Using Python to export array elements to variables (unpacking)

The problem solved

Elements in an array (list) or tuple need to be exported to N variables.

The solution

Any sequence can be assigned to corresponding variables by simple variable assignment, the only requirement is that the number and structure of the variables must be consistent with the structure of the sequence.

p = (1, 2)
x, y = p
# x = 1
# y = 2
data = ['google', 100.1, (2016, 5, 31]
name, price, date = data
# name = 'google'
# price = 100.1
# date = (2016, 5, 31)
name, price, (year, month, day) = data
# name = 'google'
# price = 100.1
# year = 2016
# month = 5
# day = 31

If the variable structure and element structure are inconsistent, you will encounter the following error:

p = (1, 2)
x, y, z = p
Traceback (most recent call last):
 File "<pyshell#12>", line 1, in <module>
  x, y, z = p
ValueError: not enough values to unpack (expected 3, got 2)

Such operations are not limited to tuples and arrays, and they can also be used in strings. Unpacking supports most common sequences we often use, such as file iteration, various generators, etc.

s = 'Hello'
a,b,c,d,e = s
# a = 'H'
# b = 'e'

If you want to discard some elements during the export process, Python does not support such syntax, but you can specify some rarely used variables to achieve your purpose.

data = ['google', 100.1, (2016, 5, 31]
name, _, (_,month,_) = data
# name = 'google'
# month = '5'
# other fields will be discarded

Summary

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