In pygame, I have a surface:
im = pygame.image.load('foo.png').convert_alpha()
im = pygame.transform.scale(im, (64, 64))
How can I get a grayscale copy of the image, or convert the image data to grayscale? I have numpy.
Use a Surfarray, and filter it with numpy or Numeric:
def grayscale(self, img):
arr = pygame.surfarray.array3d(img)
#luminosity filter
avgs = [[(r*0.298 + g*0.587 + b*0.114) for (r,g,b) in col] for col in arr]
arr = numpy.array([[[avg,avg,avg] for avg in col] for col in avgs])
return pygame.surfarray.make_surface(arr)
After a lot of research, I came up with this solution, because answers to this question were too slow for what I wanted this feature to:
def greyscale(surface: pygame.Surface):
start = time.time() # delete me!
arr = pygame.surfarray.array3d(surface)
# calulates the avg of the "rgb" values, this reduces the dim by 1
mean_arr = np.mean(arr, axis=2)
# restores the dimension from 2 to 3
mean_arr3d = mean_arr[..., np.newaxis]
# repeat the avg value obtained before over the axis 2
new_arr = np.repeat(mean_arr3d[:, :, :], 3, axis=2)
diff = time.time() - start # delete me!
# return the new surface
return pygame.surfarray.make_surface(new_arr)
I used time.time() to calculate the time cost for this approach, so for a (800, 600, 3) array it takes: 0.026769161224365234 s to run.
As you pointed out, here is a variant preserving the luminiscence:
def greyscale(surface: pygame.Surface):
arr = pygame.surfarray.pixels3d(surface)
mean_arr = np.dot(arr[:,:,:], [0.216, 0.587, 0.144])
mean_arr3d = mean_arr[..., np.newaxis]
new_arr = np.repeat(mean_arr3d[:, :, :], 3, axis=2)
return pygame.surfarray.make_surface(new_arr)
The easiest way is to iterate over all the pixels in your image and call .get_at(...) and .set_at(...).
This will be pretty slow, so in answer to your implicit suggestion about using NumPy, look at http://www.pygame.org/docs/tut/surfarray/SurfarrayIntro.html. The concepts and most of the code are identical.
Related
I'm trying to have a layer in keras that takes a flat tensor x (doesn't have zero value in it and shape = (batch_size, units)) multiplied by a mask (of the same shape), and it will sort it in the way that masked values will be placed first in the output (the order of the elements value doesn't matter). For clarity here is an example (batch_size = 1, units = 8):
It seems simple but the problem is that I can't find a good solution. Any code or idea is appreciated.
My current code is as below, If you know a more efficient way please let me know.
class Sort(keras.layers.Layer):
def call(self, inputs):
x = inputs.numpy()
nonx, nony = x.nonzero() # idxs of nonzero elements
zero = [np.where(x == 0)[0][0], np.where(x == 0)[1][0]] # idx of first zero
x_shape = tf.shape(inputs)
result = np.zeros((x_shape[0], x_shape[1], 2), dtype = 'int') # mapping matrix
result[:, :, 0] += zero[0]
result[:, :, 1] += zero[1]
p = np.zeros((x_shape[0]), dtype = 'int')
for i, j in zip(nonx, nony):
result[i, p[i]] = [i, j]
p[i] += 1
y = tf.gather_nd(inputs, result)
return y
I want to concatenate two tensors checkerboard-ly in tensorflow2, like examples showed below:
example 1:
a = [[1,1],[1,1]]
b = [[0,0],[0,0]]
concated_a_and_b = [[1,0,1,0],[0,1,0,1]]
example 2:
a = [[1,1,1],[1,1,1],[1,1,1]]
b = [[0,0,0],[0,0,0],[0,0,0]]
concated_a_and_b = [[1,0,1,0,1,0],[0,1,0,1,0,1],[1,0,1,0,1,0]]
Is there a decent way in tensorflow2 to concatenate them like this?
