Python 使用 matplotlib 将 y 范围更改为从 0 开始

Change y range to start from 0 with matplotlib

提问by Maxime Chéramy

I am using matplotlib to plot data. Here's a code that does something similar:

我正在使用 matplotlib 绘制数据。这是一个执行类似操作的代码：

import matplotlib.pyplot as plt
f, ax = plt.subplots(1)
xdata = [1, 4, 8]
ydata = [10, 20, 30]
ax.plot(xdata, ydata)
plt.show(f)

This shows a line in a graph with the y axis that goes from 10 to 30. While I am satisfied with the x range, I would like to change the y range to start from 0 and adjust on the ymax to show everything.

这在图中显示了一条线，y 轴从 10 到 30。虽然我对 x 范围感到满意，但我想将 y 范围更改为从 0 开始并在 ymax 上进行调整以显示所有内容。

My current solution is to do:

我目前的解决方案是：

ax.set_ylim(0, max(ydata))

However I am wondering if there is a way to just say: autoscale but starts from 0.

但是我想知道是否有一种方法可以说：自动缩放但从 0 开始。

采纳答案by Maxime Chéramy

The range must be set afterthe plot.

范围必须在绘图之后设置。

import matplotlib.pyplot as plt
f, ax = plt.subplots(1)
xdata = [1, 4, 8]
ydata = [10, 20, 30]
ax.plot(xdata, ydata)
ax.set_ylim(ymin=0)
plt.show(f)

If yminis changed before plotting, this will result in a range of [0, 1].

如果ymin在绘图之前更改，这将导致 [0, 1] 的范围。

Edit: the yminargument has been replaced by bottom:

编辑：该ymin参数已被替换为bottom：

ax.set_ylim(bottom=0)

回答by WeizhongTu

Try this

尝试这个

import matplotlib.pyplot as plt
xdata = [1, 4, 8]
ydata = [10, 20, 30]
plt.plot(xdata, ydata)
plt.ylim(ymin=0)  # this line
plt.show()

doc string as following:

文档字符串如下：

>>> help(plt.ylim)
Help on function ylim in module matplotlib.pyplot:

ylim(*args, **kwargs)
    Get or set the *y*-limits of the current axes.

    ::

      ymin, ymax = ylim()   # return the current ylim
      ylim( (ymin, ymax) )  # set the ylim to ymin, ymax
      ylim( ymin, ymax )    # set the ylim to ymin, ymax

    If you do not specify args, you can pass the *ymin* and *ymax* as
    kwargs, e.g.::

      ylim(ymax=3) # adjust the max leaving min unchanged
      ylim(ymin=1) # adjust the min leaving max unchanged

    Setting limits turns autoscaling off for the y-axis.

    The new axis limits are returned as a length 2 tuple.

回答by Sam Sirmaxford

Note that yminwill be removed in Matplotlib 3.2 Matplotlib 3.0.2 documentation. Use bottominstead:

请注意，ymin将在 Matplotlib 3.2 Matplotlib 3.0.2 文档中删除。使用bottom来代替：

import matplotlib.pyplot as plt
f, ax = plt.subplots(1)
xdata = [1, 4, 8]
ydata = [10, 20, 30]
ax.plot(xdata, ydata)
ax.set_ylim(bottom=0)
plt.show(f)