Check if numpy array is in list of numpy arrays

Question

I have a list of numpy arrays and a single numpy array. I want to check if that single array is a member of the list.

I suppose there exist a method and I haven't searched properly... This is what I came up with:

def inList(array, list):     for element in list:         if np.array_equal(element, array):             return True     return False 

Is this implementation correct? Is there any ready function for this?

Answer 1

Using the verb is when talking about python is a bit ambiguous. This example covers all the cases I could think of:

from __future__ import print_function from numpy import array, array_equal, allclose  myarr0 = array([1, 0]) myarr1 = array([3.4499999, 3.2]) mylistarr = [array([1, 2, 3]), array([1, 0]), array([3.45, 3.2])]  #test for identity: def is_arr_in_list(myarr, list_arrays):     return next((True for elem in list_arrays if elem is myarr), False)  print(is_arr_in_list(mylistarr[2], mylistarr)) #->True print(is_arr_in_list(myarr0, mylistarr)) #->False #myarr0 is equal to mylistarr[1], but it is not the same object!  #test for exact equality def arreq_in_list(myarr, list_arrays):     return next((True for elem in list_arrays if array_equal(elem, myarr)), False)  print(arreq_in_list(myarr0, mylistarr)) # -> True print(arreq_in_list(myarr1, mylistarr)) # -> False  #test for approximate equality (for floating point types) def arreqclose_in_list(myarr, list_arrays):     return next((True for elem in list_arrays if elem.size == myarr.size and allclose(elem, myarr)), False)  print(arreqclose_in_list(myarr1, mylistarr)) #-> True 

PS:do NOT use list for a variable name, as it is a reserved keyword, and often leads to subtle errors. Similarly, do not use array.

Answer 2

lets say you have an array like this:

a= [array([ 1, 24,  4, 5]), array([ 22,   4, 123]), array([11,  1,  1])] #convert all subarrays to list a= [ list(item) for item in a ] 

no you can check for a sublist like this:

In [80]: [1,22,4] in a Out[80]: False  In [81]: [1,24,4,5] in a Out[81]: True