对堆叠的geom_bar中的项目进行排序

Question

出于对我来说似乎不错的原因，我希望绘制一个堆积的条形图，条形图以特定的数据相关顺序排列。由于我不明白的原因，它似乎不起作用。具体来说，虽然我可以按照正确的顺序轻松排列我的数据帧的行，并使名称列标识条形成有序因子，因此按照我想要的顺序获取条形图，图形不会列出数据框的列按照我想要的顺序。

一个例子

tab <- structure(list(Item = c("Personal", "Peripheral", "Communication", "Multimedia", "Office", "Social Media"), `Not at all` = c(3.205128, 18.709677, 5.844156, 31.578947, 20.666667, 25.827815), Somewhat = c(30.76923, 23.87097, 24.67532, 18.42105, 30, 16.55629), `Don't know` = c(0.6410256, 2.5806452, 1.9480519, 11.1842105, 2.6666667, 5.9602649), Confident = c(32.69231, 29.67742, 33.11688, 17.10526, 23.33333, 27.15232), `Very confident` = c(32.69231, 25.16129, 34.41558, 21.71053, 23.33333, 24.50331)), .Names = c("Item", "Not at all", "Somewhat", "Don't know", "Confident", "Very confident"), row.names = c(NA, -6L), class = "data.frame")

Title <- 'Plot title'
ResponseLevels <- c("Not at all", "Somewhat", "Don't know", "Confident", "Very confident") # Labels for bars

pal.1 <- brewer.pal(category, 'BrBG') # Colours

tab <- tab %>% arrange(.[,2]) # Sort by first columns of responses
tab$Item <- factor(tab$Item, levels = tab$Item[order(tab[,2])], ordered = TRUE) # Reorder factor levels

tab.m <- melt(tab, id = 'Item')
tab.m$col <- rep(pal.1, each = items) # Set colours

g <- ggplot(data = tab.m, aes(x = Item, y = value, fill = col)) + 
    geom_bar(position = "stack", stat = "identity", aes(group = variable)) +
    coord_flip() +
    scale_fill_identity("Percent", labels = ResponseLevels, 
                        breaks = pal.1, guide = "legend") +
    labs(title = Title, y = "", x = "") +
    theme(plot.title = element_text(size = 14, hjust = 0.5)) +
    theme(axis.text.y = element_text(size = 16,hjust = 0)) +
    theme(legend.position = "bottom")

g

条状的堆叠条从右到左，从“完全没有”到“非常自信”。这些项目的顺序正确，从“多媒体”到“个人”，按照每个项目“完全没有”的比例排序。

我想要得到的是这个图表，其中的响应以另一种方式排序，与图例的方式相同，即从左侧的“根本不是”，到右侧的“非常自信”。我无法弄清楚这个排序是如何设置的，也不知道如何更改它。

我已经阅读了“类似问题”，但看不到这个特定查询的答案。建议，使用ggplot，而不是基础R图形，欢迎使用。

好的，基于allstaire的有用且备受赞赏的答案，我尝试以下

library(tidyverse)

tab <- structure(list(Item = c("Personal", "Peripheral", "Communication", "Multimedia", "Office", "Social Media"), `Not at all` = c(3.205128, 18.709677, 5.844156, 31.578947, 20.666667, 25.827815), Somewhat = c(30.76923, 23.87097, 24.67532, 18.42105, 30, 16.55629), `Don't know` = c(0.6410256, 2.5806452, 1.9480519, 11.1842105, 2.6666667, 5.9602649), Confident = c(32.69231, 29.67742, 33.11688, 17.10526, 23.33333, 27.15232), `Very confident` = c(32.69231, 25.16129, 34.41558, 21.71053, 23.33333, 24.50331)), .Names = c("Item", "Not at all", "Somewhat", "Don't know", "Confident", "Very confident"), row.names = c(NA, -6L), class = "data.frame")

tab <- tab %>% select(1,6,5,4,3,2,1) ## Re-order the columns of tab

tab.m <- tab %>% arrange(`Not at all`) %>%
mutate(Item = factor(Item, levels = Item[order(`Not at all`)])) %>% 
gather(variable, value, -Item, factor_key = TRUE)

ggplot(data = tab.m, aes(x = Item, y = value, fill = variable)) + 
geom_col() +
coord_flip() +
scale_fill_brewer("Percent", type = 'cat', palette = 'BrBG', 
                  guide = guide_legend(reverse = TRUE)) +
labs(title = 'Plot title', y = NULL, x = NULL) +
theme(legend.position = "bottom")

