Zbiory w Python



In [1]:

    
l = [1,2,3,3,3,4,5,44]



In [2]:

    
s = set(l)



In [6]:

    
s.intersection([33,44,1,1])









    Out[6]:





{1, 44}



In [8]:

    
s.union([111,2,3])









    Out[8]:





{1, 2, 3, 4, 5, 44, 111}

nie można indeksować zbioru



In [10]:

    
s[1]









    



---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-10-88de191fe097> in <module>()
----> 1 s[1]

TypeError: 'set' object does not support indexing

ale można iterować po jego elementach



In [11]:

    
for el in s:
    print(el)

sortowanie



In [14]:

    
l = [13,2,3,4]



In [15]:

    
sorted(l)









    Out[15]:





[2, 3, 4, 13]



In [16]:

    
l









    Out[16]:





[13, 2, 3, 4]



In [17]:

    
l.sort()



In [18]:

    
l









    Out[18]:





[2, 3, 4, 13]



In [19]:

    
l.sort(key=lambda x:1/x)



In [20]:

    
l









    Out[20]:





[13, 4, 3, 2]



In [21]:

    
def f(x):
    return 1/x



In [22]:

    
l.sort(key=f)



In [23]:

    
l









    Out[23]:





[13, 4, 3, 2]



In [33]:

    
l = [("a",1),(2,3),(-1,3)]
l









    Out[33]:





[('a', 1), (2, 3), (-1, 3)]



In [34]:

    
def f(x):
    return x[1]



In [32]:

    
l.sort()









    



---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-32-b56eb6767f72> in <module>()
----> 1 l.sort()

TypeError: unorderable types: int() < str()



In [35]:

    
l.sort(key=f)



In [36]:

    
l









    Out[36]:





[('a', 1), (2, 3), (-1, 3)]



In [47]:

    
l = [ (x,y) for x in range(44) for y in range(44) ]



In [48]:

    
def f(X):
    return( X[0]**2+ X[1]**2)



In [49]:

    
l.sort(key=f)



In [50]:

    
%matplotlib inline
import matplotlib.pyplot as plt



In [54]:

    
l1 = l
plt.plot([x_[0] for x_ in l1],[x_[1] for x_ in l1],'o')
l1 = l[:230]
plt.plot([x_[0] for x_ in l1],[x_[1] for x_ in l1],'or')









    Out[54]:





[<matplotlib.lines.Line2D at 0x7f777b826be0>]



In [86]:

    
l = [1,2,3,4,5]
k = -1



In [87]:

    
l[:-k]









    Out[87]:





[1]



In [88]:

    
l[-k:]









    Out[88]:





[2, 3, 4, 5]



In [89]:

    
l[-k:]+l[:-k]









    Out[89]:





[2, 3, 4, 5, 1]



In [ ]:



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