matplotlib 使用
matplotlib 的使用
1. pyplot和pylab的区别
pyplot模块提供了一套和MATLAB类似的绘图API。pylab模块，包括了许多NumPy和pyplot模块中常用的函数，方便用户快速进行计算和绘图。可以从pylab的源码中看出来：
2. pyplot模块里的函数
2.1 函数汇总
（详见 https://matplotlib.org/api/pyplot_summary.html）
函数 | 说明 |
acorr(x[, hold, data]) | Plot the autocorrelation of x. |
angle_spectrum(x[, Fs, Fc, window, pad_to, …]) |
Plot the angle spectrum. 画角谱图（信号处理，光学） |
annotate(*args, **kwargs) |
Annotate the point xy with text s. 给图片添加注释（可指定被注释的位置，用于注释的字符串位置） |
arrow(x, y, dx, dy[, hold]) |
Add an arrow to the axes. 给坐标轴添加箭头 |
autoscale([enable, axis, tight]) | Autoscale the axis view to the data (toggle). |
autumn() |
Set the colormap to “autumn”. 将colormap设置成autumn |
axes([arg]) | Add an axes to the current figure and make it the current axes. |
axhline([y, xmin, xmax, hold]) |
Add a horizontal line across the axis. 沿着坐标轴添加一条水平线 |
axhspan(ymin, ymax[, xmin, xmax, hold]) |
Add a horizontal span (rectangle) across the axis. 沿着坐标轴添加一条水平矩形 |
axis(*v, **kwargs) | Convenience method to get or set axis properties. |
axvline([x, ymin, ymax, hold]) |
Add a vertical line across the axes. 沿着坐标轴添加一条竖直线条 |
axvspan(xmin, xmax[, ymin, ymax, hold]) |
Add a vertical span (rectangle) across the axes. 沿着坐标轴添加一条竖直矩形 |
bar(*args, **kwargs) |
Make a bar plot. 绘制bar |
barbs(*args, **kw) | Plot a 2-D field of barbs. |
barh(*args, **kwargs) |
Make a horizontal bar plot. 绘制水平bar |
bone() |
Set the colormap to “bone”. 将colormap设置成bone |
box([on]) | Turn the axes box on or off. |
boxplot(x[, notch, sym, vert, whis, …]) | Make a box and whisker plot. |
broken_barh(xranges, yrange[, hold, data]) | Plot a horizontal sequence of rectangles. |
cla() |
Clear the current axes. 清除当前坐标 |
clabel(CS, *args, **kwargs) | Label a contour plot. |
clf() |
Clear the current figure. 清除当前图像（用一个figure连续绘制不同图时可能会用到） |
clim([vmin, vmax]) | Set the color limits of the current image. |
close(*args) | Close a figure window. |
cohere(x, y[, NFFT, Fs, Fc, detrend, …]) | Plot the coherence between x and y. |
colorbar([mappable, cax, ax]) |
Add a colorbar to a plot. 添加colorbar |
colors() | . |
connect(s, func) | Connect event with string s to func. |
contour(*args, **kwargs) |
Plot contours. 绘制contour图（与MATLAB中的类似） |
contourf(*args, **kwargs) | Plot contours. |
cool() | Set the colormap to “cool”. |
copper() | Set the colormap to “copper”. |
csd(x, y[, NFFT, Fs, Fc, detrend, window, …]) | Plot the cross-spectral density. |
delaxes([ax]) | Remove the given Axes ax from the current figure. |
disconnect(cid) | Disconnect callback id cid |
draw() | Redraw the current figure. |
errorbar(x, y[, yerr, xerr, fmt, ecolor, …]) | Plot y versus x as lines and/or markers with attached errorbars. |
eventplot(positions[, orientation, …]) | Plot identical parallel lines at the given positions. |
figimage(*args, **kwargs) | Adds a non-resampled image to the figure. |
figlegend(*args, **kwargs) | Place a legend in the figure. |
fignum_exists(num) | |
figtext(*args, **kwargs) | Add text to figure. |
figure([num, figsize, dpi, facecolor, …]) | Creates a new figure. |
fill(*args, **kwargs) | Plot filled polygons. |
fill_between(x, y1[, y2, where, …]) | Fill the area between two horizontal curves. |
fill_betweenx(y, x1[, x2, where, step, …]) | Fill the area between two vertical curves. |
findobj([o, match, include_self]) | Find artist objects. |
flag() | Set the colormap to “flag”. |
gca(**kwargs) | Get the current Axes instance on the current figure matching the given keyword args, or create one. |
gcf() | Get a reference to the current figure. |
gci() | Get the current colorable artist. |
Return a list of existing figure labels. | |
Return a list of existing figure numbers. | |
Get a sorted list of all of the plotting commands. | |
