PythonQ 240-8XX Uživatelský manuál stáhnout pdf (Strana 17)

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Slices refer the array data

With a as list, a[:] makes a copy of the data

With a as array, a[:] is a reference to the data

>>> b = a[2,:] # extract 2nd row of a

>>> print a[2,0]

12.0

>>> b[0] = 2

>>> print a[2,0]

2.0 # change in b is reflected in a!

Ta ke a c o py t o avo i d r e fe r e n c i n g v i a s l i c e s :

>>> b = a[2,:].copy()

>>> print a[2,0]

12.0

>>> b[0] = 2 # b and a are two different arrays now

>>> print a[2,0]

12.0 # a is not affected by change in b

Numerical Python – p. 251/728

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PythonQ 240-8XX Uživatelský manuál Strana 17