search
Search
Join our weekly DS/ML newsletter layers DS/ML Guides
menu
menu search toc more_vert
Robocat
Guest 0reps
Thanks for the thanks!
close
chevron_left Documentation
Method argpartition
NumPy Random Generator4 topics
Method choiceMethod dotMethod finfoMethod histogramMethod iinfoMethod maxMethod meanMethod placeMethod rootsMethod seedMethod uniformMethod viewMethod zerosMethod sumObject busdaycalendarMethod is_busdayProperty dtypeMethod uniqueMethod loadtxtMethod vsplitMethod fliplrMethod setdiff1dMethod msortMethod argsortMethod lexsortMethod aroundMethod nanmaxMethod nanminMethod nanargmaxMethod nanargminMethod argmaxMethod argminProperty itemsizeMethod spacingMethod fixMethod ceilMethod diffProperty flatProperty realProperty baseMethod flipMethod deleteMethod amaxMethod aminMethod logical_xorMethod logical_orMethod logical_notMethod logical_andMethod logaddexpMethod logaddexp2Method logspaceMethod not_equalMethod equalMethod greater_equalMethod lessMethod less_equalMethod remainderMethod modMethod emptyMethod greaterMethod isfiniteMethod busday_countMethod repeatMethod varMethod random_sampleMethod randomMethod signMethod stdMethod absoluteMethod absMethod sortMethod randintMethod isrealMethod linspaceMethod gradientMethod allMethod sampleProperty TProperty imagMethod covMethod insertMethod logMethod log1pMethod exp2Method expm1Method expMethod arccosMethod cosMethod arcsinMethod sinMethod tanMethod fromiterMethod trim_zerosMethod diagflatMethod savetxtMethod count_nonzeroProperty sizeProperty shapeMethod reshapeMethod resizeMethod triuMethod trilMethod eyeMethod arangeMethod fill_diagonalMethod tileMethod saveMethod transposeMethod swapaxesMethod meshgridProperty mgridMethod rot90Method log2Method radiansMethod deg2radMethod rad2degMethod degreesMethod log10Method appendMethod cumprodProperty nbytesMethod tostringProperty dataMethod modfMethod fmodMethod tolistMethod datetime_as_stringMethod datetime_dataMethod array_splitMethod itemsetMethod floorMethod put_along_axisMethod cumsumMethod bincountMethod putMethod putmaskMethod takeMethod hypotMethod sqrtMethod squareMethod floor_divideMethod triMethod signbitMethod flattenMethod ravelMethod rollMethod isrealobjMethod diagMethod diagonalMethod quantileMethod onesMethod iscomplexobjMethod iscomplexMethod isscalarMethod divmodMethod isnatMethod percentileMethod isnanMethod divideMethod addMethod reciprocalMethod positiveMethod subtractMethod medianMethod isneginfMethod isposinfMethod float_powerMethod powerMethod negativeMethod maximumMethod averageMethod isinfMethod multiplyMethod busday_offsetMethod identityMethod interpMethod squeezeMethod get_printoptionsMethod savez_compressedMethod savezMethod loadMethod asfarrayMethod clipMethod arrayMethod array_equivMethod array_equalMethod frombufferMethod set_string_functionMethod matmulMethod genfromtxtMethod fromfunctionMethod asscalarMethod searchsortedMethod full_likeMethod fullMethod shares_memoryMethod ptpMethod digitizeMethod argwhereMethod geomspaceMethod zeros_likeMethod fabsMethod flatnonzeroMethod vstackMethod dstackMethod fromstringMethod tobytesMethod expand_dimsMethod ranfMethod arctanMethod itemMethod extractMethod compressMethod chooseMethod asarrayMethod asmatrixMethod allcloseMethod iscloseMethod anyMethod corrcoefMethod truncMethod prodMethod crossMethod true_divideMethod hsplitMethod splitMethod rintMethod ediff1dMethod lcmMethod gcdMethod cbrtMethod flipudProperty ndimMethod array2stringMethod set_printoptionsMethod whereMethod hstack
Char32 topics
Comments
Log in or sign up
Cancel
Post
account_circle
Profile
exit_to_app
Sign out
help Ask a question
Share on Twitter
search
keyboard_voice
close
Searching Tips
Search for a recipe:
"Creating a table in MySQL"
Search for an API documentation: "@append"
Search for code: "!dataframe"
Apply a tag filter: "#python"
Useful Shortcuts
/ to open search panel
Esc to close search panel
to navigate between search results
d to clear all current filters
Enter to expand content preview
icon_star
Doc Search
icon_star
Code Search Beta
SORRY NOTHING FOUND!
mic
Start speaking...
Voice search is only supported in Safari and Chrome.
Navigate to
A
A
brightness_medium
share
arrow_backShare
Twitter
Facebook
chevron_left Documentation
Method argpartition
NumPy Random Generator4 topics
Method choiceMethod dotMethod finfoMethod histogramMethod iinfoMethod maxMethod meanMethod placeMethod rootsMethod seedMethod uniformMethod viewMethod zerosMethod sumObject busdaycalendarMethod is_busdayProperty dtypeMethod uniqueMethod loadtxtMethod vsplitMethod fliplrMethod setdiff1dMethod msortMethod argsortMethod lexsortMethod aroundMethod nanmaxMethod nanminMethod nanargmaxMethod nanargminMethod argmaxMethod argminProperty itemsizeMethod spacingMethod fixMethod ceilMethod diffProperty flatProperty realProperty baseMethod flipMethod deleteMethod amaxMethod aminMethod logical_xorMethod logical_orMethod logical_notMethod logical_andMethod logaddexpMethod logaddexp2Method logspaceMethod not_equalMethod equalMethod greater_equalMethod lessMethod less_equalMethod remainderMethod modMethod emptyMethod greaterMethod isfiniteMethod busday_countMethod repeatMethod varMethod random_sampleMethod randomMethod signMethod stdMethod absoluteMethod absMethod sortMethod randintMethod isrealMethod linspaceMethod gradientMethod allMethod sampleProperty TProperty imagMethod covMethod insertMethod logMethod log1pMethod exp2Method expm1Method expMethod arccosMethod cosMethod arcsinMethod sinMethod tanMethod fromiterMethod trim_zerosMethod diagflatMethod savetxtMethod count_nonzeroProperty sizeProperty shapeMethod reshapeMethod resizeMethod triuMethod trilMethod eyeMethod arangeMethod fill_diagonalMethod tileMethod saveMethod transposeMethod swapaxesMethod meshgridProperty mgridMethod rot90Method log2Method radiansMethod deg2radMethod rad2degMethod degreesMethod log10Method appendMethod cumprodProperty nbytesMethod tostringProperty dataMethod modfMethod fmodMethod tolistMethod datetime_as_stringMethod datetime_dataMethod array_splitMethod itemsetMethod floorMethod put_along_axisMethod cumsumMethod bincountMethod putMethod putmaskMethod takeMethod hypotMethod sqrtMethod squareMethod floor_divideMethod triMethod signbitMethod flattenMethod ravelMethod rollMethod isrealobjMethod diagMethod diagonalMethod quantileMethod onesMethod iscomplexobjMethod iscomplexMethod isscalarMethod divmodMethod isnatMethod percentileMethod isnanMethod divideMethod addMethod reciprocalMethod positiveMethod subtractMethod medianMethod isneginfMethod isposinfMethod float_powerMethod powerMethod negativeMethod maximumMethod averageMethod isinfMethod multiplyMethod busday_offsetMethod identityMethod interpMethod squeezeMethod get_printoptionsMethod savez_compressedMethod savezMethod loadMethod asfarrayMethod clipMethod arrayMethod array_equivMethod array_equalMethod frombufferMethod set_string_functionMethod matmulMethod genfromtxtMethod fromfunctionMethod asscalarMethod searchsortedMethod full_likeMethod fullMethod shares_memoryMethod ptpMethod digitizeMethod argwhereMethod geomspaceMethod zeros_likeMethod fabsMethod flatnonzeroMethod vstackMethod dstackMethod fromstringMethod tobytesMethod expand_dimsMethod ranfMethod arctanMethod itemMethod extractMethod compressMethod chooseMethod asarrayMethod asmatrixMethod allcloseMethod iscloseMethod anyMethod corrcoefMethod truncMethod prodMethod crossMethod true_divideMethod hsplitMethod splitMethod rintMethod ediff1dMethod lcmMethod gcdMethod cbrtMethod flipudProperty ndimMethod array2stringMethod set_printoptionsMethod whereMethod hstack
Char32 topics
0
thumb_down
0
chat_bubble_outline
0
auto_stories new
settings

