What is lambda? How can you explain this sorting [duplicate]

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-7

This question already has an answer here:

• 
  Syntax behind sorted(key=lambda: …)
  
  6 answers
  
  


• 
  Why are Python lambdas useful? [closed]
  
  26 answers
  
  

Please be gentle I'm still learning Python. I've an example where

pairs = [(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]

pairs.sort(key=lambda pair: pair[1])

The result is

[(4, 'four'), (1, 'one'), (3, 'three'), (2, 'two')]

Can you please help explain why this is the sequence?

python lambda

share|improve this question

asked Jan 3 at 15:13

MilkyMilky

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Jan 3 at 15:20

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  A lambda is an anonymous function: docs.python.org/3/tutorial/controlflow.html#lambda-expressions
  
  – UnholySheep
  Jan 3 at 15:15
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  lambda is the same as an unnamed function, i.e. def f(pair): return pair[1]. You will do well to brush up on the vast documentations and tutorials on beginner basics of Python before venturing further...
  
  – Idlehands
  Jan 3 at 15:15
  
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Give this post a look
  
  – yatu
  Jan 3 at 15:16
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  All functions are anonymous; the def statement simply binds the function to a name after it has been defined. A lambda expression is an expression (rather than a statement) that can create a function as long as the body of the function is itself a single expression.
  
  – chepner
  Jan 3 at 15:16
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Adding to what was already said : you are establishing a criteria on how to sort. The lambda function returns the second element for each tuple. Therefore, you are sorting by the second element of your tuples.
  
  – Matina G
  Jan 3 at 15:18
  

  
  
  
  

 | 
show 2 more comments

-7

This question already has an answer here:

• 
  Syntax behind sorted(key=lambda: …)
  
  6 answers
  
  


• 
  Why are Python lambdas useful? [closed]
  
  26 answers
  
  

Please be gentle I'm still learning Python. I've an example where

pairs = [(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]

pairs.sort(key=lambda pair: pair[1])

The result is

[(4, 'four'), (1, 'one'), (3, 'three'), (2, 'two')]

Can you please help explain why this is the sequence?

python lambda

share|improve this question

asked Jan 3 at 15:13

MilkyMilky

1

marked as duplicate by Idlehands, coldspeed python
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Jan 3 at 15:20

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  A lambda is an anonymous function: docs.python.org/3/tutorial/controlflow.html#lambda-expressions
  
  – UnholySheep
  Jan 3 at 15:15
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  lambda is the same as an unnamed function, i.e. def f(pair): return pair[1]. You will do well to brush up on the vast documentations and tutorials on beginner basics of Python before venturing further...
  
  – Idlehands
  Jan 3 at 15:15
  
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Give this post a look
  
  – yatu
  Jan 3 at 15:16
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  All functions are anonymous; the def statement simply binds the function to a name after it has been defined. A lambda expression is an expression (rather than a statement) that can create a function as long as the body of the function is itself a single expression.
  
  – chepner
  Jan 3 at 15:16
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Adding to what was already said : you are establishing a criteria on how to sort. The lambda function returns the second element for each tuple. Therefore, you are sorting by the second element of your tuples.
  
  – Matina G
  Jan 3 at 15:18
  

  
  
  
  

 | 
show 2 more comments

-7

-7

-7

This question already has an answer here:

• 
  Syntax behind sorted(key=lambda: …)
  
  6 answers
  
  


• 
  Why are Python lambdas useful? [closed]
  
  26 answers
  
  

Please be gentle I'm still learning Python. I've an example where

pairs = [(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]

pairs.sort(key=lambda pair: pair[1])

The result is

[(4, 'four'), (1, 'one'), (3, 'three'), (2, 'two')]

Can you please help explain why this is the sequence?

python lambda

share|improve this question

asked Jan 3 at 15:13

MilkyMilky

1

This question already has an answer here:

• 
  Syntax behind sorted(key=lambda: …)
  
  6 answers
  
  


• 
  Why are Python lambdas useful? [closed]
  
  26 answers
  
  

Please be gentle I'm still learning Python. I've an example where

pairs = [(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]

pairs.sort(key=lambda pair: pair[1])

The result is

[(4, 'four'), (1, 'one'), (3, 'three'), (2, 'two')]

Can you please help explain why this is the sequence?

