在 Python 中，求平均正数和平均负数

Question

当数字为正数时，我想找到平均数，当数字为负数时，我想找到平均数。

import csv


totalCount = 0
numberOfPositives = 0

with open('Weather30States.csv', 'r') as file1:
     val = list(csv.reader(file1))[2]
     val1 = val[0:4]

with open('FL%.csv', 'r') as file2:
    reader = csv.reader(file2)
    reader.next() # this skips the first row of the file
    # this iteration will start from the second row of file2.csv
    conditionMet = False
    for row in reader:
        if conditionMet == True:
            if float(row[0].strip('%')) > 0: # change > to >= if you want to count 0 as positive
                print "FA, 1",row[0],',', ','.join(row[1:5]) # print 1 if positive
                numberOfPositives += 1 # add 1 to numberOfPositives only if positive
            else:
                print "FA, 0",row[0],',', ','.join(row[1:5]) # print 0 if not positive
            totalCount += 1 # add 1 to totalCount regardless of sign
            conditionMet = False # or break if you know you only need at most one line
        if row[1:5] == val1:
           conditionMet = True

print 'Total Count =', totalCount
print 'Percentage of Positive numbers =', numberOfPositives * 100./totalCount, '%'

我是 Python 和 Excel 的新手，不知道在哪里或如何做。

更新

我想要这部分的 row[0] 的平均值：

with open('FL%.csv', 'r') as file2:
    reader = csv.reader(file2)
    reader.next() # this skips the first row of the file
    # this iteration will start from the second row of file2.csv
    conditionMet = False
    for row in reader:
        if conditionMet == True:
            if float(row[0].strip('%')) > 0: # change > to >= if you want to count 0 as positive
                print "FA, 1",row[0],',', ','.join(row[1:5]) # print 1 if positive
                numberOfPositives += 1 # add 1 to numberOfPositives only if positive
            else:
                print "FA, 0",row[0],',', ','.join(row[1:5]) # print 0 if not positive
            totalCount += 1 # add 1 to totalCount regardless of sign
            conditionMet = False # or break if you know you only need at most one line
        if row[1:5] == val1:
           conditionMet = True

Answer 1

您可以随时收集正值和负值，然后在最后取平均值。

from numpy import mean
neg_vals,pos_vals = [],[] #Two empty lists to add values into
#Your code goes here ... ... ... ... 
        if float(row[0].strip('%')) > 0: # change > to >= if you want to count 0 as positive
            print "FA, 1",row[0],',', ','.join(row[1:5]) # print 1 if positive
            numberOfPositives += 1 # add 1 to numberOfPositives only if positive
            pos_vals.append(float(row[0]))
        else:
            print "FA, 0",row[0],',', ','.join(row[1:5]) # print 0 if not positive
            neg_vals.append(float(row[0]))
#Rest of with open as file2
neg_mean = mean(neg_vals)
pos_mean = mean(pos_vals)

您可能必须格式化行[0]（看起来您通常会从中删除“%”）。

此代码的工作原理是在列表出现时将正值和负值添加到列表中。在循环结束时，取两个列表的平均值。根据您希望代码的弹性程度，您可能需要包含一个测试用例，以检测无正值或无负值。