matplotlib & pandas

Python/matplotlab/gallery/ticks_and_spines/centered_ticklabels.md

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+# 居中TickLabels
+
+有时将ticklabels置于中心是件好事。 Matplotlib目前将标签与刻度线关联，标签可以使用水平对齐属性对齐“中心”，“左”或“右”：
+
+```python
+ax.xaxis.set_tick_params(horizontalalignment='right')
+```
+
+但这并没有帮助将标签置于刻度之间。一种解决方案是“伪造它”。 使用次要刻度在主要刻度之间放置一个刻度。这是一个标记月份的示例，以ticks为中心。
+
+![居中TickLabels示例](https://matplotlib.org/_images/sphx_glr_centered_ticklabels_001.png)
+
+```python
+import numpy as np
+import matplotlib.cbook as cbook
+import matplotlib.dates as dates
+import matplotlib.ticker as ticker
+import matplotlib.pyplot as plt
+
+# load some financial data; apple's stock price
+with cbook.get_sample_data('aapl.npz') as fh:
+    r = np.load(fh)['price_data'].view(np.recarray)
+r = r[-250:]  # get the last 250 days
+# Matplotlib works better with datetime.datetime than np.datetime64, but the
+# latter is more portable.
+date = r.date.astype('O')
+
+fig, ax = plt.subplots()
+ax.plot(date, r.adj_close)
+
+ax.xaxis.set_major_locator(dates.MonthLocator())
+ax.xaxis.set_minor_locator(dates.MonthLocator(bymonthday=15))
+
+ax.xaxis.set_major_formatter(ticker.NullFormatter())
+ax.xaxis.set_minor_formatter(dates.DateFormatter('%b'))
+
+for tick in ax.xaxis.get_minor_ticks():
+    tick.tick1line.set_markersize(0)
+    tick.tick2line.set_markersize(0)
+    tick.label1.set_horizontalalignment('center')
+
+imid = len(r) // 2
+ax.set_xlabel(str(date[imid].year))
+plt.show()
+```
+
+## 下载这个示例
+            
+- [下载python源码: centered_ticklabels.py](https://matplotlib.org/_downloads/centered_ticklabels.py)
+- [下载Jupyter notebook: centered_ticklabels.ipynb](https://matplotlib.org/_downloads/centered_ticklabels.ipynb)