如何在matplotlib中调整自动标记功能,使其正确显示负值？

Question

在过去的几天里,我一直在玩Python,并且发现了很多关于标签的好资源,但是我没有正确显示负值.由于该autolabel()函数采用条形的高度(似乎始终为正值),因此标签在图形中向上显示,当然不会显示为负值.我可以以某种方式获取构成这些条形的值,或者如何将这些标签放在它们所属的位置并将其显示为负值？

import pandas as pd
import matplotlib.pyplot as plt
from builtins import list
import matplotlib
matplotlib.style.use('ggplot')
import numpy as np

n_groups = 2

# create plot
fig, ax = plt.subplots()
fig.canvas.set_window_title('Mindestlohn Bundesweit')
index = np.arange(n_groups)
bar_width = 0.20
opacity = 0.8

list_reallohn_week_vollzeit = [-8.159698443426123, 11.395025597733763]
list_reallohn_week_teilzeit = [-1.048913873322391, 28.99318154295449]
list_reallohn_week_mini = [-7.552596893170488, 7.959096278017519]


rects1 = plt.bar(index + 0.00, list_reallohn_week_vollzeit, bar_width,
             alpha=opacity,
             color='b',
             label='Vollzeit')
rects2 = plt.bar(index + bar_width, list_reallohn_week_teilzeit, bar_width,
             alpha=opacity,
             color='g',
             label='Teilzeit')
rects3 = plt.bar(index + bar_width * 2,list_reallohn_week_mini, bar_width,
             alpha = opacity,
             color='c',
             label='Mini Job')

label_week_lists = ('2014 vor MdL', '2015 Nicht MdL berechtigt', '2015 mit MdL')

plt.ylabel('EUR')
plt.title('Reallöhne pro Woche')
plt.xticks(index + bar_width, label_week_lists)
plt.legend(bbox_to_anchor=(1, 1),
       bbox_transform=plt.gcf().transFigure)

def autolabel(rects, ax):
# Get y-axis height to calculate label position from.
    (y_bottom, y_top) = ax.get_ylim()
    y_height = y_top - y_bottom

    for rect in rects:
        height = rect.get_height()
        # Fraction of axis height taken up by this rectangle
        p_height = (height / y_height)
        # If we can fit the label above the column, do that;
        # otherwise, put it inside the column.
        if p_height > 0.95: # arbitrary; 95% looked good to me.
            label_position = height - (y_height * 0.05)
        else:
            label_position = height + (y_height * 0.01)

        ax.text(rect.get_x() + rect.get_width() / 2., label_position,
            '%d' % int(height),
            ha='center', va='bottom')

autolabel(rects1, ax)
autolabel(rects2, ax)
autolabel(rects3, ax)

plt.show()

Answer 1

mathplotlib 在该部门没有很好的记录。尝试使用该dir()函数来显示您正在处理的容器上的可用选项。我发现有一个.get_y()函数可以在这种情况下返回负数

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试试这个代码

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import pandas as pd\nimport matplotlib.pyplot as plt\nfrom builtins import list\nimport matplotlib\nmatplotlib.style.use('ggplot')\nimport numpy as np\n\nn_groups = 2\n\n# create plot\nfig, ax = plt.subplots()\nfig.canvas.set_window_title('Mindestlohn Bundesweit')\n\nindex = np.arange(n_groups)\nbar_width = 0.20\nopacity = 0.8\n\nlist_reallohn_week_vollzeit = [-8.159698443426123, 11.395025597733763]\nlist_reallohn_week_teilzeit = [-1.048913873322391, 28.99318154295449]\nlist_reallohn_week_mini = [-7.552596893170488, 7.959096278017519]\n\n\nrects1 = plt.bar(index + 0.00, list_reallohn_week_vollzeit, bar_width,\n             alpha=opacity,\n             color='b',\n             label='Vollzeit')\nrects2 = plt.bar(index + bar_width, list_reallohn_week_teilzeit, bar_width,\n             alpha=opacity,\n             color='g',\n             label='Teilzeit')\nrects3 = plt.bar(index + bar_width * 2,list_reallohn_week_mini, bar_width,\n             alpha = opacity,\n             color='c',\n             label='Mini Job')\n\nlabel_week_lists = ('2015 Nicht MdL berechtigt', '2015 mit MdL')\n\nplt.ylabel('EUR')\nplt.title('Reall\xc3\xb6hne pro Woche')\nplt.xticks(index + bar_width, label_week_lists)\nplt.legend(bbox_to_anchor=(1, 1),\n       bbox_transform=plt.gcf().transFigure)\n\ndef autolabel(rects, ax):\n    # Get y-axis height to calculate label position from.\n    (y_bottom, y_top) = ax.get_ylim()\n    y_height = y_top - y_bottom\n\n    for rect in rects:\n    # print(dir(rect))\n\n    height = 0\n    if rect.get_y() < 0:\n        height = rect.get_y()\n    else:\n        height = rect.get_height()\n\n    print(rect.get_height())\n    print( str(rect.get_y()) )\n\n    # Fraction of axis height taken up by this rectangle\n    p_height = (height / y_height)\n    # If we can fit the label above the column, do that;\n    # otherwise, put it inside the column.\n    if p_height > 0.95:  # arbitrary; 95% looked good to me.\n        label_position = height - (y_height * 0.05)\n    else:\n        label_position = height + (y_height * 0.01)\n\n    ax.text(rect.get_x() + rect.get_width() / 2., label_position,\n            '%d' % int(height),\n            ha='center', va='bottom')\n\nautolabel(rects1, ax)\nautolabel(rects2, ax)\nautolabel(rects3, ax)\n\nplt.show()\n

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