ginput(*args, **kwargs) | Blocking call to interact with a figure. |
gray() |
Set the colormap to “gray”. 将colorbar设置成gray |
grid([b, which, axis]) | Turn the axes grids on or off. |
hexbin(x, y[, C, gridsize, bins, xscale, …]) | Make a hexagonal binning plot. |
hist(x[, bins, range, density, weights, …]) | Plot a histogram. |
hist2d(x, y[, bins, range, normed, weights, …]) | Make a 2D histogram plot. |
hlines(y, xmin, xmax[, colors, linestyles, …]) | Plot horizontal lines at each y from xmin to xmax. |
hold([b]) | . |
hot() | Set the colormap to “hot”. |
hsv() | Set the colormap to “hsv”. |
imread(*args, **kwargs) | Read an image from a file into an array. |
imsave(*args, **kwargs) | Save an array as in image file. |
imshow(X[, cmap, norm, aspect, …]) | Display an image on the axes. |
inferno() | Set the colormap to “inferno”. |
Install a repl display hook so that any stale figure are automatically redrawn when control is returned to the repl. | |
ioff() |
Turn interactive mode off. 交互模式关 |
ion() |
Turn interactive mode on. 设置交互模式开 |
ishold() | . |
Return status of interactive mode. | |
jet() | Set the colormap to “jet”. |
legend(*args, **kwargs) |
Places a legend on the axes. 添加legend |
locator_params([axis, tight]) | Control behavior of tick locators. |
loglog(*args, **kwargs) | Make a plot with log scaling on both the x and y axis. |
magma() | Set the colormap to “magma”. |
magnitude_spectrum(x[, Fs, Fc, window, …]) | Plot the magnitude spectrum. |
margins(*args, **kw) | Set or retrieve autoscaling margins. |
matshow(A[, fignum]) | Display an array as a matrix in a new figure window. |
Remove minor ticks from the current plot. | |
Display minor ticks on the current plot. | |
Set the colormap to “nipy_spectral”. | |
over(func, *args, **kwargs) | . |
pause(interval) |
Pause for interval seconds. figure显示interval 秒再进行下面的操作 |
pcolor(*args, **kwargs) | Create a pseudocolor plot of a 2-D array. |
pcolormesh(*args, **kwargs) | Plot a quadrilateral mesh. |
phase_spectrum(x[, Fs, Fc, window, pad_to, …]) | Plot the phase spectrum. |
pie(x[, explode, labels, colors, autopct, …]) | Plot a pie chart. |
pink() | Set the colormap to “pink”. |
plasma() | Set the colormap to “plasma”. |
plot(*args, **kwargs) | Plot y versus x as lines and/or markers. |
plot_date(x, y[, fmt, tz, xdate, ydate, …]) | Plot data that contains dates. |
plotfile(fname[, cols, plotfuncs, comments, …]) | Plot the data in a file. |
polar(*args, **kwargs) | Make a polar plot. |
prism() | Set the colormap to “prism”. |
psd(x[, NFFT, Fs, Fc, detrend, window, …]) | Plot the power spectral density. |
quiver(*args, **kw) | Plot a 2-D field of arrows. |
quiverkey(*args, **kw) | Add a key to a quiver plot. |
rc(*args, **kwargs) |
Set the current rc params. 设置rc参数 |
rc_context([rc, fname]) | Return a context manager for managing rc settings. |
Restore the rc params from Matplotlib’s internal defaults. | |
rgrids(*args, **kwargs) | Get or set the radial gridlines on a polar plot. |
savefig(*args, **kwargs) | Save the current figure. |
sca(ax) | Set the current Axes instance to ax. |
scatter(x, y[, s, c, marker, cmap, norm, …]) | A scatter plot of y vs x with varying marker size and/or color. |
sci(im) | Set the current image. |
semilogx(*args, **kwargs) | Make a plot with log scaling on the x axis. |
semilogy(*args, **kwargs) | Make a plot with log scaling on the y axis. |
set_cmap(cmap) | Set the default colormap. |
setp(*args, **kwargs) | Set a property on an artist object. |
show(*args, **kw) | Display a figure. |
specgram(x[, NFFT, Fs, Fc, detrend, window, …]) | Plot a spectrogram. |
spectral() | Set the colormap to “spectral”. |
spring() | Set the colormap to “spring”. |
