1. Detailed usage of numpy.linspace
numpy.linspace(start, stop, num=50, endpoint=True, retstep=False, dtype=None)
Returns evenly spaced numbers within the specified interval.
Return num uniformly distributed samples in [start, stop].
The endpoints of this interval can be excluded arbitrarily.
Examples
>>>
>>> np.linspace(2.0, 3.0, num=5)
array([ 2. , 2.25, 2.5 , 2.75, 3. ])
>>> np.linspace(2.0, 3.0, num=5, endpoint=False)
array([ 2. , 2.2, 2.4, 2.6, 2.8])
>>> np.linspace(2.0, 3.0, num=5, retstep=True)
(array([ 2. , 2.25, 2.5 , 2.75, 3. ]), 0.25)
2. The use of asterisk (*) in python, that is, (*train_x.shape)
3. Numpy learning-np.random.randn(), np.random.rand() and np.random.randint()
4. Matplotlib-data visualization plt.plot
How to use plt.legend in matplotlib
plt.plot(x,y,ls,lw,c,marker,markersize,markeredgecolor,markerfacecolor,label)
Set the standard and form of line drawing.
Parameter description:
**x: ** abscissa; **y: ** vertical coordinate;
**ls or linestyle: ** the form of the line ('-','–',':' and'-.');
**lw (or linewidth): ** the width of the line;
**c:** the color of the line;
**marker:** the shape of the point on the line;
**markersize or ms: **marker size, floating point type;
**markerfacecolor: **point fill color;
**markeredgecolor: the edge color of the marker
label: **Text label
#Note: The ro below is the format_string parameter in the plot function, r-red, o-filled circle mark
plt.plot(train_X,train_Y,'ro',label ='Original data')#Display simulated data points
5. Python multiple graphs are displayed in different windows at the same time
如下代码所示,首先要为每个图建立一个figure,这样每个图会单独显示在一个窗口中;然后等所有图代码都写好后在最后面加上plt.show(),这样每张图就可以在不同窗口中同时显示了。
————————————————
# 绘制图1
plt.figure()
plt.plot(y, 'b-', linewidth=2)
plt.legend()
plt.grid(True)
# 绘制图2
plt.figure()
plt.plot(z, 'b-', linewidth=2)
plt.legend()
plt.grid(True)
————————————————
原文链接:https://blog.csdn.net/sinat_35821976/article/details/84950697
6, python can't write a line
a = 'te' \
'st'
a=('te'
'st')
7. The difference between from...import * statement and import
- import module : Import a module; Note: It is equivalent to import a folder, which is a relative path.
- from...import : Import a function in a module; Note: It is equivalent to import a file in a folder, which is an absolute path.
The difference between from...import * statement and import is:
Import imports a module, and every time you use a function in the module, you must determine which module it is.
from...import * Import a module. Every time you use a function in the module, you can use the function directly; note that you already know that the function belongs to that module.