NumPy | choose method

NumPy
chevron_right
Documentation
schedule Jul 1, 2022
Last updated
local_offer PythonNumPy
Tags

Numpy's choose(~) method constructs a new array from a subset of the input array. The way that the subset is chosen is quite unique, and explaining via examples would be far better than via words, so please check out the examples below!

Parameters

1. a | array-like of int

An array of integer indices you want to extract.

2. choices | sequence of arrays

The superset.

3. out | Numpy array | optional

A Numpy array to place the extracted subset.

4. mode | string | optional

How to deal with indices that are out of bounds:

Mode

Description

raise

Throw an error.

wrap

Go through another cycle around the array.

clip

Get the last element of the array.

By default, mode="raise".

Return value

A Numpy array containing the specified subset.

Examples

1D arrays

To extract the 1st and 3rd index from a 1D array:

a = np.array([4,5,6,7])
np.choose([1,3], a)
array([5, 7])

2D arrays

a = np.array([[4,5,6],[7,8,9],[10,11,12]])
np.choose([1,0,1], a)
array([ 7, 5, 9])

Here, we are doing the following in order:

  • extracting the value at the 0th index of the 1+1=2nd array (i.e. [7,8,9]), which is 7.

  • extracting the value at the 1st index of the 0+1=1st array (i.e. [4,5,6]), which is 5.

  • extracting the value at the 2nd index of the 1+1=2nd array (i.e. [7,8,9]), which is 9.

The first argument, [1,0,1], just means that we want to extract a value from array at indexes 1, 0 and 1. The specific value that will be chosen will depend on the ordering:

  • the first element in the resulting array will be the 0th index of the array located at index 1.

  • the second element in the resulting array will be the 1st index of the array located at index 0.

  • and so on.

Here's yet another example to test your understanding:

a = np.array([[4,5,6],[7,8,9],[10,11,12]])
np.choose([2,0,1], a)
array([10, 5, 9])

Different modes

raise

The default parameter value for mode is raise:

a = np.array([7,8,9])
np.choose([4], a, mode="raise")
ValueError: invalid entry in choice array

Here, we get an error because the index we specified (4) is out of bounds.

wrap

a = np.array([7,8,9])
np.choose([4], a, mode="wrap")
array([8])

Here, since the index 4 does not exist, we go through another cycle around the array; 4-3=1st index is then selected.

clip

a = np.array([7,8,9])
np.choose([4], a, mode="clip")
array([9])

Here, since index 4 is out of bounds, we just get the last element of the array, 4.

mail
Join our newsletter for updates on new DS/ML comprehensive guides (spam-free)
robocat
Published by Isshin Inada
Edited by 0 others
Did you find this page useful?
thumb_down
Ask a question or leave a feedback...
0
thumb_down
0
chat_bubble_outline
0
settings
Enjoy our search
Hit / to insta-search docs and recipes!