A bit of background for this:
I first split a tensor c with a checkerboard mask into two halves a and b. A after some transformation I have to concat them back into oringnal shape and order.
What I mean by checkerboard-ly:
Step 1: Generate a matrix with alternated values
You can do this by first concatenating into [1, 0] pairs, and then by applying a final reshape.
Step 2: Reverse some rows
I split the matrix into two parts, reverse the second part and then rebuild the full matrix by picking alternatively from the first and second part
Code sample:
import math
import numpy as np
import tensorflow as tf
a = tf.ones(shape=(3, 4))
b = tf.zeros(shape=(3, 4))
x = tf.expand_dims(a, axis=-1)
y = tf.expand_dims(b, axis=-1)
paired_ones_zeros = tf.concat([x, y], axis=-1)
alternated_values = tf.reshape(paired_ones_zeros, [-1, a.shape[1] + b.shape[1]])
num_samples = alternated_values.shape[0]
middle = math.ceil(num_samples / 2)
is_num_samples_odd = middle * 2 != num_samples
# Gather first part of the matrix, don't do anything to it
first_elements = tf.gather_nd(alternated_values, [[index] for index in range(middle)])
# Gather second part of the matrix and reverse its elements
second_elements = tf.reverse(tf.gather_nd(alternated_values, [[index] for index in range(middle, num_samples)]), axis=[1])
# Pick alternatively between first and second part of the matrix
indices = np.concatenate([[[index], [index + middle]] for index in range(middle)], axis=0)
if is_num_samples_odd:
indices = indices[:-1]
output = tf.gather_nd(
tf.concat([first_elements, second_elements], axis=0),
indices
)
print(output)
I know this is not a decent way as it will affect time and space complexity. But it solves the above problem
def concat(tf1, tf2):
result = []
for (index, (tf_item1, tf_item2)) in enumerate(zip(tf1, tf2)):
item = []
for (subitem1, subitem2) in zip(tf_item1, tf_item2):
if index % 2 == 0:
item.append(subitem1)
item.append(subitem2)
else:
item.append(subitem2)
item.append(subitem1)
concated_a_and_b.append(item)
return concated_a_and_b
I'm going to write a BasicLSTMCell with C++,and I need check it work well.
I used tf.nn.rnn_cell.BasicLSTMCell to implement a LSTM with 4 cells,and I set
forget_bias to 1.Then I Check the LSTM'bias using this code:
//////////////////////////////////////////////////////////////
with tf.variable_scope("LSTM"):
Cell=tf.nn.rnn_cell.BasicLSTMCell(4,forget_bias=1,state_is_tuple=True)
Sessin=tf.Session()
state=Cell.zero_state(1,dtype=tf.float32)
with tf.variable_scope("Ut_def"):
out,D=tf.nn.dynamic_rnn(
cell=Cell,inputs=Feed,
initial_state=state,
time_major=False)
Sessin.run(tf.global_variables_initializer())
#Saver.save(Sessin,"./123/Var",global_step=1)
out,D=Sessin.run([out,D],feed_dict={Feed:np.arange(8).reshape(1,2,4)})
tf.train.Saver().save(Sessin,"./123/Var",global_step=1)
trainable_vars_dict = {}
for key in tf.get_collection(tf.GraphKeys.TRAINABLE_VARIABLES):
trainable_vars_dict[key.name] = Sessin.run(key)
# Checking the names of the keys
print(key.name)
lstm_weight_vals = trainable_vars_dict["Ut_def/RNN/BasicLSTMCell/Linear/Matrix:0"]
B=trainable_vars_dict["Ut_def/RNN/BasicLSTMCell/Linear/Bias:0"]
print(B)
/////////////////////////////////////////////////////////////
But I found these bias were all zeros whatever I changed the forget_bias.
Someone know that what it is going on?
