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# Utility functions for managing 3x3 matrices for cv2.warpAffine in pure numpy

import numpy as np


def identity():
    return np.eye(3, dtype=np.float64)


def affine(A=None, t=None):

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# Reimplementation of: https://github.com/aladdinpersson/Machine-Learning-Collection/blob/master/ML/Pytorch/object_detection/metrics/mean_avg_precision.py
# Now with more vectorisation!

def precision_recall_curve_th(is_tp, confs, n_true, eps=1e-8):
    # Sort by confs
    order = (-confs).argsort()
    is_tp = is_tp[order]
    confs = confs[order]

    # Cumulative sum true positives and number of predictions

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# BIG NOTE: 
# I made this becuase I thought the method was interesting. It's not useful in it's current form. 
# If you can, use an index instead. https://stackoverflow.com/a/27895337

from sqlalchemy import Column, Integer, Float, ForeignKey, event, DDL
from sqlalchemy.schema import CreateSchema
from sqlalchemy.dialects.postgresql import DOUBLE_PRECISION
from sqlalchemy.ext.declarative import declarative_base, declared_attr

Base = declarative_base()

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import collections

class ListLike(collections.abc.MutableSequence):
    '''
    A list-like interface wrapping dictionary-like objects.

    Uses integer keys, like you would for a list, has range checking,
    negative indexing and slicing working as you'd expect.
    i.e.
        with shelve.open('foo.dat') as sf:

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import bisect
import numpy as np
import collections.abc

class TwoLevelIndex(collections.abc.Sequence):
    def __init__(self, coll):
        counts = [len(thing) for thing in coll]
        self.cum_counts = np.cumsum(counts)
    def __getitem__(self, idx):
        seg_idx = bisect.bisect(self.cum_counts, idx)

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# I keep properties on my main nn.Modules. e.g. a list of the training statistics the model is tracking.
# I wanted to perform a set of extra actions across multiple different modules without having to
#  - write those steps into each of the 5+ different model definitions, or
#  - explicitly expose those values on the wrapper module.
# It's fairly trivial, but if you don't use the try: super(), it doesn't keep the `wrapped` property.

import torch
import torch.nn as nn

class Wrapper(nn.Module):

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def derive(_from, _coll='_derived', name=None):
    '''
    Creates a decorator that caches derived values.
    Utilises a property on the object to keep a collection of derived properties,
    but requires the calling obj to manage that collection (clearing, instantiation, etc).

    Args:
        _from (str): Property this property is derived from
        _coll (str, optional): Collection name of derived property names
        name (str, optional): Overwrite the property used to cache

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from PIL import Image


# Assumes tensor is shaped [c, h, w]
Image.fromarray(tensor.detach().cpu().numpy().transpose([1, 2, 0])).save('test.png')

# Assumes tensor is shaped [n, c, h, w]
Image.fromarray(tensor[0].detach().cpu().numpy().transpose([1, 2, 0])).save('test.png')

# Yeah, pretty simple, but annoying to remember... 

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# Super simple 1D smoothing with just numpy. Just smooths a few sharp edges.

import math
import numpy as np

def gaussian_kernel(n=5):
  x = np.arange(n)/n
  g = math.e ** -(x**2/((n - 2)**2)) # drop the constant factor at the start
  return g/g.sum() # normalise so it sums to 1

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# Simplest case (note: VideoDataset.__get__ puts frames on CPU)
import nvvl
d = nvvl.VideoDataset(['prepared.mp4'], 3)
fr = d[0]
print(type(fr))
print(fr.shape)

# Custom processing (note: VideoDataset.__get__ puts frames on CPU)
import nvvl
d = nvvl.VideoDataset(['prepared.mp4'], 3, processing={'a': nvvl.ProcessDesc()})