从文件中读取并作为字典返回的函数？答案

【问题标题】：Function to read from a file and return as a dictionary?从文件中读取并作为字典返回的函数？
【发布时间】：2016-11-13 19:12:47
【问题描述】：

学习 python 并且无法理解如何创建此函数来读取文件并将其作为字典返回。我知道我需要打开文件然后使用 .read()，但到目前为止我不确定如何对数据进行排序。由于会有多个“标题”，我试图将大写字母排序在所有小写字母之前。关于如何进行的任何建议？

到目前为止我的代码：

def read_text(textname):
    d = {}
    with open(textname) as f:
        for line in f:
            (title, year, height, width, media, country) = line.split() # I need to skip the first line in the file as well which just shows the categories.

文本文件示例：

text0='''"Artist","Title","Year","Total Height","Total 
Width","Media","Country"
"Leonardo da Vinci","Mona Lisa","1503","76.8","53.0","oil paint","France"
"Leonardo da Vinci","The Last Supper","1495","460.0","880.0","tempera","Italy"

我想要返回的文件为：

{'Leonardo da Vinci': [("Mona Lisa",1503,76.8,53.0,"oil paint","France"),
('The Last Supper', 1495, 460.0, 880.0, 'tempera', 'Italy')]}

【问题讨论】：

@UnholySheep 这是一个 csv 文件
发生了什么事？ - 关于这个特定问题有more 和more 问题...
Sort a Python dictionary by value的可能重复
您在为哪一部分苦苦挣扎？看起来您甚至没有尝试创建字典或返回任何内容。

标签： python python-3.x dictionary

【解决方案1】：

一种方法是使用csv 模块和setdefault 方法dicts：

>>> import csv
>>> with open('data.csv') as f:
...   d = {}
...   reader = csv.reader(f)
...   header = next(f) # skip first line, save it if you want to
...   for line in reader:
...     artist, *rest = line
...     d.setdefault(artist,[]).append(tuple(rest))
... 
>>> d
{'Leonardo da Vinci': [('Mona Lisa', '1503', '76.8', '53.0', 'oil paint', 'France'), ('The Last Supper', '1495', '460.0', '880.0', 'tempera', 'Italy')]}

更pythonic的方式是使用defaultdict：

>>> from collections import defaultdict
>>> with open('data.csv') as f:
...   d = defaultdict(list)
...   reader = csv.reader(f)
...   header = next(f) # skip header
...   for line in reader:
...     artist, *rest = line
...     d[artist].append(rest)
... 
>>> d
defaultdict(<class 'list'>, {'Leonardo da Vinci': [('Mona Lisa', '1503', '76.8', '53.0', 'oil paint', 'France'), ('The Last Supper', '1495', '460.0', '880.0', 'tempera', 'Italy')]})
>>>

找出获得所需数据类型的最佳方法留作练习......显然这一切都是从一开始就完成的。

【讨论】：

【解决方案2】：

您的输入文件是 CSV 文件（逗号分隔值）。有一个名为 csv 的模块用于阅读它们。

import csv
import ast
def our_function(filename):
    output = {}
    with open(filename) as f:
        r = csv.reader(f)
        _ = next(r) #ignore the first line
        for line in r:
             head, *tail = map(ast.literal_eval, line) #make values the right types
             if head in output:
                 output[head].append(tuple(tail))
             else:
                 output[head] = [tuple(tail)]
    return output

ast.literal_eval 将接受'"Mona Lisa"'、'1234' 等输入并返回'Mona Lisa' 和1234 等输出

【讨论】：

【解决方案3】：

使用csv.reader对象和enumerate函数的解决方案：

import csv

picture_info = {}
# let's say: `pictures.csv` is your initial file
with open('pictures.csv', 'r', newline='\n') as fh:
    r = csv.reader(fh)
    for k, line in enumerate(r):
        if k == 0: continue
        if not picture_info.get(line[0], None):
            picture_info[line[0]] = [tuple(line[1:])]
        else:
            picture_info[line[0]].append(tuple(line[1:]))

print(picture_info)

输出：

{'Leonardo da Vinci': [('Mona Lisa', '1503', '76.8', '53.0', 'oil paint', 'France'), ('The Last Supper', '1495', '460.0', '880.0', 'tempera', 'Italy')]}

【讨论】：