如何移除Matplotlib图表中曲线下方的填充区域

我有一段Matplotlib绘图代码如下：

import pandas as pd
from matplotlib import pyplot as plt

columns = ['Price']
price_values = [[4.2],
    [4.1],
    [4],
    [3.8],
    [3.9],
    [4.2],
    [4.5],
    [4.8],
    [5.2],
    [5.2],
    [5.2],
    [5.6],
    [5.2],
    [5.1],
    [5.3],
    [6],
    [6.2],
    [6.3],
    [6.2],
    [6],
    [5.5] ,
    [5.2],
    [4.8],
    [4.6]]

price_data = pd.DataFrame(price_values, index=range(0, 24), columns=columns)
fig = plt.figure(linewidth=1, figsize=(9, 5))
ax=plt.gca()

for column,color in zip(price_data.columns,['gold']):
    ax.fill_between(
        x=price_data.index,
        y1=price_data[column],
        y2=0,
        label=column,
        color=color,
        alpha=.5,
        step='post',
        linewidth=5,
    )

ax.set_facecolor("white")
ax.set_xlabel("Time of day", fontsize = 14, labelpad=8)
ax.set_ylabel("Price [Cent/kWh]", fontsize = 14,labelpad=8)
ax.set_xlim(0, 23)
ax.set_ylim(0, 8)

plt.xticks(price_data.index, labels=[f'{h:02d}:00' for h in price_data.index], rotation=90)

plt.tight_layout()
hours = list(range(25))
labels = [f'{h:02d}:00' for h in hours]
ax.tick_params(axis='both', which='major', labelsize=14)
ax.legend(loc='center left', bbox_to_anchor=(0.15, 1.07), fontsize = 14, ncol=3)
plt.savefig('Diagramm.png', edgecolor='black', dpi=400, bbox_inches='tight')
plt.show()

我希望移除曲线下方的填充区域，仅保留曲线。尝试使用plt.bar(fill=False)时出现错误：TypeError: bar() missing 2 required positional arguments: 'x' and 'height'，请问有什么解决方法？

解决方法 #

你之前用plt.bar()的思路不对，bar()是绘制柱状图的方法，必须传入x和height两个必填参数，而你需要的是折线图，应该用ax.plot()替代原来的ax.fill_between()，同时保留step='post'参数来保持和原填充边界一致的折线样式。

核心修改部分 #

将原来的fill_between代码块替换为：

for column,color in zip(price_data.columns,['gold']):
    ax.plot(
        price_data.index,
        price_data[column],
        label=column,
        color=color,
        linewidth=5,
        step='post'
    )

完整修改后的代码 #

import pandas as pd
from matplotlib import pyplot as plt

columns = ['Price']
price_values = [[4.2],
    [4.1],
    [4],
    [3.8],
    [3.9],
    [4.2],
    [4.5],
    [4.8],
    [5.2],
    [5.2],
    [5.2],
    [5.6],
    [5.2],
    [5.1],
    [5.3],
    [6],
    [6.2],
    [6.3],
    [6.2],
    [6],
    [5.5] ,
    [5.2],
    [4.8],
    [4.6]]

price_data = pd.DataFrame(price_values, index=range(0, 24), columns=columns)
fig = plt.figure(linewidth=1, figsize=(9, 5))
ax=plt.gca()

# 替换fill_between为plot，仅绘制折线
for column,color in zip(price_data.columns,['gold']):
    ax.plot(
        price_data.index,
        price_data[column],
        label=column,
        color=color,
        linewidth=5,
        step='post'
    )

ax.set_facecolor("white")
ax.set_xlabel("Time of day", fontsize = 14, labelpad=8)
ax.set_ylabel("Price [Cent/kWh]", fontsize = 14,labelpad=8)
ax.set_xlim(0, 23)
ax.set_ylim(0, 8)

plt.xticks(price_data.index, labels=[f'{h:02d}:00' for h in price_data.index], rotation=90)

plt.tight_layout()
hours = list(range(25))
labels = [f'{h:02d}:00' for h in hours]
ax.tick_params(axis='both', which='major', labelsize=14)
ax.legend(loc='center left', bbox_to_anchor=(0.15, 1.07), fontsize = 14, ncol=3)
plt.savefig('Diagramm.png', edgecolor='black', dpi=400, bbox_inches='tight')
plt.show()

关键说明 #

• 移除了fill_between的填充相关参数（如y2=0、alpha=.5），改用plot绘制纯折线
• 保留step='post'确保折线的分段样式和原填充图形的边界完全一致
• 原代码中的linewidth=5参数直接保留，用于控制折线的粗细

内容的提问来源于stack exchange，提问作者PeterBe