如何使冲积层x轴与y轴上的零点对齐？

Question

我在想我们怎么能把x轴和y轴上的零对齐。我尝试用ylim(0, 1000)来调整限制，但是这似乎不起作用。

library(ggalluvial)
data(vaccinations)

vaccinations <- vaccinations[-c(94),]
levels(vaccinations$response) <- rev(levels(vaccinations$response))
ggplot(vaccinations,
       aes(x = survey, stratum = response, alluvium = subject,
           y = freq,
           fill = response, label = response)) +
  scale_x_discrete(expand = c(.1, .1)) +
  geom_flow() +
  geom_stratum(alpha = .5) +
  geom_text(stat = "stratum", size = 3) +
  theme(legend.position = "none") +
  ggtitle("vaccination survey responses at three points in time")

看这里的情节，用一个蓝色的标记，标记我想要删除的空间。

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Answer 1

ggplot(vaccinations,
           aes(x = survey, stratum = response, alluvium = subject,
               y = freq,
               fill = response, label = response)) +
      scale_x_discrete(expand = c(.1, .1)) +
      #adjust the y scale:
      scale_y_continuous(expand = c(0, 0), limits = c(0, 1000)) +
      geom_flow() +
      geom_stratum(alpha = .5) +
      geom_text(stat = "stratum", size = 3) +
      theme(legend.position = "none") +
      ggtitle("vaccination survey responses at three points in time")

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