For figuring out how lstm work,I just using wights and bias extracting from tensorflow for getting same result. Absolutely they are not equivalent.
w_i, w_C, w_f, w_o = np.split(lstm_weight_vals, 4, axis=1)
w_xi = w_i[:4, :]
w_hi = w_i[4:, :]
w_xC = w_C[:4, :]
w_hC = w_C[4:, :]
w_xf = w_f[:4, :]
w_hf = w_f[4:, :]
w_xo = w_o[4:, :]
w_ho = w_o[4:, :]
Input=tf.range(4,dtype=tf.float32)
Input=tf.reshape(Input,shape=[1,4])
i=tf.sigmoid(tf.matmul(tf.zeros(shape=[1,4]),w_xi)+tf.matmul(Input,w_hi))
o=tf.sigmoid(tf.matmul(tf.zeros(shape=[1,4]),w_xo)+tf.matmul(Input,w_ho))
g=tf.tanh(tf.matmul(tf.zeros(shape=[1,4]),w_xC)+tf.matmul(Input,w_hC))
f=tf.sigmoid(tf.matmul(tf.zeros(shape=[1,4]),w_xf)+tf.matmul(Input,w_hf))
Cstate=tf.zeros(shape=[1,4])*f+i*g
Hstate=tf.tanh(Cstate)*o
Input=Input+4
i=tf.sigmoid(tf.matmul(Cstate,w_xi)+tf.matmul(Input,w_hi))
o=tf.sigmoid(tf.matmul(Cstate,w_xo)+tf.matmul(Input,w_ho))
g=tf.tanh(tf.matmul(Cstate,w_xC)+tf.matmul(Input,w_hC))
f=tf.sigmoid(tf.matmul(Cstate,w_xf)+tf.matmul(Input,w_hf))
Cstate=Cstate*f+i*g
Hstate=tf.tanh(Cstate)*o
I has found wrong code. Code should like this:
i=tf.sigmoid(tf.matmul(Hstate,w_xi)+tf.matmul(Input,w_hi))
o=tf.sigmoid(tf.matmul(Hstate,w_xo)+tf.matmul(Input,w_ho))
g=tf.tanh(tf.matmul(Hstate,w_xC)+tf.matmul(Input,w_hC))
f=tf.sigmoid(tf.matmul(Hstate,w_xf)+tf.matmul(Input,w_hf)+1)
It's Hstate instead of Csatae.
Given a 2-dimensional tensor t, what's the fastest way to compute a tensor h where
h[i, :] = tf.histogram_fixed_width(t[i, :], vals, nbins)
I.e. where tf.histogram_fixed_width is called per row of the input tensor t?
It seems that tf.histogram_fixed_width is missing an axis parameter that works like, e.g., tf.reduce_sum's axis parameter.
tf.histogram_fixed_width works on the entire tensor indeed. You have to loop through the rows explicitly to compute the per-row histograms. Here is a complete working example using TensorFlow's tf.while_loop construct :
import tensorflow as tf
t = tf.random_uniform([2, 2])
i = 0
hist = tf.constant(0, shape=[0, 5], dtype=tf.int32)
def loop_body(i, hist):
h = tf.histogram_fixed_width(t[i, :], [0.0, 1.0], nbins=5)
return i+1, tf.concat_v2([hist, tf.expand_dims(h, 0)], axis=0)
i, hist = tf.while_loop(
lambda i, _: i < 2, loop_body, [i, hist],
shape_invariants=[tf.TensorShape([]), tf.TensorShape([None, 5])])
sess = tf.InteractiveSession()
print(hist.eval())
Inspired by keveman's answer and because the number of rows of t is fixed and rather small, I chose to use a combination of tf.gather to split rows and tf.pack to join rows. It looks simple and works, will see if it is efficient...
t_histo_rows = [
tf.histogram_fixed_width(
tf.gather(t, [row]),
vals, nbins)
for row in range(t_num_rows)]
t_histo = tf.pack(t_histo_rows, axis=0)
I would like to propose another implementation.
