python - 用于在 Python 中绘制箱线图的元组、列表和 Numpy 数组

Question

我正在尝试为多个 csv 文件中的列绘制箱线图(当然没有标题行)，但在元组、列表和数组周围遇到了一些困惑。这是我目前所拥有的

    #!/usr/bin/env python

    import csv
    from numpy import *
    import pylab as p
    import matplotlib

    #open one file, until boxplot-ing works
    f = csv.reader (open('2-node.csv'))
    #get all the columns in the file
timeStamp,elapsed,label,responseCode,responseMessage,threadName,dataType,success,bytes,Latency = zip(*f)

    #Make list out of elapsed to pop the 1st element -- the header
    elapsed_list = list(elapsed)
    elapsed_list.pop(0)

    #Turn list back to a tuple
    elapsed = tuple(elapsed_list)

    #Turn list to an numpy array 
    elapsed_array = array(elapsed_list)

    #Elapsed Column statically entered into an array
    data_array = ([4631, 3641, 1902, 1937, 1745, 8937] )

    print data_array #prints in this format: ([xx,xx,xx,xx]), .__class__ is list ... ?
    print elapsed    #prints in this format: ('xx','xx','xx','xx'), .__class__ is tuple
    print elapsed_list # #print in this format: ['xx', 'xx', 'xx', 'xx', 'xx'], .__class__ is list
    print elapsed_array #prints in this format: ['xx' 'xx' 'xx' 'xx' 'xx'] -- notice no commas, .__class__ is numpy.ndarray

    p.boxplot (data_array) #works
    p.boxplot (elapsed) # does not work, error below
    p.boxplit (elapsed_list) #does not work
    p.boxplot (elapsed_array) #does not work
    p.show()

对于箱形图，第一个参数是“an array or a sequence of vectors”，所以我认为 elapsed_array 会起作用……？但是 data_array，一个“列表”，可以工作......但是 elapsed_list` 一个“列表”不......？有没有更好的方法来做到这一点...？

我是 python 的新手，我想了解元组、列表和 numpy 数组之间的差异会阻止此箱线图工作。

示例错误消息是:

Traceback (most recent call last):
  File "../pullcol.py", line 32, in <module>
    p.boxplot (elapsed_list)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/pyplot.py", line 1962, in boxplot
    ret = ax.boxplot(x, notch, sym, vert, whis, positions, widths, patch_artist, bootstrap)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/axes.py", line 5383, in boxplot
    q1, med, q3 = mlab.prctile(d,[25,50,75])
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/mlab.py", line 946, in prctile
    return _interpolate(values[ai],values[bi],frac)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/mlab.py", line 920, in _interpolate
    return a + (b - a)*fraction
TypeError: unsupported operand type(s) for -: 'numpy.ndarray' and 'numpy.ndarray'

Answer 1

elapsed 包含字符串。 Matplotlib 需要整数或 float 来绘制某些东西。尝试将 elapsed 的每个值转换为整数。你可以这样做

elapsed = tuple([int(i) for i in elapsed])

或者正如 FredL 在下面评论的那样:

elapsed_list = array(elapsed_list, dtype=float)