关联来自两个 CSV 的数据并使用 Python 将数据写入第一个 CSV

Question

我不知道从哪里开始研究这个个人项目，我希望这个社区可以帮助我创建一个 Python 脚本来处理这些数据。

我有一个 CSV 文件，其中包含在动物救援中喂给狗的食物列表，并与狗窝编号相关联：

源 CSV - mealandtreats.csv

blank_column,Kennel_Number,Species,Food,Meal_ID
,1,Dog,Meal,11.2
,5,Dog,Meal,45.2
,3,Dog,Meal,21.4
,4,Dog,Meal,17
,2,Dog,Meal,11.2
,4,Dog,Meal,21.4
,6,Dog,Meal,17
,2,Dog,Meal,45.2

我有第二个 CSV 文件，它提供了一个键，用于将餐食与餐食搭配：

Meal to Treat Key - MealsToTreatsKey.csv

Meals_fed,Treats_fed
10.1,2.4
11.2,2.4
13.5,3
15.6,3.2
17,3.2
20.1,5.1
21.4,5.2
35.7,7.7
45.2,7.9

我需要获取表 1 中提供的每种餐食类型（例如，删除重复条目），找到相关的零食类型，然后为每次向特定狗舍提供零食时创建一个单独的条目。最终结果应该是这样的：

结果 CSV - mealandtreats.csv

blank_column,Kennel_Number,Species,Food,Meal_ID
,1,Dog,Meal,11.2
,5,Dog,Meal,45.2
,3,Dog,Meal,21.4
,4,Dog,Meal,17
,2,Dog,Meal,11.2
,4,Dog,Meal,21.4
,6,Dog,Meal,17
,2,Dog,Meal,45.2
,1,Dog,Treat,2.4
,5,Dog,Treat,7.9
,3,Dog,Treat,5.2
,4,Dog,Treat,3.2
,1,Dog,Treat,2.4
,4,Dog,Treat,5.2

我更愿意使用 csv 模块而不是 Pandas，但我愿意在必要时使用 Pandas。

到目前为止，我有一些代码只是打开 CSV，但我真的不知道下一步该去哪里：

import csv

with open('./meals/results/foodToTreats.csv', 'r') as t1, 
open('./results/food.csv', 'r') as t2:
    key = t1.readlines()
    map = t2.readlines()

with open('./results/food.csv', 'w') as outFileF:
        for line in map:
            if line not in key:
                outFileF.write(line)

with open('./results/foodandtreats.csv', 'w') as outFileFT:
        for line in map:
            if line not in key:
                outFileFT.write(line)

所以基本上我只需要获取第二张表中的每个零食条目，在第一张表中搜索匹配的相关食品条目，查找与该条目相关的犬舍编号，然后将其写入第一张表。

用伪代码尽力而为，例如：

for x in column 0,y: 
    y,1 = Z 

food = x
treat = y
kennel_number = z

when x,z: 
    writerows('', {'kennel_number"}, 'species', '{food/treat}',  
{'meal_id"})

更新：感谢@wwii，这是我正在使用的确切代码。看到一个小错误：

import csv
import collections

treats = {}
with open('mealsToTreatsKey.csv') as f2:
    for line in f2:
        meal,treat = line.strip().split(',')
        treats[meal] = treat

new_items = set()
Treat = collections.namedtuple('Treat', ['blank_column','Kennel_Number','Species','Food','Meal_ID'])

with open('foodandtreats.csv') as f1:
    reader = csv.DictReader(f1)
    for row in reader:
        row['Food'] = 'Treat'
        row['Meal_ID'] = treats[row['Meal_ID']]
        new_items.add(Treat(**row))
    fieldnames = reader.fieldnames

with open('foodandtreats.csv', 'a') as f1:
    writer = csv.DictWriter(f1, fieldnames)
    for row in new_items:
        writer.writerow(row._asdict())

除了一个小错误之外，这非常有效。写入的第一个新行不是从它自己的行开始： enter image description here

Answer 1

制作一个字典，将食物映射到零食

treats = {}
with open(treatfile) as f2:
    for line in f2:
        meal,treat = line.strip().split(',')
        treats[meal] = treat

遍历膳食文件并创建一组新条目。对新项目使用 namedtuples。

import collections
new_items = set()
Treat = collections.namedtuple('Treat', ['blank_column','Kennel_Number','Species','Food','Meal_ID'])

with open(mealfile) as f1:
    reader = csv.DictReader(f1)
    for row in reader:
        row['Food'] = 'Treat'
        row['Meal_ID'] = treats[row['Meal_ID']]
        new_items.add(Treat(**row))
    fieldnames = reader.fieldnames

（再次）打开膳食文件以添加和写入新条目

with open(mealfile, 'a') as f1:
    writer = csv.DictWriter(f1, fieldnames)
    for row in new_items:
        writer.writerow(row._asdict())

---

如果餐文件不以换行符结尾，您需要在写入新的treat 行之前添加一个。由于您可以控制文件，因此您应该确保它始终以空行结尾。