如何適應matplotlib中的autolabel函數，使其正確顯示負值？

Question

最近幾天我一直在玩Python，發現很多有關標籤的好東西resources，但是我沒有使它正確顯示負值。由於autolabel()函數獲取了條形的高度，這似乎總是一個正值，所以標籤顯示在圖形中，當然不會顯示爲負值。我能以某種方式獲得組成這些欄的值，或者如何將這些標籤放在他們所屬的位置並將其顯示爲負值？

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沒有在該部門非常有據可查。嘗試使用dir()函數來顯示您正在處理的容器上的可用選項。我發現有一個.get_y()函數retuns在這種情況下負數

試試這個代碼，而不是

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 = ('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: 
    # print(dir(rect)) 

    height = 0 
    if rect.get_y() < 0: 
     height = rect.get_y() 
    else: 
     height = rect.get_height() 

    print(rect.get_height()) 
    print(str(rect.get_y())) 

    # 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 2

如果打印rect.get_height()價值你喜歡的東西：

-8.159698443426123 
11.395025597733763 
-1.048913873322391 
28.99318154295449 
-7.552596893170488 
7.959096278017519 

因此高度酒吧的可能是負的。

爲了紀念負條修改如果自動標籤功能，聲明如下：

if p_height > 0.95: # arbitrary; 95% looked good to me. 
    label_position = height - (y_height * 0.05) if (height > 0) else height + (y_height * 0.05) 
else: 
    label_position = height + (y_height * 0.01) if (height > 0) else height - (y_height * 0.05) 

你必須ajust係數else分支（0.05）手動因爲低於標籤的位置取決於的字體大小標籤。 （由於標籤位於欄的上方，所以正面欄的標籤位置不受字體大小的影響）。

壓軸之作我的字體設置：