pylab的目的
Pylab combines the functionality of pyplot with the capabilities of NumPy in a single namespace, and therefore you do not need to import NumPy separately. Furthermore, if you import pylab, pyplot, and NumPy functions can be called directly without any reference to a module (namespace), making the environment more similar to Matlab.
简而言之，from pylab import *这一句话就引入了numpy、matplotlib等常用库，避免了多个import语句。一句话就创造了一个非常类似matlab的编程环境。
pylab的模块包括了许多NumPy和pyplot模块中常用的函数，方便用户快速进行计算和绘图，十分适合在IPython交互式环境中使用。
pylab模块非常单薄，查看pylab源代码可以发现此文件只有80余行，主要内容就是导入一堆包。matplot的主要内容还是在pyplot包中。
阅读以下程序，搜索一下引入的各个包的作用。
from __future__ import (absolute_import, division, print_function, unicode_literals)from matplotlib.externals import siximport sys, warningsfrom matplotlib.cbook import flatten, is_string_like, exception_to_str, \ silent_list, iterable, dedentimport matplotlib as mpl# make mpl.finance module available for backwards compatability, in case folks# using pylab interface depended on not having to import itimport matplotlib.financefrom matplotlib.dates import date2num, num2date,\ datestr2num, strpdate2num, drange,\ epoch2num, num2epoch, mx2num,\ DateFormatter, IndexDateFormatter, DateLocator,\ RRuleLocator, YearLocator, MonthLocator, WeekdayLocator,\ DayLocator, HourLocator, MinuteLocator, SecondLocator,\ rrule, MO, TU, WE, TH, FR, SA, SU, YEARLY, MONTHLY,\ WEEKLY, DAILY, HOURLY, MINUTELY, SECONDLY, relativedeltaimport matplotlib.dates # Do we need this at all?# bring all the symbols in so folks can import them from# pylab in one fell swoop## We are still importing too many things from mlab; more cleanup is needed.from matplotlib.mlab import griddata, stineman_interp, slopes, \ inside_poly, poly_below, poly_between, \ is_closed_polygon, path_length, distances_along_curve, vector_lengthsfrom matplotlib.mlab import window_hanning, window_none, detrend, demean, \ detrend_mean, detrend_none, detrend_linear, entropy, normpdf, \ find, longest_contiguous_ones, longest_ones, \ prctile, prctile_rank, \ center_matrix, rk4, bivariate_normal, get_xyz_where, \ get_sparse_matrix, dist, \ dist_point_to_segment, segments_intersect, fftsurr, movavg, \ exp_safe, \ amap, rms_flat, l1norm, l2norm, norm_flat, frange, identity, \ base_repr, binary_repr, log2, ispower2, \ rec_append_fields, rec_drop_fields, rec_join, csv2rec, rec2csv, isvectorimport matplotlib.mlab as mlabimport matplotlib.cbook as cbookfrom numpy import *from numpy.fft import *from numpy.random import *from numpy.linalg import *from matplotlib.pyplot import *# provide the recommended module abbrevs in the pylab namespaceimport matplotlib.pyplot as pltimport numpy as npimport numpy.ma as ma# don't let numpy's datetime hide stdlibimport datetime# This is needed, or bytes will be numpy.random.bytes from# "from numpy.random import *" abovebytes = __builtins__['bytes']
注释之中列出了可用的命令：
This is a procedural interface to the matplotlib object-oriented
plotting library.The following plotting commands are provided; the majority have
MATLAB |reg| [*]_ analogs and similar arguments... |reg| unicode:: 0xAE
_Plotting commands
acorr - plot the autocorrelation function annotate - annotate something in the figure arrow - add an arrow to the axes axes - Create a new axes axhline - draw a horizontal line across axes axvline - draw a vertical line across axes axhspan - draw a horizontal bar across axes axvspan - draw a vertical bar across axes axis - Set or return the current axis limits autoscale - turn axis autoscaling on or off, and apply it bar - make a bar chart barh - a horizontal bar chart broken_barh - a set of horizontal bars with gaps box - set the axes frame on/off state boxplot - make a box and whisker plot violinplot - make a violin plot cla - clear current axes clabel - label a contour plot clf - clear a figure window clim - adjust the color limits of the current image close - close a figure window colorbar - add a colorbar to the current figure cohere - make a plot of coherence contour - make a contour plot contourf - make a filled contour plot csd - make a plot of cross spectral density delaxes - delete an axes from the current figure draw - Force a redraw of the current figure errorbar - make an errorbar graph figlegend - make legend on the figure rather than the axes figimage - make a figure image figtext - add text in figure coords figure - create or change active figure fill - make filled polygons findobj - recursively find all objects matching some criteria gca - return the current axes gcf - return the current figure gci - get the current image, or None getp - get a graphics property grid - set whether gridding is on hist - make a histogram hold - set the axes hold state ioff - turn interaction mode off ion - turn interaction mode on isinteractive - return True if interaction mode is on imread - load image file into array imsave - save array as an image file imshow - plot image data ishold - return the hold state of the current axes legend - make an axes legend locator_params - adjust parameters used in locating axis ticks loglog - a log log plot matshow - display a matrix in a new figure preserving aspect margins - set margins used in autoscaling pause - pause for a specified interval pcolor - make a pseudocolor plot pcolormesh - make a pseudocolor plot using a quadrilateral mesh pie - make