如何在r中循环ggplot图形

Question

我有一个数据集（A2），看起来像这样;

Year Gear  Region Landings.t 
1975 Creel  Clyde  3.456 
1976 Creel  Clyde  20.531 
1977 Creel  Clyde  56.241 
1978 Creel  Clyde  43.761 
1975 Creel  Shetland 3.456 
1976 Creel  Shetland 10.531 
1977 Creel  Shetland 46.241 
1978 Creel  Shetland 33.761 

我使用下面的代码来生成一个线图;

ggplot(subset(A2,Region=="Clyde"),aes(x=Year,y=Landings.t,colour=Gear,group=Gear))+ 
    geom_line()+ 
    facet_grid(Gear~.,scales='free_y')+ 
    ggtitle("CLYDE LANDINGS BY GEAR TIME-SERIES")+ 
    theme(panel.background=element_rect(fill='white',colour='black'))+ 
    geom_vline(xintercept=1984) 

此刻我正在复制每个不同区域的代码，这使得我的脚本非常长。我想知道是否有一种方法循环代码来遍历每个区域并为每个区域生成一个图表？

我已经尝试使用前面的问题Loop through a series of qplots可用的答案，但是当我使用此代码时，它返回'二进制运算符的非数字参数'错误。

for(Var in names(A2$Region)){ 
print(ggplot(A2,[,Var],aes(x=Year,y=Landings.t,colour=Gear,group=Gear))+ 
geom_line()+ 
facet_grid(Gear~.,scales='free_y')+ 
ggtitle("CLYDE LANDINGS BY GEAR TIME-SERIES")+ 
theme(panel.background=element_rect(fill='white',colour='black'))+ 
geom_vline(xintercept=1984) 
} 

Answer 1

for(Var in unique(A2$Region)){ 
    print(
    ggplot(
     subset(A2, Region == Var), 
     aes(x = Year, y = Landings.t, colour = Gear, group = Gear) 
    )+ 
    geom_line() + 
    facet_grid(Gear ~ ., scales = 'free_y') + 
    ggtitle("CLYDE LANDINGS BY GEAR TIME-SERIES") + 
    theme(panel.background = element_rect(fill = 'white', colour = 'black'))+ 
    geom_vline(xintercept = 1984) 
) 
} 

或使用plyr包

libary(plyr) 
dlply(A2, ~Region, function(x){ 
    ggplot(
     x, 
     aes(x = Year, y = Landings.t, colour = Gear, group = Gear) 
    )+ 
    geom_line() + 
    facet_grid(Gear ~ ., scales = 'free_y') + 
    ggtitle("CLYDE LANDINGS BY GEAR TIME-SERIES") + 
    theme(panel.background = element_rect(fill = 'white', colour = 'black'))+ 
    geom_vline(xintercept = 1984) 
}) 

plyr可以很容易地拆分沿多个变量的数据集

dlply(A2, ~Region + Species, function(x){ 
    ggplot(
     x, 
     aes(x = Year, y = Landings.t, colour = Gear, group = Gear) 
    )+ 
    geom_line() + 
    facet_grid(Gear ~ ., scales = 'free_y') + 
    ggtitle("CLYDE LANDINGS BY GEAR TIME-SERIES") + 
    theme(panel.background = element_rect(fill = 'white', colour = 'black'))+ 
    geom_vline(xintercept = 1984) 
})