这正是我想要的图表，所以我的紧迫问题就解决了。

但是，如果我改为

ggplot(data = tab.m, aes(x = Item, y = value, fill = variable)) + 
geom_col() +
coord_flip() +
scale_fill_brewer("Percent", type = 'cat', palette = 'BrBG', 
                  guide = guide_legend(reverse = FALSE)) +
labs(title = 'Plot title', y = NULL, x = NULL) +
theme(legend.position = "bottom")

我得到的图片是

这里图表的正文是正确的，但图例的方向是错误的。

这解决了我的问题，但并没有完全回答我的问题。我从数据框开始，为了得到我想要的东西，我必须颠倒数据列的顺序，并反转指南图例。这显然有效，但这是有悖常理的。

那么，堆积条形图如何决定呈现堆叠物品的顺序？它与熔化数据集中的顺序明显相关，但只是更改顺序会使图例朝错误方向移动。查看熔化的数据集tab.m，从上到下，响应的顺序为“非常自信”到“完全没有”，但默认图例的顺序是“完全没有”到“非常自信”

Answer 1

如果您传递的是guide_legend而不是字符串，则可以将其reverse参数设置为TRUE。简化一点，

library(tidyverse)

tab <- structure(list(Item = c("Personal", "Peripheral", "Communication", "Multimedia", "Office", "Social Media"), `Not at all` = c(3.205128, 18.709677, 5.844156, 31.578947, 20.666667, 25.827815), Somewhat = c(30.76923, 23.87097, 24.67532, 18.42105, 30, 16.55629), `Don't know` = c(0.6410256, 2.5806452, 1.9480519, 11.1842105, 2.6666667, 5.9602649), Confident = c(32.69231, 29.67742, 33.11688, 17.10526, 23.33333, 27.15232), `Very confident` = c(32.69231, 25.16129, 34.41558, 21.71053, 23.33333, 24.50331)), .Names = c("Item", "Not at all", "Somewhat", "Don't know", "Confident", "Very confident"), row.names = c(NA, -6L), class = "data.frame")

tab.m <- tab %>% arrange(`Not at all`) %>%
    mutate(Item = factor(Item, levels = Item[order(`Not at all`)])) %>% 
    gather(variable, value, -Item, factor_key = TRUE)

ggplot(data = tab.m, aes(x = Item, y = value, fill = variable)) + 
    geom_col() +
    coord_flip() +
    scale_fill_brewer("Percent", palette = 'BrBG', 
                      guide = guide_legend(reverse = TRUE)) +
    labs(title = 'Plot title', y = NULL, x = NULL) +
    theme(legend.position = "bottom")

编辑：

条形顺序由因子级别顺序决定，在上面由于使用gather来创建因子而由列顺序确定，但coord_flip使其不那么明显。但是，使用levels<-或通过重新组合因子很容易反转级别顺序。要保持颜色具有相同级别，请将direction = -1传递给scale_fill_brewer以反转其顺序。

tab.m <- tab %>% arrange(`Not at all`) %>%
    mutate(Item = factor(Item, levels = Item[order(`Not at all`)])) %>% 
    gather(variable, value, -Item, factor_key = TRUE) %>% 
    mutate(variable = factor(variable, levels = rev(levels(variable)), ordered = TRUE))

ggplot(data = tab.m, aes(x = Item, y = value, fill = variable)) + 
    geom_col() +
    coord_flip() +
    scale_fill_brewer("Percent", palette = 'BrBG', direction = -1,
                      guide = guide_legend(reverse = TRUE)) +
    labs(title = 'Plot title', y = NULL, x = NULL) +
    theme(legend.position = "bottom")