a pie chart plot - make a line plot plot_date - plot dates plotfile - plot column data from an ASCII tab/space/comma delimited file pie - pie charts polar - make a polar plot on a PolarAxes psd - make a plot of power spectral density quiver - make a direction field (arrows) plot rc - control the default params rgrids - customize the radial grids and labels for polar savefig - save the current figure scatter - make a scatter plot setp - set a graphics property semilogx - log x axis semilogy - log y axis show - show the figures specgram - a spectrogram plot spy - plot sparsity pattern using markers or image stem - make a stem plot subplot - make one subplot (numrows, numcols, axesnum) subplots - make a figure with a set of (numrows, numcols) subplots subplots_adjust - change the params controlling the subplot positions of current figure subplot_tool - launch the subplot configuration tool suptitle - add a figure title table - add a table to the plot text - add some text at location x,y to the current axes thetagrids - customize the radial theta grids and labels for polar tick_params - control the appearance of ticks and tick labels ticklabel_format - control the format of tick labels title - add a title to the current axes tricontour - make a contour plot on a triangular grid tricontourf - make a filled contour plot on a triangular grid tripcolor - make a pseudocolor plot on a triangular grid triplot - plot a triangular grid xcorr - plot the autocorrelation function of x and y xlim - set/get the xlimits ylim - set/get the ylimits xticks - set/get the xticks yticks - set/get the yticks xlabel - add an xlabel to the current axes ylabel - add a ylabel to the current axesautumn - set the default colormap to autumn
bone - set the default colormap to bone cool - set the default colormap to cool copper - set the default colormap to copper flag - set the default colormap to flag gray - set the default colormap to gray hot - set the default colormap to hot hsv - set the default colormap to hsv jet - set the default colormap to jet pink - set the default colormap to pink prism - set the default colormap to prism spring - set the default colormap to spring summer - set the default colormap to summer winter - set the default colormap to winter spectral - set the default colormap to spectral_Event handling
connect - register an event handler
disconnect - remove a connected event handler_Matrix commands
cumprod - the cumulative product along a dimension
cumsum - the cumulative sum along a dimension detrend - remove the mean or besdt fit line from an array diag - the k-th diagonal of matrix diff - the n-th differnce of an array eig - the eigenvalues and eigen vectors of v eye - a matrix where the k-th diagonal is ones, else zero find - return the indices where a condition is nonzero fliplr - flip the rows of a matrix up/down flipud - flip the columns of a matrix left/right linspace - a linear spaced vector of N values from min to max inclusive logspace - a log spaced vector of N values from min to max inclusive meshgrid - repeat x and y to make regular matrices ones - an array of ones rand - an array from the uniform distribution [0,1] randn - an array from the normal distribution rot90 - rotate matrix k*90 degress counterclockwise squeeze - squeeze an array removing any dimensions of length 1 tri - a triangular matrix tril - a lower triangular matrix triu - an upper triangular matrix vander - the Vandermonde matrix of vector x svd - singular value decomposition zeros - a matrix of zeros_Probability
normpdf - The Gaussian probability density function
rand - random numbers from the uniform distribution randn - random numbers from the normal distribution_Statistics
amax - the maximum along dimension m
amin - the minimum along dimension m corrcoef - correlation coefficient cov - covariance matrix mean - the mean along dimension m median - the median along dimension m norm - the norm of vector x prod - the product along dimension m ptp - the max-min along dimension m std - the standard deviation along dimension m asum - the sum along dimension m ksdensity - the kernel density estimate_Time series analysis
bartlett - M-point Bartlett window
blackman - M-point Blackman window cohere - the coherence using average periodiogram csd - the cross spectral density using average periodiogram fft - the fast Fourier transform of vector x hamming - M-point Hamming window hanning - M-point Hanning window hist - compute the histogram of x kaiser - M length Kaiser window psd - the power spectral density using average periodiogram sinc - the sinc function of array x_Dates
date2num - convert python datetimes to numeric representation
drange - create an array of numbers for date plots num2date - convert numeric type (float days since 0001) to datetime_Other
angle - the angle of a complex array
griddata - interpolate irregularly distributed data to a regular grid load - Deprecated--please use loadtxt. loadtxt - load ASCII data into array. polyfit - fit x, y to an n-th order polynomial polyval - evaluate an n-th order polynomial roots - the roots of the polynomial coefficients in p save - Deprecated--please use savetxt. savetxt - save an array to an ASCII file. trapz - trapezoidal integration__end
.. [*] MATLAB is a registered trademark of The MathWorks, Inc.