相关疑难解决方法(0)

我想知道是否有一条快捷方式可以在Python列表中列出一个简单的列表.

我可以在for循环中做到这一点,但也许有一些很酷的"单行"？我用reduce尝试了,但是我收到了一个错误.

码

l = [[1, 2, 3], [4, 5, 6], [7], [8, 9]]
reduce(lambda x, y: x.extend(y), l)

错误信息

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 1, in <lambda>
AttributeError: 'NoneType' object has no attribute 'extend'

我有这个代码

from opensky_api import OpenSkyApi

api = OpenSkyApi()
states = api.get_states(bbox=(51.3500, 51.5900, -0.6342, -0.2742))

for s in states.states:
    lat = s.latitude
    print(lat)

输出看起来像这样

51.4775
51.4589
51.4774
51.4774

如何使输出看起来像这样？

[51.4775, 51.4589, 51.4774, 51.4774]

我需要访问文件夹中的所有图像并将其存储在矩阵中.我能够使用matlab完成它,这里是代码:

input_dir = 'C:\Users\Karim\Downloads\att_faces\New Folder';
image_dims = [112, 92];

filenames = dir(fullfile(input_dir, '*.pgm'));
num_images = numel(filenames);

images = [];
for n = 1:num_images
    filename = fullfile(input_dir, filenames(n).name);
    img = imread(filename);
    img = imresize(img,image_dims);   
end

但我需要使用python来完成它,这是我的python代码:

import Image
import os
from PIL import Image
from numpy import *
import numpy as np


#import images
dirname = "C:\\Users\\Karim\\Downloads\\att_faces\\New folder"


#get number of images and dimentions
path, dirs, files = os.walk(dirname).next()
num_images = len(files)
image_file = "C:\\Users\\Karim\\Downloads\\att_faces\\New folder\\2.pgm"
im = Image.open(image_file)
width, height …