Question

我有一个文字文件

Mash,25.50,108.00  
Enhanced,37.50,162.00  
Pellets,30.00,135.00  
Protein Plus,39.00,174.00  
Calcium Plus,39.00,174.00

我将其运行到打印语句中

def readfile():
    textlist = [line.split(',') for line in open("chookfood.txt", 'r')]
    print(','.join([str(lst) for lst in textlist]))

readfile()

它输出此嵌套列表：

['Mash', '25.50', '108.00\n'],['Enhanced', '37.50', '162.00\n'],['Pellets', '30.00', '135.00\n'],['Protein Plus', '39.00', '174.00\n'],['Calcium Plus', '39.00', '174.00']

如何制作打印语句以打印mash [1]。我无法将这些值存储在闲置的python中，所以我需要某种方式来询问如何从mash中打印25.50？

Answer 1

您已经具有包含内容的列表列表。您只需要从函数返回列表，然后使用列表索引访问内容：

<?php

namespace App\Console\Commands;

use Illuminate\Console\Command;
use DB;
use App\Booking;


class Expire extends Command
{

    protected $signature = 'log:demo';


    protected $description = 'changer la date de sortie';


    public function __construct()
    {
        parent::__construct();
    }

    public function handle()
    {
        //
        DB::table('bookings')->whereDate('sortie', '<=', \Carbon\Carbon::now())->update(['statut' => 'disponible']);
    }
}

然后，仅使用列表索引：

<?php

namespace App\Console;
use DB;
use App\Booking;
use \Carbon\Carbon;

use Illuminate\Console\Scheduling\Schedule;
use Illuminate\Foundation\Console\Kernel as ConsoleKernel;

class Kernel extends ConsoleKernel
{

    protected $commands = [
         'App\Console\Commands\Expire'


    ];


    protected function schedule(Schedule $schedule)
    {
        // $schedule->command('inspire')
        //          ->hourly();
        $schedule->command('log:demo')
                 ->everyMinute();
    }


    protected function commands()
    {
        $this->load(__DIR__.'/Commands');

        require base_path('routes/console.php');
    }
}

Answer 2

如果它们是逗号分隔的值，请使用csv模块：

import csv

with open('chookfood.txt') as chookfood:
    rows = csv.reader(chookfood)
    for row in rows:
        print(row[1])

Answer 3

您可以更改初始列表以将其存储在字典中：

def readfile():
    dictionary = { data[0]: [float(data[1], float(data[2])] for data in [line.split(',') for line in open("chookfood.txt", 'r')]
    print(dictionary)

您可以通过编写以下内容来访问Mash的第一个元素：

print(dictionary[“Mash”][0])

如何在从Python中的文本文件生成的嵌套列表中选择列表项

3 个答案: