Python: Numpy dtype U32 - simple if-else statement

Question

I dont understand the following behavior of a numpy array. Given the following array f:

array([u'1.8', u'1.8', u'2.4', u'2.2', u'2.0', u'2.1', u'2.8', u'3.2',
       u'3.3', u'3.4', u'2.8'], dtype='<U32')

for a in f:
    if a > 2.2:
        print "greater"
    else:
        print "smaller"

The result is always greater.

Any reason why your array contains ``strings`` instead of ``numbers``? — MSeifert, Feb 12 '16 at 16:24

score 4 · Answer 1 · edited Jan 03 '20 at 11:02

4

This is because the values in your array are Unicode strings, not integers. In python, a numeric type will always be "greater" than a non numeric type on comparison. See this SO answer for a more in depth explanation.

To get the functionality you intended you need to convert the strings to numbers.

edited Jan 03 '20 at 11:02

Md. Sabbir Ahmed

850
8
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answered Feb 12 '16 at 16:24

nathan.medz

1,595
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21

Python: Numpy dtype U32 - simple if-else statement

1 Answers1