making python program from excel files

Question

In a folder "data_last", there are three excel files thay show place, date, temperature, wind speed, humidity. using these data, i want to make each avg, std, max, min prgram by using class. But error....!!

 File "C:/Users/whgoa/PycharmProjects/PythonStudy/assign_last.py", line 76, in <module>
    weath[name] = Grade(open(data_path+name+'.csv','r'))
  File "C:/Users/whgoa/PycharmProjects/PythonStudy/assign_last.py", line 22, in __init__
    self.dt1 = self.dt1.append(self.dt[2])[1:]
TypeError: 'NoneType' object is not subscriptable

and i think there are a lot of errors in my code please tell me what is wrong

import os

data_path = os.getcwd()+'\\data_last\\'
print(data_path)

class Data:
    def __init__(self, file):
        self.file = file.readlines()
        self.dt1, self.dt2, self.dt3 = [], [], []
        for i in range(len(self.file)):
            self.dt = self.file[i].split(',')
            self.dt1 = self.dt1.append(self.dt[2])[1:]
            self.dt1 = [float(i) for i in self.dt1]
            self.dt2 = self.dt2.append(self.dt[3])[1:]
            self.dt2 = [float(i) for i in self.dt2]
            self.dt3 = self.dt3.append(self.dt[4])[1:]
            self.dt3 = [float(i) for i in self.dt3]

class inputError(Exception):
    pass

class Grade(Data):
    def avg(self, subject):
        if subject == 'dt1':
            return sum(self.dt1)/len(self.dt1)
        elif subject == 'dt2':
            return sum(self.dt2)/len(self.dt2)
        elif subject == 'dt3':
            return sum(self.dt3)/len(self.dt3)
        else:
            raise inputError()
    def std(self, subject):
        if subject == 'dt1':
            return (sum([i**2 for i in self.dt1])/len(self.dt1) - self.avg('dt1')**2)**0.5
        elif subject == 'dt2':
            return (sum([i**2 for i in self.dt2])/len(self.dt2) - self.avg('dt2')**2)**0.5
        elif subject == 'dt3':
            return (sum([i**2 for i in self.dt3])/len(self.dt3) - self.avg('dt3')**2)**0.5
        else:
            raise inputError()
    def maximum(self, subject):
        if subject == 'dt1':
            return max(self.dt1)
        elif subject == 'dt2':
            return max(self.dt2)
        elif subject == 'dt3':
            return max(self.dt3)
        else:
            raise inputError
    def minimum(self, subject):
        if subject == 'dt1':
            return min(self.dt1)
        elif subject == 'dt2':
            return min(self.dt2)
        elif subject == 'math':
            return min(self.dt3)
        else:
            raise inputError

weath = dict()

for i in range(2019,2020):
    for j in range(5,6):
        for k in range(24,27):
            name = str(i)+'_'+str(j)+'_'+str(k)
            weath[name] = Grade(open(data_path+name+'.csv','r'))

for i in range(2019,2020):
    for j in range(5,6):
        for k in range(24,27):
            name = str(i)+'_'+str(j)+'_'+str(k)
            print('{0}year {1}month {2}day temp avg: {3}, std : {4}, max : {5}, min : {6}\n'.format(i, j, k, weath[name].avg('dt1'), weath[name].std('dt1'), weath[name].maximum('dt1'), weath[name].minimum('dt1')))
            print('{0}year {1}month {2}day temp avg: {3}, std : {4}, max : {5}, min : {6}\n'.format(i, j, k, weath[name].avg('dt2'), weath[name].std('dt2'), weath[name].maximum('dt2'), weath[name].minimum('dt2')))
            print('{0}year {1}month {2}day temp avg: {3}, std : {4}, max : {5}, min : {6}\n'.format(i, j, k, weath[name].avg('dt3'), weath[name].std('dt3'), weath[name].maximum('dt3'), weath[name].minimum('dt3')))
        print('\n')
    print('\n')

``append`` mutate the list and returns ``None``. Assigning the result of ``append`` or slicing it with ``[1:]`` does not make sense. — MisterMiyagi, Jun 07 '19 at 11:42

score -1 · Answer 1 · answered Jun 07 '19 at 12:03

The error is because you are trying to use subscripting on a method:

self.dt1 = self.dt1.append(self.dt[2])[1:]

.append()

is a method for lists and you can't use slicing with methods unless they are returning something.

I still don't understand why you need to use slicing after appending but if you provide the details maybe I could give a workaround.

P.S. : Unless this is the only way it needs to be done, I would recommend using Pandas library for the task, you can efficiently extract the data from an excel file as well as find the statistical measures with few lines of code.

place date temp wind humid 112 2019-05-24 1:00 17.5 1.1 65 112 2019-05-24 2:00 17.5 2.2 66 the form of excel is like this. so, i want remove the first line. That's why i did slicing! — haejin, Jun 07 '19 at 12:30

making python program from excel files

1 Answers1