Number of values within a certain range in Python-CodePudding

I have an array A. I want to print total number of values in the range [1e-11,1e-7]. But I am getting an error. I present the expected output.

import numpy as np 

A=np.array([ 4.21922009e 002,  4.02356746e 002,  3.96553289e-09,
        3.91811967e-010,  3.88467908e-08,  3.86636300e-010])

B=1e-11<A<1e-07
print(B)

The error is

 in <module>
    B=1e-11<A<1e-07

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

The expected output is

CodePudding user response：

You can't use your code with numpy array:

B = sum((1e-11<A) & (A<1e-07))
print(B)

# Output
4

It doesn't make sense for Python (and not numpy) to compare 2 scalar values to an array.

CodePudding user response：

The numpy-way is to refactor the interval condition into two subconditions using the & operator:

a = np.array([ 4.21922009e 002,  4.02356746e 002,  3.96553289e-09,
        3.91811967e-010,  3.88467908e-08,  3.86636300e-010])

mask = (1e-11<a) & (a<1e-07)

# if you care about the values of the filtered array
print(a[mask].size)

# or just
print(np.count_nonzero(mask))