如何在Python 3中从文件创建频率表作为列表？

Question

I am trying to take results from a survey (in a txt file). This file includes results about major, age, sex, whether they work, whether they have children, and whether they own a PC (those last three are represented as 0 and 1 in the data file for no and yes). I want to calculate and create relative frequency lists based on their age group and draw a bar chart for them. I need to read the file into memory and break up the lines into fields. I need to create three lists based on Work, Have Children, and Own PC. The age group is a string, I need a count "column" that counts the number of yes answers, I need a column representing the total responses for each age group, and I need a percent column for each age group which is the count/total*100. The ideal output should look like this:

[["<=20",6,7,85.71429],["21-23",5,6,83.33333],...,[">=30",5,12,41.66667]]

I have written code for this but it's not returning anything at all, and I'm not sure if the way that I went about this was correct (I am a beginner and am trying to learn by myself).

def process_file(filename,index):
    infile=open(filename, "r")
    frequencyTable = [["<=20", 0,0,0,],["21-23",0,0,0],["24-26",0,0,0],["27-29",0,0,0],[">=30",0,0,0]]

    firstLine = True
    for line in filename:
        if firstLine == True:
            firstLine = False
        continue
        columns = line.split(',')
        columns[-1] = columns[-1].split("\n")[0]
        if int(columns[1] <= 20):
            Table[0][1] +=int(columns(ColumnNum))
            Table[0][2] += 1
            Table[0][3] = (Table[0][1]/Table[0][2]) *100
        elif int(columns[1]) >=21 and int(columns[1]) <=23:
            Table[1][1] +=int(columns[index])
            Table[1][2] += 1
            Table[1][3] = (Table[1][1]/Table[1][2]) *100
        elif int(columns[1]) >=24 and int(columns[1]) <=26:
            Table[2][1] +=int(columns[index])
            Table[2][2] += 1
            Table[2][3] = (Table[2][1]/Table[2][2]) *100
        elif int(columns[1]) >=27 and int(columns[1]) <=29:
            Table[3][1] +=int(columns[index])
            Table[3][2] += 1
            Table[3][3] = (Table[3][1]/Table[3][2]) *100
        elif int(columns[1]) >=30:
            Table[4][1] +=int(columns[index])
            Table[4][2] += 1
            Table[4][3] = (Table[4][1]/Table[4][2]) *100
            firstline = False
    return Table
    infile.close()

If anyone has any input on this, any and all help is appreciated!

Answer 1

I won't rewrite your entire code, but you might want to try using a dictionary

results={'major': [],'age': [],'sex': [],'work': [],'kids': [],'pc': []}

then using something like

freq={}

for k,v in results:
    for i in set(v): freq[k]=v.count(i)

Answer 2

Three main things to look at.

• Print. if you want to see an output you are going to need to print.
• Return. Return shoud be inside a function, it doesnt work otherwise.
• Indenting. Indentation is meaningful in python so you need to be careful with it.

Now, i couldn't quite work out the structure of your text file from your question. if you give me a direct example i can show you how to get that code working precisely. However i've added a simple example:

Given a text file like:

50,m,1,0
14,f,0,1
30,f,1,1
90,f,1,0

Representing age, gender, has children, and has pc.

def process_file(filename):
    infile=open(filename, "r")
    Table = [["<=20", 0,0,0,0],[">=20",0,0,0,0]]
    for line in infile:
        columns = line.split(',')
        if(int(columns[0]) <=20):
            if(columns[1]== "m"):
                Table[0][1] += 1
            else:
                Table[0][2] +=1
            Table[0][3] += int(columns[2])
            Table[0][4] += int(columns[3])
        else:
            if(columns[1]== "m"):
                Table[1][1] += 1
            else:
                Table[1][2] +=1
            Table[1][3] += int(columns[2])
            Table[1][4] += int(columns[3])
    return Table

print(process_file("test.txt"))

Gives an output of:

[['<=20',0,1,0,1]['>=20',1,2,3,1]]

Meaning

[Age group, men, women, has kids, has pc]

Improving past base functionality.

Why both my example and your program a very simple it would be considered good design to consider improving your abstractions. Things like the dictionary which has been mentioned will help with this. So would things like classes and objects.

Answer 3

_AGES = (
    (20, "<= 20"),
    (23, "21-23"),
    (26, "24-26"),
    (29, "27-29"),
    (9999, ">= 30"),
)

def age_group(age:int) -> str:
    if age < 0:
        raise ValueError("Age must be a positive number")

    for ai in _AGES:
        if age <= ai[0]:
            return ai[1]

    raise ValueError("Age {} is completely out of range")

def process_file(path, column):

    tabulation = {}

    with open(path, 'r') as infile:

        infile.readline()

        for line in infile:
            columns = line.strip().split(',')
            group = age_group(int(columns[1]))

            if group not in tabulation:
                tabulation[group] = {
                    "count": 0,
                    "sum": 0,
                    "percentage": 0,
                }

            tabgroup = tabulation[group]
            tabgroup['count'] += 1
            tabgroup['sum'] += int(columns[column])
            tabgroup['percentage'] = (100.0 * tabgroup['sum'] / tabgroup['count'])

    return tabulation