This question already has an answer here:

• 
  Syntax behind sorted(key=lambda: …)
  
  6 answers
  
  


• 
  Why are Python lambdas useful? [closed]
  
  26 answers
  
  

python lambda

python lambda

share|improve this question

asked Jan 3 at 15:13

MilkyMilky

1

share|improve this question

asked Jan 3 at 15:13

MilkyMilky

1

share|improve this question

share|improve this question

asked Jan 3 at 15:13

MilkyMilky

1

asked Jan 3 at 15:13

MilkyMilky

1

asked Jan 3 at 15:13

MilkyMilky

1

1

marked as duplicate by Idlehands, coldspeed python
Users with the  python badge can single-handedly close python questions as duplicates and reopen them as needed.

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Jan 3 at 15:20

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

marked as duplicate by Idlehands, coldspeed python
Users with the  python badge can single-handedly close python questions as duplicates and reopen them as needed.

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Jan 3 at 15:20

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  A lambda is an anonymous function: docs.python.org/3/tutorial/controlflow.html#lambda-expressions
  
  – UnholySheep
  Jan 3 at 15:15
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  lambda is the same as an unnamed function, i.e. def f(pair): return pair[1]. You will do well to brush up on the vast documentations and tutorials on beginner basics of Python before venturing further...
  
  – Idlehands
  Jan 3 at 15:15
  
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Give this post a look
  
  – yatu
  Jan 3 at 15:16
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  All functions are anonymous; the def statement simply binds the function to a name after it has been defined. A lambda expression is an expression (rather than a statement) that can create a function as long as the body of the function is itself a single expression.
  
  – chepner
  Jan 3 at 15:16
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Adding to what was already said : you are establishing a criteria on how to sort. The lambda function returns the second element for each tuple. Therefore, you are sorting by the second element of your tuples.
  
  – Matina G
  Jan 3 at 15:18
  

  
  
  
  

 | 
show 2 more comments

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  A lambda is an anonymous function: docs.python.org/3/tutorial/controlflow.html#lambda-expressions
  
  – UnholySheep
  Jan 3 at 15:15
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  lambda is the same as an unnamed function, i.e. def f(pair): return pair[1]. You will do well to brush up on the vast documentations and tutorials on beginner basics of Python before venturing further...
  
  – Idlehands
  Jan 3 at 15:15
  
  
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  Give this post a look
  
  – yatu
  Jan 3 at 15:16
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  All functions are anonymous; the def statement simply binds the function to a name after it has been defined. A lambda expression is an expression (rather than a statement) that can create a function as long as the body of the function is itself a single expression.
  
  – chepner
  Jan 3 at 15:16
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Adding to what was already said : you are establishing a criteria on how to sort. The lambda function returns the second element for each tuple. Therefore, you are sorting by the second element of your tuples.
  
  – Matina G
  Jan 3 at 15:18
  

  
  
  
  

A lambda is an anonymous function: docs.python.org/3/tutorial/controlflow.html#lambda-expressions

– UnholySheep
Jan 3 at 15:15

A lambda is an anonymous function: docs.python.org/3/tutorial/controlflow.html#lambda-expressions

– UnholySheep
Jan 3 at 15:15

lambda is the same as an unnamed function, i.e. def f(pair): return pair[1]. You will do well to brush up on the vast documentations and tutorials on beginner basics of Python before venturing further...

– Idlehands
Jan 3 at 15:15

lambda is the same as an unnamed function, i.e. def f(pair): return pair[1]. You will do well to brush up on the vast documentations and tutorials on beginner basics of Python before venturing further...

