Animate it!

We can animate these plots after modification using gifski and tweenr.

df7 <- df3 %>% filter(!is.na(price), !is.na(recind)) %>%
  mutate(ind=ifelse(recind=="No Recession in 12 months",1,0))


myxy2<- function(rr=1, in.df=df7,vv="T10Y2YM"){
  x<-filter(in.df, ind==ifelse(rr==1,-1,0),symbol=vv)$price
  outdf<- data.frame(
    x=density(x)$x[which.max(density(x)$y)],  #find maximum density (in y dimension)
    y=max(density(x)$y,na.rm=T)
  )
}


myxy <- function(rr=1,in.df=df7,vv="T10Y2YM", N= 600){
  if (rr== -1) {rr=c(0,1)}
  x<-filter(in.df, ind %in% rr,symbol==vv)$price
  outdf<- data.frame(
    x=density(x,n=N)$x,  #find maximum density (in y dimension)
    y=density(x,n=N)$y,
    ind=case_when(rr==1~-1,
                  rr==0~1),
    rind=case_when(rr==1~"Recession in 12 months",
                   rr==0 ~"No Recession in 12 months",
                   T ~ "All months"))
  }

df8a <-   bind_rows(myxy(1),myxy(0)) %>% mutate(rind="All",ind=0)
df8b <-   myxy(-1,N=1200) %>% mutate(rind="All",ind=0)
df8 <- 
  bind_rows(df8b) %>%
  keep_state(30) %>%
  tween_state(  bind_rows(myxy(1),myxy(0)),'linear',20) %>%
  keep_state(50)

myplot2<- function(i=1){
  ggplot(data=filter(df8,.frame==i), aes(x=x,y=y,fill=ind,group=paste0(rind,":",ind)))+
    geom_area(alpha=0.55,color=NA)+
    scale_fill_gradient2(name="Recession 12 months from now?   ",limits=c(-1,1),
                         breaks=c(-1,0,1),labels=c("No Recession", "All points", "Recession"),
                         low="#4575b4",mid="gray",high="#d73027")+
    scale_color_gradient2(name="Recession 12 months from now?   ",limits=c(-1,1),
                          breaks=c(-1,0,1),labels=c("No Recession", "All points", "Recession"),
                          low="#4575b4",mid="gray",high="#d73027")+
    scale_x_continuous(breaks=seq(-5,5,1),limits=c(-5.5,5.5))+
    scale_y_continuous(limits=c(0,0.76))+
    theme_minimal_vgrid()+
    labs(x="Spread in percentage points",y="Empirical Density Function",
         title="U.S. Treasury Yield Curve: 10-year minus 2-year Constant Maturity Yield",
         caption="@lenkiefer Source: U.S. Treasury, monthly averages, NBER recessions")+
    theme(legend.position="top",
          legend.key.width=unit(2,"cm"),
          plot.caption=element_text(hjust=0),
          plot.title=element_text(face="bold"),
          strip.text=element_text(face="bold"))+
    geom_vline(data=filter(df3,date==max(date),symbol=="T10Y2YM"), inherit.aes=FALSE,aes(xintercept=vlast), linetype=2)+
    geom_text(data=df3 %>% filter(date==max(date), symbol=="T10Y2YM"),color="black",hjust=1,inherit.aes=FALSE,
              aes(x=vlast,y=0.2,label=paste0("August 7, 2019: ", vlast," ")))
}

N2<- max(df8$.frame)

t1 <-Sys.time()
gif_file <- save_gif({for (i in seq((1):N2)){  
  g<- myplot2(i)+ guides(fill = guide_legend(reverse=T))
  print(g)
  print(paste(i,"out of",N2))
}
  for (ii in 1:1){
    print(g)
    print(paste(ii,"out of",30))
  }
  # Set mydir to some place to store your ouptut file
}, gif_file= paste0(mydir,"/yc10y2y.gif"),width = 900, height = 600, res = 92, delay=1/20)
t2 <- Sys.time()
t2-t1

df9a <-   bind_rows(myxy(1,vv="T10Y3MM"),myxy(0,vv="T10Y3MM")) %>% mutate(rind="All",ind=0)
df9b <-   myxy(-1,N=1200,vv="T10Y3MM") %>% mutate(rind="All",ind=0)
df9 <- 
  bind_rows(df9b) %>%
  keep_state(30) %>%
  tween_state(  bind_rows(myxy(1,vv="T10Y3MM"),myxy(0,vv="T10Y3MM")),'linear',20) %>%
  keep_state(50)


myplot3<- function(i=1){
  ggplot(data=filter(df9,.frame==i), aes(x=x,y=y,fill=ind,group=paste0(rind,":",ind)))+
    geom_area(alpha=0.55,color=NA)+

    scale_fill_gradient2(name="Recession 12 months from now?   ",limits=c(-1,1),
                         breaks=c(-1,0,1),labels=c("No Recession", "All points", "Recession"),
                         low="#4575b4",mid="gray",high="#d73027")+
    scale_color_gradient2(name="Recession 12 months from now?   ",limits=c(-1,1),
                          breaks=c(-1,0,1),labels=c("No Recession", "All points", "Recession"),
                          low="#4575b4",mid="gray",high="#d73027")+
    scale_x_continuous(breaks=seq(-5,5,1),limits=c(-5.5,5.5))+
    scale_y_continuous(limits=c(0,0.6))+
    theme_minimal_vgrid()+
    labs(x="Spread in percentage points",y="Empirical Density Function",
         title="U.S. Treasury Yield Curve: 10-year minus 3-month Constant Maturity Yield",
         caption="@lenkiefer Source: U.S. Treasury, monthly averages, NBER recessions")+
    theme(legend.position="top",
          legend.key.width=unit(2,"cm"),
          plot.caption=element_text(hjust=0),
          plot.title=element_text(face="bold"),
          strip.text=element_text(face="bold"))+
    geom_vline(data=filter(df3,date==max(date),symbol=="T10Y3MM"), inherit.aes=FALSE,aes(xintercept=vlast), linetype=2)+
    geom_text(data=df3 %>% filter(date==max(date), symbol=="T10Y3MM"),color="black",hjust=1,inherit.aes=FALSE,
              aes(x=vlast,y=0.2,label=paste0("August 7, 2019: ", vlast," ")))
}

N3<- max(df9$.frame)

t1 <-Sys.time()
gif_file <- save_gif({for (i in seq((1):N3)){  
  g<- myplot3(i)+ guides(fill = guide_legend(reverse=T))
  print(g)
  print(paste(i,"out of",N3))
}
  for (ii in 1:1){
    print(g)
    print(paste(ii,"out of",30))
  }
}, gif_file= paste0(mydir,"/yc10y3m.gif"),width = 900, height = 600, res = 92, delay=1/20)
t2 <- Sys.time()
t2-t1