This implementation can also handle multi axes and unknown dimensions (batching).
def histogram(tensor, nbins=10, axis=None):
value_range = [tf.reduce_min(tensor), tf.reduce_max(tensor)]
if axis is None:
return tf.histogram_fixed_width(tensor, value_range, nbins=nbins)
else:
if not hasattr(axis, "__len__"):
axis = [axis]
other_axis = [x for x in range(0, len(tensor.shape)) if x not in axis]
swap = tf.transpose(tensor, [*other_axis, *axis])
flat = tf.reshape(swap, [-1, *np.take(tensor.shape.as_list(), axis)])
count = tf.map_fn(lambda x: tf.histogram_fixed_width(x, value_range, nbins=nbins), flat, dtype=(tf.int32))
return tf.reshape(count, [*np.take([-1 if a is None else a for a in tensor.shape.as_list()], other_axis), nbins])
The only slow part here is tf.map_fn but it is still faster than the other solutions mentioned.
If someone knows a even faster implementation please comment since this operation is still very expensive.
answers above is still slow running in GPU. Here i give an another option, which is faster(at least in my running envirment), but it is limited to 0~1 (you can normalize the value first). the train_equal_mask_nbin can be defined once in advance
def histogram_v3_nomask(tensor, nbins, row_num, col_num):
#init mask
equal_mask_list = []
for i in range(nbins):
equal_mask_list.append(tf.ones([row_num, col_num], dtype=tf.int32) * i)
#[nbins, row, col]
#[0, row, col] is tensor of shape [row, col] with all value 0
#[1, row, col] is tensor of shape [row, col] with all value 1
#....
train_equal_mask_nbin = tf.stack(equal_mask_list, axis=0)
#[inst, doc_len] float to int(equaly seg float in bins)
int_input = tf.cast(tensor * (nbins), dtype=tf.int32)
#input [row,col] -> copy N times, [nbins, row_num, col_num]
int_input_nbin_copy = tf.reshape(tf.tile(int_input, [nbins, 1]), [nbins, row_num, col_num])
#calculate histogram
histogram = tf.transpose(tf.count_nonzero(tf.equal(train_equal_mask_nbin, int_input_nbin_copy), axis=2))
return histogram
With the advent of tf.math.bincount, I believe the problem has become much simpler.
Something like this should work:
def hist_fixed_width(x,st,en,nbins):
x=(x-st)/(en-st)
x=tf.cast(x*nbins,dtype=tf.int32)
x=tf.clip_by_value(x,0,nbins-1)
return tf.math.bincount(x,minlength=nbins,axis=-1)
Here is how my code looks like:
N = 16, num_ckfs = 5
init_variances = tf.placeholder(tf.float64, shape=[ num_ckfs, N],name='inital_variances')
init_states = tf.placeholder(tf.float64, shape=[num_ckfs, N], name='init_states')
#some more code
predicted_state = prior_state_expanded + kalman_gain * diff_expanded
error_covariance = sum_cov_cholesky + tf.batch_matmul(kg , kalman_gain, adj_x=True)
projected_output = tf.batch_matmul(predicted_state,input_vectors_extra, adj_y=True)
session = tf.Session()
init_var = [10 for i in range(N)]
init_var_ckfs = [init_var for i in range(num_ckfs)]
init_state = [0 for i in range(N)]
init_state_ckfs = [init_state for i in range(num_ckfs)]
for timestep in range(10):
out= session.run([projected_output, predicted_state, error_covariance], {init_variances:init_var_ckfs, init_states:init_state_ckfs })
#for the next tilmestep, I want to initialize init_state_ckfs with the predicted_state, and the init_var_ckfs with error_covariance.
#predicted_state is a tensor with shape (num_ckfs, 1, N)
#error_covariance is a tensor with shape (num_ckfs, N, N): I just need the diagonal elements from each of the N X N matrices
Although I have mentioned this in the code as a comment, I will mention it here again. I am wanting to know how to use the updated tensors from the previous time step by converting them into lists and feeding them as inputs for the next time step. Can someone please help me.
use tf.assign to assign to the placeholder the last value of the variable. As long as the Session is active the state is preserved