## Fix Python – How do I create a numpy array of all True or all False?

In Python, how do I create a numpy array of arbitrary shape filled with all True or all False?
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## Fix Python – How do I calculate percentiles with python/numpy?

Is there a convenient way to calculate percentiles for a sequence or single-dimensional numpy array?
I am looking for something similar to Excel’s percentile function.
I looked in NumPy’s statistics reference, and couldn’t find this. All I could find is the median (50th percentile), but not something more specific.
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## Fix Python – Better way to shuffle two numpy arrays in unison

I have two numpy arrays of different shapes, but with the same length (leading dimension). I want to shuffle each of them, such that corresponding elements continue to correspond — i.e. shuffle them in unison with respect to their leading indices.
This code works, and illustrates my goals:
def shuffle_in_unison(a, b):
assert len(a) == len(b)
….

## Fix Python – Convert array of indices to one-hot encoded array in NumPy

Given a 1D array of indices:
a = array([1, 0, 3])

I want to one-hot encode this as a 2D array:
b = array([[0,1,0,0], [1,0,0,0], [0,0,0,1]])

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## Fix Python – What is the difference between ndarray and array in NumPy?

What is the difference between ndarray and array in NumPy? Where is their implementation in the NumPy source code?
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## Fix Python – Concatenating two one-dimensional NumPy arrays

How do I concatenate two one-dimensional arrays in NumPy? I tried numpy.concatenate:
import numpy as np
a = np.array([1, 2, 3])
b = np.array([4, 5])
np.concatenate(a, b)

But I get an error:

TypeError: only length-1 arrays can be converted to Python scalars

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## Fix Python – Convert NumPy array to Python list

How do I convert a NumPy array into a Python List?
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## Fix Python – How do I convert a PIL Image into a NumPy array?

How do I convert a PIL Image back and forth to a NumPy array so that I can do faster pixel-wise transformations than PIL’s PixelAccess allows? I can convert it to a NumPy array via:
pic = Image.open(“foo.jpg”)
pix = numpy.array(pic.getdata()).reshape(pic.size, pic.size, 3)

But how do I load it back into the PIL Image after I’ve modified the….

## Fix Python – What is the difference between flatten and ravel functions in numpy?

import numpy as np
y = np.array(((1,2,3),(4,5,6),(7,8,9)))
OUTPUT:
print(y.flatten())
[1 2 3 4 5 6 7 8 9]
print(y.ravel())
[1 2 3 4 5 6 7 8 9]

Both function return the same list.
Then what is the need of two different functions performing same job.
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## Fix Python – What is the purpose of meshgrid in Python / NumPy?

Can someone explain to me what is the purpose of meshgrid function in Numpy? I know it creates some kind of grid of coordinates for plotting, but I can’t really see the direct benefit of it.
I am studying “Python Machine Learning” from Sebastian Raschka, and he is using it for plotting the decision borders. See input 11 here.
I have also tried thi….