PythonQ 240-8XX Instrukcja Użytkownika Pobierz pdf (Strona 23)

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More useful array met hods and attributes

>>> a = zeros(4) + 3

>>> a

array([ 3., 3., 3., 3.]) # float data

>>> a.item(2) # more efficient than a[2]

3.0

>>> a.itemset(3,-4.5) # more efficient than a[3]=-4.5

>>> a

array([ 3. , 3. , 3. , -4.5])

>>> a.shape = (2,2)

>>> a

array([[ 3. , 3. ],

[3.,-4.5]])

>>> a.ravel() # from multi-dim to one-dim

array([ 3. , 3. , 3. , -4.5])

>>> a.ndim # no of dimensions

>>> len(a.shape) # no of dimensions

>>> rank(a) # no of dimensions

>>> a.size # total no of elements

>>> b = a.astype(int) # change data type

>>> b

array([3, 3, 3, 3])

Numerical Python – p. 257/728

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PythonQ 240-8XX Instrukcja Użytkownika Strona 23