– Idlehands
Jan 3 at 15:15

1

1

Give this post a look

– yatu
Jan 3 at 15:16

Give this post a look

– yatu
Jan 3 at 15:16

All functions are anonymous; the def statement simply binds the function to a name after it has been defined. A lambda expression is an expression (rather than a statement) that can create a function as long as the body of the function is itself a single expression.

– chepner
Jan 3 at 15:16

All functions are anonymous; the def statement simply binds the function to a name after it has been defined. A lambda expression is an expression (rather than a statement) that can create a function as long as the body of the function is itself a single expression.

– chepner
Jan 3 at 15:16

Adding to what was already said : you are establishing a criteria on how to sort. The lambda function returns the second element for each tuple. Therefore, you are sorting by the second element of your tuples.

– Matina G
Jan 3 at 15:18

Adding to what was already said : you are establishing a criteria on how to sort. The lambda function returns the second element for each tuple. Therefore, you are sorting by the second element of your tuples.

– Matina G
Jan 3 at 15:18

 | 
show 2 more comments

1 Answer
1

active

oldest

votes

0

A lambda is simply a short way of declaring a simple function. That code could just as easily have been written:

pairs = [(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]



def key_func(pair):

    return pair[1]



pairs.sort(key=key_func)

In this case, the lambda function is telling sort how it should turn a value in the array (in this case, a tuple which doesn't have an obvious sorting order) into a value that it knows how to sort (a string).

share|improve this answer

answered Jan 3 at 15:19

Harry CuttsHarry Cutts

1,098921

add a comment | 

1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

active

oldest

votes

active

oldest

votes

0

A lambda is simply a short way of declaring a simple function. That code could just as easily have been written:

pairs = [(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]



def key_func(pair):

    return pair[1]



pairs.sort(key=key_func)

In this case, the lambda function is telling sort how it should turn a value in the array (in this case, a tuple which doesn't have an obvious sorting order) into a value that it knows how to sort (a string).

share|improve this answer

answered Jan 3 at 15:19

Harry CuttsHarry Cutts

1,098921

add a comment | 

0

A lambda is simply a short way of declaring a simple function. That code could just as easily have been written:

pairs = [(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]



def key_func(pair):

    return pair[1]



pairs.sort(key=key_func)

In this case, the lambda function is telling sort how it should turn a value in the array (in this case, a tuple which doesn't have an obvious sorting order) into a value that it knows how to sort (a string).

share|improve this answer

answered Jan 3 at 15:19

Harry CuttsHarry Cutts

1,098921

add a comment | 

0

0

0

A lambda is simply a short way of declaring a simple function. That code could just as easily have been written:

pairs = [(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]



def key_func(pair):

    return pair[1]



pairs.sort(key=key_func)

In this case, the lambda function is telling sort how it should turn a value in the array (in this case, a tuple which doesn't have an obvious sorting order) into a value that it knows how to sort (a string).

share|improve this answer

answered Jan 3 at 15:19

Harry CuttsHarry Cutts

1,098921

A lambda is simply a short way of declaring a simple function. That code could just as easily have been written:

pairs = [(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')]



def key_func(pair):

    return pair[1]



pairs.sort(key=key_func)

In this case, the lambda function is telling sort how it should turn a value in the array (in this case, a tuple which doesn't have an obvious sorting order) into a value that it knows how to sort (a string).

share|improve this answer

answered Jan 3 at 15:19

Harry CuttsHarry Cutts

1,098921

share|improve this answer

share|improve this answer

answered Jan 3 at 15:19

Harry CuttsHarry Cutts

1,098921

answered Jan 3 at 15:19

Harry CuttsHarry Cutts

1,098921

answered Jan 3 at 15:19

Harry CuttsHarry Cutts

1,098921

1,098921

add a comment | 

add a comment | 

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