "Diesel car", 
                             "Diesel car", "Diesel car", "Diesel car", "Diesel car", "Bicycle", 
                             "Bicycle", "Bicycle", "Bicycle", "Bicycle", "Gasoline car", "Gasoline car", 
                             "Gasoline car", "Gasoline car", "Gasoline car", "Elcectric bus", 
                             "Elcectric bus", "Elcectric bus", "Elcectric bus", "Elcectric bus", 
                             "Elcectric bus"), 
                  PM = c(22.6496512922918, 18.1829352554303, 
                         28.776408085308, 30.1441935430254, 23.8938954711914, 21.8288997171693, 
                         22.7177263732526, 29.8606175809457, 30.530998468399, 30.1288699182287, 
                         28.4038889338888, 19.4761033463478, 18.9449487406838, 20.3568456145256, 
                         16.5431814479828, 12.8668955993652, 21.6255497367427, 21.8725590587368, 
                         14.7631275227865, 12.5790810203552, 15.1794028663635, 19.3508881492176, 
                         15.895525373979, 15.3945024820964, 15.5982689292758, 12.1219868087769
                  )),
             .Names = c("month", "travel", "PM"),
             row.names = c(NA, -26L),
             class = "data.frame")

Answer 1

您也可以使用 scale_x_discrete

ggplot(df3, aes(x=month, y=PM)) +
    geom_line(aes(col = factor(travel)))+
    xlab("Month")+ ylab (expression(paste("PM(",mu, "g/", m^3,")", sep=""))) +
    scale_x_discrete(labels=month.abb)