Numpy 和 Matplotlib 基础

运行环境：win32，python3.6，IDLE

Numpy 和 Matplotlib安装

Numpy ：pip install numpy

matplotlib： 下载预Matplotlib编译的安装包，注意选择Python的版本和系统的位数 使用pip包管理器安装，在命令行中输入：pip install 下载安装包的完整路径 打开Python

如果import maplotlib和import numpy可以正常载入，则表明安装成功。

使用help命令查看两个函数库的描述如下：

DESCRIPTION
NumPy
=====
Provides
1. An array object of arbitrary homogeneous items
2. Fast mathematical operations over arrays
3. Linear Algebra, Fourier Transforms, Random Number Generation

---

NAME
matplotlib.pyplot - Provides a MATLAB-like plotting framework.

DESCRIPTION
:mod:~matplotlib.pylab combines pyplot with numpy into a single namespace.
This is convenient for interactive work, but for programming it
is recommended that the namespaces be kept separate, e.g.:

    import numpy as np    import matplotlib.pyplot as plt    #    x = np.arange(0, 5, 0.1);    y = np.sin(x)    plt.plot(x, y)

help()查看常用函数

np.arange()

help(np.arange)arange(...)    arange([start,] stop[, step,], dtype=None)    Return evenly spaced values within a given interval.    Values are generated within the half-open interval ``[start, stop)``    (in other words, the interval including `start` but excluding `stop`).    For integer arguments the function is equivalent to the Python built-in    `range <http://docs.python.org/lib/built-in-funcs.html>`_ function,    but returns an ndarray rather than a list.    When using a non-integer step, such as 0.1, the results will often not    be consistent.  It is better to use ``linspace`` for these cases.    Parameters    ----------    start : number, optional        Start of interval.  The interval includes this value.  The default        start value is 0.    stop : number        End of interval.  The interval does not include this value, except        in some cases where `step` is not an integer and floating point        round-off affects the length of `out`.    step : number, optional        Spacing between values.  For any output `out`, this is the distance        between two adjacent values, ``out[i+1] - out[i]``.  The default        step size is 1.  If `step` is specified, `start` must also be given.    dtype : dtype        The type of the output array.  If `dtype` is not given, infer the data        type from the other input arguments.    Returns    -------    arange : ndarray        Array of evenly spaced values.        For floating point arguments, the length of the result is        ``ceil((stop - start)/step)``.  Because of floating point overflow,        this rule may result in the last element of `out` being greater        than `stop`.    See Also    --------    linspace : Evenly spaced numbers with careful handling of endpoints.    ogrid: Arrays of evenly spaced numbers in N-dimensions.    mgrid: Grid-shaped arrays of evenly spaced numbers in N-dimensions.    Examples    --------    >>> np.arange(3)    array([0, 1, 2])    >>> np.arange(3.0)    array([ 0.,  1.,  2.])    >>> np.arange(3,7)    array([3, 4, 5, 6])    >>> np.arange(3,7,2)    array([3, 5])