使用 matplotlib 降低 x 軸值

Question

如何繪制條形圖，其中 x 軸值按從高到低的降序排列？

例子：

出於示例目的，我的繪圖如下所示：

我需要圖表對其繪制星期一（最大值）、星期三、星期二（最小值）（分別）的位置進行排序

這是我到目前為止所擁有的：

x_axis = ['a','b','c'...'z']
y_axis = [#...#...#] number values for each letter in xaxis

def barplot(x_axis, y_axis): #x and y axis defined in another function
    x_label_pos = range(len(y_axis))
    plot.bar(x_label_pos, y_axis)
    plot.yticks(range(0, int(max(y_axis) + 2), 2))
    plot.xticks(x_axis) 

Answer 1

# grab a reference to the current axes
ax = plt.gca()
# set the xlimits to be the reverse of the current xlimits
ax.set_xlim(ax.get_xlim()[::-1])
# call `draw` to re-render the graph
plt.draw()

如果將 x 限制設置為左值大於右值（與 y 軸相同）， matplotlib將“做正確的事”。

Answer 2

所以下面是一個最小的例子，可以滿足你的需要。 您的問題實際上與 matplotlib 無關，而只是根據需要重新排序輸入數據的一種情況。

import matplotlib.pyplot as plt

# some dummy lists with unordered values 
x_axis = ['a','b','c']
y_axis = [1,3,2]

def barplot(x_axis, y_axis): 
    # zip the two lists and co-sort by biggest bin value         
    ax_sort = sorted(zip(y_axis,x_axis), reverse=True)
    y_axis = [i[0] for i in ax_sort]
    x_axis = [i[1] for i in ax_sort]

    # the above is ugly and would be better served using a numpy recarray

    # get the positions of the x coordinates of the bars
    x_label_pos = range(len(x_axis))

    # plot the bars and align on center of x coordinate
    plt.bar(x_label_pos, y_axis,align="center")

    # update the ticks to the desired labels
    plt.xticks(x_label_pos,x_axis)


barplot(x_axis, y_axis)
plt.show()