如何将Matplotlib中X轴刻度标签移近X轴

我正尝试精简图表，以便将其与其他图表一同放入PPT幻灯片且保持清晰可读。若能将X轴刻度标签移近刻度线会大有帮助，但我不知该如何操作。我已添加了模拟数据，实际文件中这些数据为日期，特此说明。

原代码 #

import matplotlib.pyplot as plt
from matplotlib import rcParams
import matplotlib.dates as dates
import math
from matplotlib.ticker import MaxNLocator
from matplotlib.legend_handler import HandlerLine2D

tva_blue = '#003A70'
lt_grey = '#BFBFBF'
green = '#00B050'
median = '#7F7F7F'
black = '#000000'

x = [10, 20, 30,40, 50, 60, 70, 80]
y = [8, 5, 3, 6, 8, 6, 2, 9]
z = [11, 10, 10, 9, 9, 9, 8, 7]

dates.ConciseDateConverter(x)

labels = x

tfont = {'font': 'arial', 'size': 6.5, 'fontweight': 'bold'}
lfont = {'font': 'arial', 'size': 6, 'fontweight': 'bold'}

#Set Chart Size
rcParams['figure.figsize'] = (2, 1) 
fig, ax = plt.subplots()
fig.set_dpi(400)

# Find Min / Max, use to set y axis dimensions
mx = math.ceil(12)
ymin = round(8)

# Generate Bar Chart with Line interse
plt.bar(x, y, color = tva_blue, width = 20, align = 'center', label = 'Retail Rate (¢/kWh)')
plt.plot(x, z, color = green, lw = 1.5, label = 'Top Quartile')

# Place Date labels onto x axis
plt.xticks(x, labels, fontsize = 5, rotation='vertical')
plt.yticks(y, fontsize = 5)


# Set y axis parameters
plt.ylim(8, (mx))
plt.ylabel("Cents / kWh", fontdict = lfont)
ax.yaxis.set_major_locator(MaxNLocator(integer=True))

#Add title to chart
plt.title('TVA Effective Retail Rate \n 12-Month Rolling Average Trends \nTVA Rate Gap to Top Quartile Utility Co. Peers'
, fontdict=(tfont), fontname = 'Arial', y = 1.32, color = 'black')

# Hide top, right spines
plt.gca().spines['top'].set_visible(False)
plt.gca().spines['right'].set_visible(False)

# Center Ticks, Pad margins
ax.xaxis.set_minor_locator(dates.MonthLocator(bymonthday=16))
ax.tick_params(axis='x', which='minor', tick1On=True, tick2On=False, 
               length = 3)
ax.tick_params(axis='x', which='major', tick1On=False, tick2On=False)
for label in ax.get_xticklabels(minor=True):
    label.set_horizontalalignment('center')
ax.margins(x=0.013)

# Format left and bottom axes
for axis in ['left', 'bottom']:
    ax.spines[axis].set_linewidth(.7)
    ax.spines[axis].set_color(black)

# Format Legend Line Width
def update(handle, orig):
    handle.update_from(orig)
    handle.set_linewidth(2.5)

# Format Legend Location
plt.legend(handler_map={plt.Line2D : HandlerLine2D(update_func=update)}, 
           ncol = 2,  bbox_to_anchor = (0.5, 1.40), loc = 'upper center', 
           frameon = False, fontsize = 5)

# Generate chart    
plt.show()

解决方案 #

要让X轴刻度标签靠近刻度线，核心是通过ax.tick_params()的pad参数控制标签与刻度线的间距，同时针对日期数据优化显示逻辑。以下是修改后的代码及关键说明：

关键调整点 #

• 用ax.tick_params(axis='x', which='major', pad=1)设置主刻度标签的间距，pad值越小，标签离刻度线越近（默认值为4）
• 修正原代码中y轴下限设置错误的问题，避免柱状图被截断
• 替换为真实日期数据模拟，贴合实际使用场景
• 添加plt.tight_layout()优化布局，防止标签被截断

修改后的代码 #

import matplotlib.pyplot as plt
from matplotlib import rcParams
import matplotlib.dates as dates
import math
from matplotlib.ticker import MaxNLocator
from matplotlib.legend_handler import HandlerLine2D
import datetime

tva_blue = '#003A70'
lt_grey = '#BFBFBF'
green = '#00B050'
median = '#7F7F7F'
black = '#000000'

# 模拟实际日期数据
x = [datetime.datetime(2023, i, 1) for i in range(1,9)]
y = [8, 5, 3, 6, 8, 6, 2, 9]
z = [11, 10, 10, 9, 9, 9, 8, 7]

# 格式化日期标签
labels = [d.strftime('%Y-%m') for d in x]

tfont = {'font': 'arial', 'size': 6.5, 'fontweight': 'bold'}
lfont = {'font': 'arial', 'size': 6, 'fontweight': 'bold'}

# 设置图表尺寸
rcParams['figure.figsize'] = (2, 1) 
fig, ax = plt.subplots()
fig.set_dpi(400)

# 计算y轴范围
mx = math.ceil(12)
ymin = 0

# 绘制柱状图和折线图
ax.bar(x, y, color = tva_blue, width = 20, align = 'center', label = 'Retail Rate (¢/kWh)')
ax.plot(x, z, color = green, lw = 1.5, label = 'Top Quartile')

# 设置X轴刻度和标签，调整标签与刻度线的间距
ax.set_xticks(x)
ax.set_xticklabels(labels, fontsize = 5, rotation='vertical')
ax.tick_params(axis='x', which='major', pad=1)  # 关键：缩小标签与刻度线的距离
ax.tick_params(axis='y', fontsize = 5)

# 设置y轴参数
ax.set_ylim(ymin, mx)
ax.set_ylabel("Cents / kWh", fontdict = lfont)
ax.yaxis.set_major_locator(MaxNLocator(integer=True))

# 添加标题
ax.set_title('TVA Effective Retail Rate \n 12-Month Rolling Average Trends \nTVA Rate Gap to Top Quartile Utility Co. Peers'
, fontdict=(tfont), fontname = 'Arial', y = 1.32, color = 'black')

# 隐藏顶部和右侧边框
ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)

# 设置X轴次要刻度
ax.xaxis.set_minor_locator(dates.MonthLocator(bymonthday=16))
ax.tick_params(axis='x', which='minor', tick1On=True, tick2On=False, 
               length = 3, pad=0)
ax.tick_params(axis='x', which='major', tick1On=False, tick2On=False)
for label in ax.get_xticklabels(minor=True):
    label.set_horizontalalignment('center')
ax.margins(x=0.013)

# 格式化左侧和底部边框
for axis in ['left', 'bottom']:
    ax.spines[axis].set_linewidth(.7)
    ax.spines[axis].set_color(black)

# 调整图例线条宽度
def update(handle, orig):
    handle.update_from(orig)
    handle.set_linewidth(2.5)

# 设置图例位置
ax.legend(handler_map={plt.Line2D : HandlerLine2D(update_func=update)}, 
           ncol = 2,  bbox_to_anchor = (0.5, 1.40), loc = 'upper center', 
           frameon = False, fontsize = 5)

# 优化布局并显示图表
plt.tight_layout()
plt.show()

内容的提问来源于stack exchange，提问作者user8346341