쌓인 geom_bar 내 항목 순서

나에게 좋은 이유 때문에 특정 데이터 종속 순서로 막대가있는 누적 막대 차트를 그리려고합니다. 나에게 모호한 이유로 작동하지 않는 것 같습니다. 특히, 데이터 프레임의 행을 올바른 순서로 쉽게 정렬하고 막대를 식별하는 이름 열을 정렬 된 요소로 만들 수 있으므로 원하는 순서대로 막대를 가져 오면 그래프에 데이터 프레임의 열이 나열되지 않습니다. 내가 원하는 순서대로.

예

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

The stacked pieces of the bars run from right to left, from 'Not at all' to 'Very confident'. The items are in the correct order, from 'Multimedia' to 'Personal', ordered by the proportion of those who said 'Not at all' to each item.

What I want to get is this graph with the responses ordered the other way, the same way as the legend, that is from 'Not at all' on the left, to 'Very confident' on the right. I cannot figure out how this ordering is set, nor how to change it.

I've read through the 'similar questions', but can see no answer to this specific query. Suggestions, using ggplot, not base R graphics, welcome.

Ok, building on the useful, and much appreciated answer from allstaire, I try the following

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")

And this is exactly the graph I want, so my pressing problem is solved.

However, if I say instead

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")

The picture I get is this

Here the body of the chart is correct, but the legend is going in the wrong direction.

This solves my problem, but does not quite answer my question. I start with a dataframe, and to get what I want I have to reverse the order of the data columns, and reverse the guide legend. This evidently works, but it's perverse.

So, how does a stacked bar chart decide in what order to present the stacked items? It's clearly related to their order in the melted dataset, but simply changing the order leaves the legend going in the wrong direction. Looking at the melted dataset, tab.m, from top to bottom, the responses are in the order 'Very confident' to 'Not at all', but the default legend is the reverse order 'Not at all' to 'Very confident'.