spy(Z[, precision, marker, markersize, aspect]) | Plot the sparsity pattern on a 2-D array. |
stackplot(x, *args, **kwargs) | Draws a stacked area plot. |
stem(*args, **kwargs) | Create a stem plot. |
step(x, y, *args, **kwargs) | Make a step plot. |
streamplot(x, y, u, v[, density, linewidth, …]) | Draws streamlines of a vector flow. |
subplot(*args, **kwargs) | Return a subplot axes at the given grid position. |
subplot2grid(shape, loc[, rowspan, colspan, fig]) | Create an axis at specific location inside a regular grid. |
subplot_tool([targetfig]) | Launch a subplot tool window for a figure. |
subplots([nrows, ncols, sharex, sharey, …]) | Create a figure and a set of subplots |
subplots_adjust(*args, **kwargs) | Tune the subplot layout. |
summer() | Set the colormap to “summer”. |
suptitle(*args, **kwargs) | Add a centered title to the figure. |
switch_backend(newbackend) | Switch the default backend. |
table(**kwargs) | Add a table to the current axes. |
text(x, y, s[, fontdict, withdash]) | Add text to the axes. |
thetagrids(*args, **kwargs) | Get or set the theta locations of the gridlines in a polar plot. |
tick_params([axis]) | Change the appearance of ticks, tick labels, and gridlines. |
ticklabel_format(**kwargs) | Change the ScalarFormatter used by default for linear axes. |
tight_layout([pad, h_pad, w_pad, rect]) | Automatically adjust subplot parameters to give specified padding. |
title(s, *args, **kwargs) | Set a title of the current axes. |
tricontour(*args, **kwargs) | Draw contours on an unstructured triangular grid. |
tricontourf(*args, **kwargs) | Draw contours on an unstructured triangular grid. |
tripcolor(*args, **kwargs) | Create a pseudocolor plot of an unstructured triangular grid. |
triplot(*args, **kwargs) | Draw a unstructured triangular grid as lines and/or markers. |
twinx([ax]) | Make a second axes that shares the x-axis. |
twiny([ax]) | Make a second axes that shares the y-axis. |
Uninstalls the matplotlib display hook. | |
violinplot(dataset[, positions, vert, …]) | Make a violin plot. |
viridis() | Set the colormap to “viridis”. |
vlines(x, ymin, ymax[, colors, linestyles, …]) | Plot vertical lines. |
waitforbuttonpress(*args, **kwargs) | Blocking call to interact with the figure. |
winter() | Set the colormap to “winter”. |
xcorr(x, y[, normed, detrend, usevlines, …]) | Plot the cross correlation between x and y. |
xkcd([scale, length, randomness]) | Turns on xkcd sketch-style drawing mode. |
xlabel(s, *args, **kwargs) | Set the x axis label of the current axis. |
xlim(*args, **kwargs) | Get or set the x limits of the current axes. |
xscale(*args, **kwargs) | Set the scaling of the x-axis. |
xticks(*args, **kwargs) | Get or set the x-limits of the current tick locations and labels. |
ylabel(s, *args, **kwargs) | Set the y axis label of the current axis. |
ylim(*args, **kwargs) | Get or set the y-limits of the current axes. |
yscale(*args, **kwargs) | Set the scaling of the y-axis. |
yticks(*args, **kwargs) | Get or set the y-limits of the current tick locations and labels. |
2.2 确定坐标范围
plt.axis([xmin, xmax, ymin, ymax])
2.3 文本函数
- plt.xticks()/plt.yticks() 设置坐标轴的刻度显示的值。
- plt.legend() 添加图例
- text() - add text at an arbitrary location to the Axes; matplotlib.axes.Axes.text() in the API.
- xlabel() - add a label to the x-axis; matplotlib.axes.Axes.set_xlabel() in the API.
- ylabel() - add a label to the y-axis; matplotlib.axes.Axes.set_ylabel() in the API.
- title() - add a title to the Axes; matplotlib.axes.Axes.set_title() in the API.
- figtext() - add text at an arbitrary location to the Figure; matplotlib.figure.Figure.text() in the API.
- suptitle() - add a title to the Figure; matplotlib.figure.Figure.suptitle() in the API.
