Python 如何绘制线图？

Python 如何绘制线图？

Creating a timeline with lines, dates, and text：

链接如下：

https://matplotlib.org/stable/gallery/lines_bars_and_markers/timeline.html

# Choose some nice levels
levels = np.tile([-5, 5, -3, 3, -1, 1],
                 int(np.ceil(len(dates)/6)))[:len(dates)]

# Create figure and plot a stem plot with the date
fig, ax = plt.subplots(figsize=(8.8, 4), constrained_layout=True)
ax.set(title="Matplotlib release dates")

ax.vlines(dates, 0, levels, color="tab:red")  # The vertical stems.
ax.plot(dates, np.zeros_like(dates), "-o",
        color="k", markerfacecolor="w")  # Baseline and markers on it.

# annotate lines
for d, l, r in zip(dates, levels, names):
    ax.annotate(r, xy=(d, l),
                xytext=(-3, np.sign(l)*3), textcoords="offset points",
                horizontalalignment="right",
                verticalalignment="bottom" if l > 0 else "top")

# format xaxis with 4 month intervals
ax.xaxis.set_major_locator(mdates.MonthLocator(interval=4))
ax.xaxis.set_major_formatter(mdates.DateFormatter("%b %Y"))
plt.setp(ax.get_xticklabels(), rotation=30, ha="right")

# remove y axis and spines
ax.yaxis.set_visible(False)
ax.spines[["left", "top", "right"]].set_visible(False)

ax.margins(y=0.1)
plt.show()

代码解析，np.ceil 是什么功能？

返回，大于x的最小整数，向上取整；

# 绘制垂直的直线；
ax.vlines(dates, 0, levels, color="tab:red")  # The vertical stems.

# 绘制水平线；
ax.plot(dates, np.zeros_like(dates), "-o",
        color="k", markerfacecolor="w")  # Baseline and markers on it.