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You're reading from  Scientific Computing with Python 3

Product typeBook
Published inDec 2016
Reading LevelBeginner
PublisherPackt
ISBN-139781786463517
Edition1st Edition
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Authors (3):
Claus Führer
Claus Führer
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Claus Führer

Claus Führer is a professor of scientific computations at Lund University, Sweden. He has an extensive teaching record that includes intensive programming courses in numerical analysis and engineering mathematics across various levels in many different countries and teaching environments. Claus also develops numerical software in research collaboration with industry and received Lund University's Faculty of Engineering Best Teacher Award in 2016.
Read more about Claus Führer

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Type checking


The direct way to see the type of a variable is to use the type command:

label = 'local error'
type(label) # returns str
x = [1, 2] # list
type(x) # returns list

However, if you want to test for a variable to be of a certain type, you should use isinstance (instead of comparing the types with type):

isinstance(x, list) # True

The reason for using isinstance becomes apparent after having read Chapter 8, Classes, and in particular the concept of subclassing and inheritance in section Subclassing and Inheritance in Chapter 8, Classes. In short, often different types share some common properties with some basic type. The classical example is the type bool, which is derived by subclassing from the more general type int. In this situation, we see how the command isinstance  can be used in a more general way:

test = True
isinstance(test, bool) # True
isinstance(test, int) # True
type(test) == int # False
type(test) == bool # True

So, in order to make sure...

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Scientific Computing with Python 3
Published in: Dec 2016Publisher: PacktISBN-13: 9781786463517

Authors (3)

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Claus Führer

Claus Führer is a professor of scientific computations at Lund University, Sweden. He has an extensive teaching record that includes intensive programming courses in numerical analysis and engineering mathematics across various levels in many different countries and teaching environments. Claus also develops numerical software in research collaboration with industry and received Lund University's Faculty of Engineering Best Teacher Award in 2016.
Read more about Claus Führer