- annotate() - add an annotation, with optional arrow, to the Axes ; matplotlib.axes.Axes.annotate() in the API.参数xy表示的标注位置和xytext表示的文本位置。 这两个参数都是(x, y)元组。
举例如下：
# -*- coding: utf-8 -*-
import matplotlib.pyplot as plt
fig = plt.figure()
fig.suptitle('bold figure suptitle', fontsize=14, fontweight='bold')
ax = fig.add_subplot(111)
fig.subplots_adjust(top=0.85)
ax.set_title('axes title')
ax.set_xlabel('xlabel')
ax.set_ylabel('ylabel')
ax.text(3, 8, 'boxed italics text in data coords', style='italic',
bbox={'facecolor':'red', 'alpha':0.5, 'pad':10})
ax.text(2, 6, r'an equation: $E=mc^2$', fontsize=15)
ax.text(3, 2, u'unicode: Institut f\374r Festk\366rperphysik')
ax.text(0.95, 0.01, 'colored text in axes coords',
verticalalignment='bottom', horizontalalignment='right',
transform=ax.transAxes,
color='green', fontsize=15)
ax.plot([2], [1], 'o')
ax.annotate('annotate', xy=(2, 1), xytext=(3, 4),
arrowprops=dict(facecolor='black', shrink=0.05))
ax.axis([0, 10, 0, 10])
plt.show()
2.4 保存图片savefig
利用plt.savefig可以将当前图表保存到文件。例如：
Plt.savefig(‘figpath.svg’,dpi = 400, bbox_inches = ‘tight’ )选项：
Fname： 含有路径的字符串或python文件型对象。.pdf,.png根据扩展名推断得出。
dpi: 图像分辨率（每英寸点数），默认为100
facecolor，edgecolor： 图像的背景色，默认为‘w’（白色）
format： 显式设置文件格式（‘png’，‘pdf’，‘svg’，‘ps’，‘eps’…）
bbox_inches：图表需要保存的部分。如果设置为‘tight’，则尝试剪除图表周围的空白部分。
2.5 采用对数坐标
plt.xscale('log')
plt.yscale('linear')
plt.yscale('log')
plt.yscale('logit')
plt.yscale('symlog', linthreshy=0.05)3. 属性
3.1 可用属性汇总
下面是可用的Line2D属性（https://www.jianshu.com/p/c495e663f0ed）：
属性 | 值类型 |
alpha | 浮点值 |
animated | [True / False] |
antialiased or aa | [True / False] |
clip_box | matplotlib.transform.Bbox实例 |
clip_on | [True / False] |
clip_path | Path实例，Transform，以及Patch实例 |
color or c | 任何matplotlib颜色 |
contains | 命中测试函数 |
dash_capstyle | ['butt' / 'round' / 'projecting'] |
dash_joinstyle | ['miter' / 'round' / 'bevel'] |
dashes | 以点为单位的连接/断开墨水序列 |
data | (np.array xdata, np.array ydata) |
figure | matplotlib.figure.Figure实例 |
label | 任何字符串 |
linestyle or ls | [ '-' / '--' / '-.' / ':' / 'steps' / ...] |
linewidth or lw | 以点为单位的浮点值 |
lod | [True / False] |
marker | [ '+' / ',' / '.' / '1' / '2' / '3' / '4' ] |
markeredgecolor or mec | 任何matplotlib颜色 |
markeredgewidth or mew | 以点为单位的浮点值 |
markerfacecolor or mfc | 任何matplotlib颜色 |
markersize or ms | 浮点值 |
markevery | [ None / 整数值 / (startind, stride) ] |
picker | 用于交互式线条选择 |
pickradius | 线条的拾取选择半径 |
solid_capstyle | ['butt' / 'round' / 'projecting'] |
solid_joinstyle | ['miter' / 'round' / 'bevel'] |
transform | matplotlib.transforms.Transform实例 |
visible | [True / False] |
xdata | np.array |
ydata | np.array |
zorder | 任何数值 |
更多内容参考官方文档: https://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.plot
3.2 线条风格
线条风格linestyle或ls | 描述 | 线条风格linestyle或ls | 描述 |
‘-‘ | 实线 | ‘:’ | 虚线 |
‘–‘ | 破折线 | ‘None’,’ ‘,” | 什么都不画 |
‘-.’ | 点划线 |
| |
3.3 线条标记
标记maker | 描述 | 标记 | 描述 |
‘o’ | 圆圈 | ‘.’ | 点 |
‘D’ | 菱形 | ‘s’ | 正方形 |
‘h’ | 六边形1 | ‘*’ | 星号 |
‘H’ | 六边形2 | ‘d’ | 小菱形 |
‘_’ | 水平线 | ‘v’ | 一角朝下的三角形 |
‘8’ | 八边形 | ‘ | 一角朝左的三角形 |
‘p’ | 五边形 | ‘>’ | 一角朝右的三角形 |
‘,’ | 像素 | ‘^’ | 一角朝上的三角形 |
‘+’ | 加号 | ‘ | 竖线 |
‘None’,”,’ ‘ | 无 | ‘x’ | X |
3.4 颜色设置
可以通过调用matplotlib.pyplot.colors()得到matplotlib支持的所有颜色。
别名 | 颜色 | 别名 | 颜色 |
b | 蓝色 | g | 绿色 |
r | 红色 | y | 黄色 |
c | 青色 | k | 黑色 |
m | 洋红色 | w | 白色 |
如果颜色不够用，还可以通过如下3种其他方式来定义颜色值：
- 使用HTML十六进制字符串
color='eeefff' - 使用合法的HTML颜色名字（’red’,’chartreuse’等）。
- 也可以传入一个归一化到[0,1]的RGB元祖。
color=(0.3,0.3,0.4)
很多方法可以添加颜色参数，例如：
plt.tilte('Title in a custom color',color='#123456'）
3.2 背景色
通过设定axisbg参数，可以设定背景色，如：
subplot(111, axisbg=(0.1843,0.3098,0.3098))
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