小编ajk*_*hol的帖子

我正在尝试计算具有以下方程式的矩阵。

S = (D^?1/2) * W * (D^?1/2)

其中D是这种形式的对角矩阵：

array([[ 0.59484625,  0.        ,  0.        ,  0.        ],
       [ 0.        ,  0.58563893,  0.        ,  0.        ],
       [ 0.        ,  0.        ,  0.58280472,  0.        ],
       [ 0.        ,  0.        ,  0.        ,  0.58216725]])

和W：

array([[ 0.        ,  0.92311635,  0.94700586,  0.95599748],
       [ 0.92311635,  0.        ,  0.997553  ,  0.99501248],
       [ 0.94700586,  0.997553  ,  0.        ,  0.9995501 ],
       [ 0.95599748,  0.99501248,  0.9995501 ,  0.        ]])

我试图D^-1/2通过使用numpyfunction linalg.matrix_power(D,-1/2) …

我是Python的新手我正在尝试一个小的随机时间生成器,它从给定的初始化变量生成随机时间,并以1000条记录的给定结束变量结束,并且必须将这1000条记录保存到数据库中.

我到目前为止已经达到了这个代码.

SQL.py

from sqlalchemy import create_engine, Column, Integer
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

engine = create_engine('sqlite:///sql.sqlite')
Base = declarative_base()
Session = sessionmaker(bind=engine)

session = Session()

class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    time = Column(Integer, default=None, index=True)

Base.metadata.create_all(engine)

Random.py

import datetime
import time
import random


MINTIME = datetime.datetime(2010,8,6,8,14,59)
MAXTIME = datetime.datetime(2013,8,6,8,14,59)
RECORDS = 1000

for RECORD in range(RECORDS):
    RANDOMTIME = random.randint(MINTIME, MAXTIME)
    print RANDOMTIME

它会产生回溯

TypeError: unsupported operand type(s) for +: 'datetime.datetime' and 'int' …

我试图找出Python中的生成器,我试图过滤列表并对它们进行平方并返回输出.

list = [1, 4, -5, 10, -7, 2, 3, -1]

def square_generator(optional_parameter):
    return (x ** 2 for x in list if x > optional_parameter)
g = (square_generator(i) for i in list)

h = square_generator(0)
print h

我做错了什么？

我有这样的字典

data = {
    'a': [95, 93, 90],
    'b': [643, 611, 610]
}

我想迭代dict并从每个项的值列表中获取键和值,类似这样

{'a': 95, 'b': 643}
{'a': 93, 'b': 611}
{'a': 90, 'b': 610}

我已经为此实现了逻辑并且它工作正常,但是当我看到正在temp_dict创建的过程中,我看到许多中间不必要的循环.最终的结果很好,但我认为它可以改进很多.

import timeit

data = {
    'a': [95, 93, 90],
    'b': [643, 611, 610]
}


def calculate(**kwargs):
    temp_dict = {}
    index = 0
    len_values = list(kwargs.values())[0]

    while index < len(len_values):
        for k, v in kwargs.items():
            temp_dict[k] = v[index]
        index += 1
        yield temp_dict


start_time = timeit.default_timer()
for k in (calculate(**data)):
    print(k)
print(timeit.default_timer() …

假设我有一个名为A的类,我想列出从该特定类创建的所有对象.这是我到目前为止所做的,它提出了AttributeError: type object 'A' has no attribute 'items'如何做到这一点？

class A:
    def __init__(self):
        self.items = []
        self.items.append(self)

    @classmethod
    def list_objects(cls):
        return cls.items


a = A()
b = A()
print(A.list_objects())

# Expected output is [a,b]

我正在使用Django 1.5.4

我是Django的新手,我试图显示通过管理面板上传的图像,但遗憾的是图像源代码中的url字段为空,如果我更改{{ article.image.url }}为{{ article.image }},则图像网址显示为

<img src="media/abyss.jpg" alt="" height="450"/> 

当我点击图片链接时,它说

TypeError at /media/abyss.jpg
can only concatenate tuple (not "unicode") to tuple

请帮我.

Settings.py文件

 MEDIA_ROOT = (os.path.join(os.path.dirname(__file__), '..', 'media').replace('\\','/'),)
 MEDIA_URL = '/media/'

Models.py文件

class Article(models.Model):
    title = models.CharField(max_length=255)
    slug = models.SlugField(unique=True, max_length=255)
    description = models.TextField()
    content = models.TextField()
    published = models.BooleanField(default=True)
    image = models.ImageField(upload_to='media', blank=True)
    created = models.DateTimeField(auto_now_add=True)


   def __unicode__(self):
       return u'%s' % self.title

   class Meta:
      ordering = ['-created']

   def get_absolute_url(self):
      return …

我试图Rainbow Tables用密码加密来解决这个问题,并且只是到目前为止.

import sys
import random
import hashlib

def mt_rand (low = 0, high = sys.maxint):
    """Generate a better random value
    """
    return random.randint (low, high)

def substr (s, start, length = None):
    """Returns the portion of string specified by the start and length
    parameters.
    """
    if len(s) >= start:
        return False
    if not length:
        return s[start:]
    elif length > 0:
        return s[start:start + length]
    else:
        return s[start:length]

def unique_salt():
    return substr(hashlib.sha1(mt_rand()),0,22)

password = "12345"
salt = unique_salt() …

d = {
    "key": "Impress the playing crowd with these classic "
           "Playing Cards \u00a9 Personalized Coasters.These beautiful"
           " coasters are made from glass, and measure approximately 4\u201d x 4\u201d (inches)"
           ".Great to look at, and lovely to the touch.There are 4 coasters in a set.We have "
           "created this exclusive design for all card lovers.Each coaster is a different suit, "
           "with the underneath.Make your next Bridge, or Teen Patti session uber-personal!"
           "Will look great on the bar, or …

我试图根据这些表中的技能查询用户.

class User(UserMixin, db.Model):
    __tablename__ = 'users'

    id = db.Column(db.Integer, primary_key=True)
    email = db.Column(db.String(64), unique=True, index=True)
    username = db.Column(db.String(64), unique=True, index=True)
    skills = db.relationship('Skill', backref='author', lazy='dynamic')

class Skill(db.Model):
    __tablename__ = 'skills'

    id = db.Column(db.Integer, primary_key=True)
    skill = db.Column(db.String(64), index=True)
    author_id = db.Column(db.Integer, db.ForeignKey('users.id'))

我在用户表中尝试了这个并得到了这个错误.

@classmethod
def users_by_skill(cls, skill):
    return User.query.join(Skill).filter(skill.skill).all()

AttributeError: 'str' object has no attribute 'skill'

我错过了哪里？

我正在尝试对文件名进行哈希处理，然后保存到数据库中。我正在使用 Flask 和 Python 3.4

这是上传代码：

@app.route('/', methods=['GET', 'POST'])
def upload_pic():
    if request.method == 'POST':
        file = request.files['file']
        try:
            extension = file.filename.rsplit('.', 1)[1].lower()
        except IndexError as e:
            abort(404)
        if file and check_extension(extension):
            # Salt and hash the file contents
            filename = md5(file.read() + str(round(time.time() * 1000))).hexdigest() + '.' + extension
            file.seek(0)  # Move cursor back to beginning so we can write to disk
            file.save(os.path.join(app.config['UPLOAD_DIR'], filename))
            add_pic(filename)
            gen_thumbnail(filename)
            return redirect(url_for('show_pic', filename=filename))
        else:  # Bad file extension
            abort(404)
    else:
        return render_template('upload.html')

当我发布表单时，我收到此错误回溯。 …