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Sorting a Numpy array by column not axis [duplicate]

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1

This question already has an answer here:

• 
  Sorting arrays in NumPy by column
  
  9 answers
  
  

I have a numpy array that is equivalent to:

array([[51, 62, 23],
 [24, 45, 16],
 [67, 78, 39]])

Just much bigger. I'm trying to sort by the second column (ie. the number 62, 45, 78) but keep the horizontal elements together. The output I'm trying to get would be:

array([[24, 45, 16],
 [51, 62, 23],
 [67, 78, 39]])

I can't figure out how to do this with np.sort - I don't think this is the correct function for the job (although I'm a bit new to numpy so I might be wrong) - I'm happy to learn a new function, code snippets would be great, but a simple 'use np.blah' would suffice :D

python-3.x numpy sorting

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asked Mar 27 at 3:39

FraserOfSmegFraserOfSmeg

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1

This question already has an answer here:

• 
  Sorting arrays in NumPy by column
  
  9 answers
  
  

I have a numpy array that is equivalent to:

array([[51, 62, 23],
 [24, 45, 16],
 [67, 78, 39]])

Just much bigger. I'm trying to sort by the second column (ie. the number 62, 45, 78) but keep the horizontal elements together. The output I'm trying to get would be:

array([[24, 45, 16],
 [51, 62, 23],
 [67, 78, 39]])

I can't figure out how to do this with np.sort - I don't think this is the correct function for the job (although I'm a bit new to numpy so I might be wrong) - I'm happy to learn a new function, code snippets would be great, but a simple 'use np.blah' would suffice :D

python-3.x numpy sorting

share|improve this question

asked Mar 27 at 3:39

FraserOfSmegFraserOfSmeg

69211 gold badge1414 silver badges2727 bronze badges

marked as duplicate by cs95 numpy
Users with the  numpy badge can single-handedly close numpy questions as duplicates and reopen them as needed.

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Mar 27 at 4:06

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.

add a comment | 

This question already has an answer here:

• 
  Sorting arrays in NumPy by column
  
  9 answers
  
  

I have a numpy array that is equivalent to:

array([[51, 62, 23],
 [24, 45, 16],
 [67, 78, 39]])

Just much bigger. I'm trying to sort by the second column (ie. the number 62, 45, 78) but keep the horizontal elements together. The output I'm trying to get would be:

array([[24, 45, 16],
 [51, 62, 23],
 [67, 78, 39]])

I can't figure out how to do this with np.sort - I don't think this is the correct function for the job (although I'm a bit new to numpy so I might be wrong) - I'm happy to learn a new function, code snippets would be great, but a simple 'use np.blah' would suffice :D

python-3.x numpy sorting

share|improve this question

asked Mar 27 at 3:39

FraserOfSmegFraserOfSmeg

69211 gold badge1414 silver badges2727 bronze badges

array([[51, 62, 23],
 [24, 45, 16],
 [67, 78, 39]])

array([[24, 45, 16],
 [51, 62, 23],
 [67, 78, 39]])

share|improve this question

asked Mar 27 at 3:39

FraserOfSmegFraserOfSmeg

69211 gold badge1414 silver badges2727 bronze badges

share|improve this question

asked Mar 27 at 3:39

FraserOfSmegFraserOfSmeg

69211 gold badge1414 silver badges2727 bronze badges

asked Mar 27 at 3:39

FraserOfSmegFraserOfSmeg

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asked Mar 27 at 3:39

FraserOfSmegFraserOfSmeg

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1 Answer
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If your numpy array is arr, this should work: arr[arr[:,1].argsort()]

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answered Mar 27 at 3:48

JoshJosh

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add a comment | 

1

If your numpy array is arr, this should work: arr[arr[:,1].argsort()]

share|improve this answer

answered Mar 27 at 3:48

JoshJosh

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add a comment | 

1

If your numpy array is arr, this should work: arr[arr[:,1].argsort()]

share|improve this answer

answered Mar 27 at 3:48

JoshJosh

4099 bronze badges

add a comment | 

If your numpy array is arr, this should work: arr[arr[:,1].argsort()]

share|improve this answer

answered Mar 27 at 3:48

JoshJosh

4099 bronze badges

share|improve this answer

answered Mar 27 at 3:48

JoshJosh

4099 bronze badges

answered Mar 27 at 3:48

JoshJosh

4099 bronze badges

answered Mar 27 at 3:48

JoshJosh

4099 bronze badges