ggplot如何控制图表的宽度？

最下面一个图没有图例结果宽度就和上面三张图不一样了。。。有什么办法可以让四个图的宽度一致吗？前三个图的图例还是需要的。
代码如下：

1. p1<-ggplot(saturday,aes(x=hours))+geom_point(aes(y=Ridership,size=1,alpha=0.6,color="Ridership"))+
   
2.   geom_point(aes(y=moving_average,size=1,alpha=0.6,color="moving_average"))+
   
3.   labs(title="Saturday Hourly Ridership")+
   
4.   theme(plot.title = element_text(hjust = 0.5,size=28))+
   
5.   theme(text = element_text(size=25))+
   
6.   guides(alpha=FALSE)+guides(size=FALSE)+
   
7.   ylab("Daily Ridership")+
   
8.   scale_colour_discrete(breaks = c('Ridership','moving_average'), labels = c('Daily Ridership','Moving Average'))+
   
9.   xlim(0,168)
   
10. 
    
11. p2<-ggplot(sunday,aes(x=hours))+geom_point(aes(y=Ridership,size=1,alpha=0.6,color="Ridership"))+
    
12.   geom_point(aes(y=moving_average,size=1,alpha=0.6,color="moving_average"))+
    
13.   labs(title="Sunday Hourly Ridership")+
    
14.   theme(plot.title = element_text(hjust = 0.5,size=28))+
    
15.   theme(text = element_text(size=25))+
    
16.   guides(alpha=FALSE)+guides(size=FALSE)+
    
17.   ylab("Daily Ridership")+
    
18.   scale_colour_discrete(breaks = c('Ridership','moving_average'), labels = c('Daily Ridership','Moving Average'))+
    
19.   xlim(0,168)
    
20. 
    
21. p3<-ggplot(weekday,aes(x=hours))+geom_point(aes(y=Ridership,size=1,alpha=0.6,color="Ridership"))+
    
22.   geom_point(aes(y=moving_average,size=1,alpha=0.6,color="moving_average"))+
    
23.   labs(title="WeekDay Hourly Ridership")+
    
24.   theme(plot.title = element_text(hjust = 0.5,size=28))+
    
25.   theme(text = element_text(size=25))+
    
26.   guides(alpha=FALSE)+guides(size=FALSE)+
    
27.   ylab("Daily Ridership")+
    
28.   scale_colour_discrete(breaks = c('Ridership','moving_average'), labels = c('Daily Ridership','Moving Average'))+
    
29.   xlim(0,168)
    
30. 
    
31. p4<-ggplot(mydataframe,aes(x=hours,y=residual))+geom_line()+
    
32.   labs(title="WeekDay Hourly Ridership")+
    
33.   theme(plot.title = element_text(hjust = 0.5,size=28))+
    
34.   theme(text = element_text(size=25))+
    
35.   guides(alpha=FALSE)+guides(size=FALSE)+
    
36.   ylab("Daily Ridership")+
    
37. geom_hline(yintercept = 0)
    
38.   xlim(0,168)
    
39. easyGgplot2::ggplot2.multiplot(p1,p2,p3,p4,cols = 1)

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用gridExtra工具包可以实现，比如你可以画两个图，用代码grid.arrange(g1,g2,ncol=2,widths=c(1,2),heights=1)其中g1 和g2是两个ggplot的图，具体详情请看分析资料： https://bbs.pinggu.org/forum.php?mod=viewthread&tid=5866021&extra=， 或者查阅gridExtra工具包帮助文件

1. library(cowplot)
   
2. ggdraw() +
   
3.   draw_plot(p4, x = 0, y = 0,   width = .9, height = .25) +
   
4.   draw_plot(p1, x = 0, y = .25, width = 1,  height = .25) +
   
5.   draw_plot(p2, x = 0, y = .5,  width = 1,  height = .25) +
   
6.   draw_plot(p3, x = 0, y = .75, width = 1,  height = .25)

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