As keyword in Python | Pythontic.com

Overview:

The as clause in python is used in the following contexts:

Accompanied by the with statement to name the resource being allocated
In the from…import statement and the import statement as a means to bind the module to a name
In the except statement to associate a name to the exception being passed

As keyword in Python

Fig-1: The as keyword in Python

Example 1 - as clause used in import statement:

# as clause used to bind the name np for the numpy module

import numpy as np

radians = np.pi

# calculate sine, cosine and tan values for np.pi radians

sineValue = np.sin(radians)

cosineValue = np.cos(radians)

tanValue = np.tan(radians)

# print the sine, cosine and tan values

print("Sine of %f radians:%f"%(radians, sineValue));

print("Cosine of %f radians:%f"%(radians, cosineValue));

print("Tangent of %f radians:%f"%(radians, tanValue));

Output 1:

Sine of 3.141593 radians:0.000000

Cosine of 3.141593 radians:-1.000000

Tangent of 3.141593 radians:-0.000000

Example 2 - as clause used in from import statement:

# as clause used to bind the name plot, with pyplot module from matplotlib

import numpy as np

from matplotlib import pyplot as plot

sampleSequence = np.arange(0,400,10)

magnitudeSequence = np.sin(2*np.pi*sampleSequence*1/400)

plot.plot(sampleSequence,magnitudeSequence)

plot.title('Sinusoid')

plot.xlabel('Sample')

plot.ylabel('Amplitude')

plot.show()

Output 2:

with open('sample.txt') as fileObject:

fileContents = fileObject.read()

print("Text file contents:")

print(fileContents)

Example 3 - as clause accompanied by the with statement:

with open('sample.txt') as fileObject:

fileContents = fileObject.read()

print("Text file contents:")

print(fileContents)

Output 3:

Text file contents:

sample text

Example 4 – along with except clause:

try:

fileContents = ""

with open('sample.txt') as fileObject:

fileContents = fileObject.read()

print("Text file contents:")

print(fileContents)

except FileNotFoundError as ex:

print(ex)

Output 4:

[Errno 2] No such file or directory: 'sample.txt'