CODEWITHSUNDEEP
pythonnumpymasked-array
SBFRF
SBFRF

Reputation: 163

effectively check if data are masked array and all data are masked True

I have arrays that are simple numpy.ndarrays while other times the same variable may be a masked array. I'd like to figure out the most effective way to check if there are data in the array and that ALL are not masked

I've got the below to illustrate:

data0 = np.ma.array([3,3,3,3,3], mask=[True, True, False, True, True])
data1 = np.ma.array([3,3,3,3,3], mask=[True, True, True, True, True])
data2 = np.array([3,3,3,3,3])
for dataNum, data in enumerate([data0, data1, data2]):
    if (isinstance(data, np.ma.masked_array) and not data.mask.all()) or (isinstance(data,np.ndarray)):
         print('if statement passed data{}'.format(dataNum))

but this allows for all 3 to pass. I assume because a masked_array is considered an ndarray

if statement passed data0 if statement passed data1 if statement passed data2

i'd like for data0 and data2 to pass so I can operate on the data. Ideally it's something simple too :)

Upvotes: 0

Views: 554

Answers (3)

Jsl
Jsl

Reputation: 862

Here's a simple solution that avoids the multiple cases by first ensuring that the data is masked and then testing the mask (which defaults to False):

not np.ma.array(data).mask.all()

So for your specific example:

for dataNum, data in enumerate([data0, data1, data2]):
    if not np.ma.array(data).mask.all():
        print('if statement passed data{}'.format(dataNum))

gives the results you wanted.

Edit: for reduced overhead you can use copy=False:

not np.ma.array(data, copy=False).mask.all()

Upvotes: 2

rpanai
rpanai

Reputation: 13437

There are two problems:

  1. for all arrays you have isinstance(data,np.ndarray) to be True.
  2. not data.mask.all() looks a typo to me.

This should fix

for dataNum, data in enumerate([data0, data1, data2]):
    if ((isinstance(data, np.ma.masked_array) and  data.mask.all()) or 
        not (isinstance(data, np.ma.masked_array))):
         print('if statement passed data{}'.format(dataNum))

Upvotes: 0

SBFRF
SBFRF

Reputation: 163

turns out the np.ma.isMaskedArray solves this problem:

for dataNum, data in enumerate([data0, data1, data2]):
    if (np.ma.isMaskedArray(data) and not data.mask.all()) or not np.ma.isMaskedArray (data):
         print('if statement passed data{}'.format(dataNum))

if statement passed data0 if statement passed data2

Upvotes: 1

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