python - 如果另一列中的值未更改，如何在csv的一列中取平均值？

编辑：关于工作代码，请参阅我文章的末尾，从zeekayhere获得。
我有一个CSV文件，有两列（电压和电流）。因为电压被记录到许多有效数字，而电流只有2，所以随着电压值的变化有许多相同的电流值。这对编程并不重要，但我只是解释数据是如何物理获得的。我要执行以下操作：
只要第二列（电流）的值不变，就将第一列（电压）的值收集到一个列表中，并对其进行平均。然后将一行写入一个新的CSV文件，该文件是第一列中电压的平均值和第二列中不变的恒流值。换言之，如果有20行的电流没有变化（比如说它是6 uA），则对20个相应的电压值进行平均（比如这个平均值是600 mV），并在一个新的csv文件中生成一行，该文件读取（'0.6'，'0.000006'）。然后我想继续遍历正在读取的csv，对每组固定电流重复上述过程。
到目前为止，我已经得到了以下代码，但我不确定我是否在正确的轨道上：

import sys, csv
with open('filetowriteto.csv','w') as avg:
    loadeddata = open('filetoreadfrom.csv','r')
    writer=csv.writer(avg)
    readloaded=csv.reader(loadeddata)
    listloaded=list(readloaded)
    oldcurrent=listloaded[0][1]
    for row in readloaded:
        newcurrent = row[1]
        biaslist = []
        if newcurrent == oldcurrent:
            biaslist.append(row[0])
        else :
            biasavg = float(sum(biaslist))/len(biaslist)
            writer.writerow([biasavg,newcurrent])
            newcurrent = row[1]

然后我不知道该去哪里。
编辑：看来泽凯正朝着我想做的方向前进。我正在尝试实现他的itertools.groupby（）方法，但目前正在生成一个空白文件。这是我到目前为止的新代码：

import sys, csv, itertools
with open('VI_avg(12).csv','w') as avg: # this is the file which gets written
    loadeddata = open('VI(12).csv','r') # this is the file which is read
    writer=csv.writer(avg)
    readloaded=csv.reader(loadeddata)
    listloaded=list(readloaded)
    oldcurrent=listloaded[0][1] # looks like this is no longer required
    for current, row in itertools.groupby(readloaded, lambda x: x[1]):
        biaslist = [float(x[0]) for x in row]
        biasavg = float(sum(biaslist))/len(biaslist)
        # write it out
        writer.writerow(biasavg, current)

假设正在打开的CSV文件类似于以下内容（简称示例）：
0.595417，0.000065
0.595177，0.000065
0.594937,0.000065
0.594697,0.000065
0.594457，0.000065
0.594217，0.000065
0.593977，0.000065
0.593737,0.000065
0.593497,0.000064
0.593017，0.000064
0.592777,0.000064
0.592537,0.000064
0.592297,0.000064
0.587018，0.000064
0.586778，0.000064
0.586538,0.000063
0.586299,0.000063
0.586059,0.000063
0.585579，0.000063
0.585339,0.000063
0.585099,0.000063
0.584859,0.000063
0.584619,0.000063
0.584379,0.000063
0.584139，0.000063
0.583899,0.000063
0.583659,0.000063
最终更新：这是工作版本，从zeekay获得：

import csv
import itertools

with open('VI(12).csv') as input, open('VI_avg(12).csv','w') as output:
    reader = csv.reader(input)
    writer = csv.writer(output)
    for current, row in itertools.groupby(reader, lambda x: x[1]):
        biaslist = [float(x[0]) for x in row]
        biasavg = float(sum(biaslist))/len(biaslist)
        writer.writerow([biasavg, current])

最佳答案

当您阅读csv时，可以使用itertools.groupby对结果进行分组，这样可以简化很多事情。根据您更新的示例：

import csv
import itertools

with open('VI(12).csv') as input, open('VI_avg(12).csv','w') as output:
    reader = csv.reader(input)
    writer = csv.writer(output)
    for current, row in itertools.groupby(reader, lambda x: x[1]):
        biaslist = [float(x[0]) for x in row]
        biasavg = float(sum(biaslist))/len(biaslist)
        writer.writerow([biasavg, current])

关于python - 如果另一列中的值未更改，如何在csv的一列中取平均值？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/9399050/