def nearest_neighbor_clusters(protein, gap_agreement_weight=0.):
"""Assign each extra MSA sequence to its nearest neighbor in sampled MSA."""
# Determine how much weight we assign to each agreement. In theory, we could
# use a full blosum matrix here, but right now let's just down-weight gap
# agreement because it could be spurious.
# Never put weight on agreeing on BERT mask
weights = tf.concat(
[tf.ones(21), gap_agreement_weight * tf.ones(1),
np.zeros(1)], 0)
# Make agreement score as weighted Hamming distance
sample_one_hot = (protein['msa_mask'][:, :, None] *
tf.one_hot(protein['msa'], 23))
extra_one_hot = (protein['extra_msa_mask'][:, :, None] *
tf.one_hot(protein['extra_msa'], 23))
num_seq, num_res, _ = shape_helpers.shape_list(sample_one_hot)
extra_num_seq, _, _ = shape_helpers.shape_list(extra_one_hot)
# Compute tf.einsum('mrc,nrc,c->mn', sample_one_hot, extra_one_hot, weights)
# in an optimized fashion to avoid possible memory or computation blowup.
agreement = tf.matmul(tf.reshape(extra_one_hot,
[extra_num_seq, num_res * 23]),
tf.reshape(sample_one_hot * weights,
[num_seq, num_res * 23]),
transpose_b=True)
# Assign each sequence in the extra sequences to the closest MSA sample
protein['extra_cluster_assignment'] = tf.argmax(agreement,
axis=1,
output_type=tf.int32)
return protein
def make_msa_mask(protein):
"""Mask features are all ones, but will later be zero-padded."""
protein['msa_mask'] = tf.ones(shape_helpers.shape_list(protein['msa']),
dtype=tf.float32)
protein['msa_row_mask'] = tf.ones(shape_helpers.shape_list(
protein['msa'])[0],
dtype=tf.float32)
return protein
def make_masked_msa(protein, config, replace_fraction):
"""Create data for BERT on raw MSA."""
# Add a random amino acid uniformly
random_aa = tf.constant([0.05] * 20 + [0., 0.], dtype=tf.float32)
categorical_probs = (config.uniform_prob * random_aa +
config.profile_prob * protein['hhblits_profile'] +
config.same_prob * tf.one_hot(protein['msa'], 22))
# Put all remaining probability on [MASK] which is a new column
pad_shapes = [[0, 0] for _ in range(len(categorical_probs.shape))]
pad_shapes[-1][1] = 1
mask_prob = 1. - config.profile_prob - config.same_prob - config.uniform_prob
assert mask_prob >= 0.
categorical_probs = tf.pad(categorical_probs,
pad_shapes,
constant_values=mask_prob)
sh = shape_helpers.shape_list(protein['msa'])
mask_position = tf.random.uniform(sh) < replace_fraction
bert_msa = shaped_categorical(categorical_probs)
bert_msa = tf.where(mask_position, bert_msa, protein['msa'])
# Mix real and masked MSA
protein['bert_mask'] = tf.cast(mask_position, tf.float32)
protein['true_msa'] = protein['msa']
protein['msa'] = bert_msa
return protein
def shaped_categorical(probs, epsilon=1e-10):
ds = shape_helpers.shape_list(probs)
num_classes = ds[-1]
counts = tf.random.categorical(tf.reshape(tf.log(probs + epsilon),
[-1, num_classes]),
1,
dtype=tf.int32)
return tf.reshape(counts, ds[:-1])
def randomly_replace_msa_with_unknown(protein, replace_proportion):
"""Replace a proportion of the MSA with 'X'."""
msa_mask = (tf.random.uniform(shape_helpers.shape_list(protein['msa'])) <
replace_proportion)
x_idx = 20
gap_idx = 21
msa_mask = tf.logical_and(msa_mask, protein['msa'] != gap_idx)
protein['msa'] = tf.where(msa_mask,
tf.ones_like(protein['msa']) * x_idx,
protein['msa'])
aatype_mask = (tf.random.uniform(
shape_helpers.shape_list(protein['aatype'])) < replace_proportion)
protein['aatype'] = tf.where(aatype_mask,
tf.ones_like(protein['aatype']) * x_idx,
protein['aatype'])
return protein
def test_shape_list(self):
"""Test that shape_list can allow for reshaping to dynamic shapes."""
a = tf.zeros([10, 4, 4, 2])
p = tf.placeholder(tf.float32, shape=[None, None, 1, 4, 4])
shape_dyn = shape_helpers.shape_list(p)[:2] + [4, 4]
b = tf.reshape(a, shape_dyn)
with self.session() as sess:
out = sess.run(b, feed_dict={p: np.ones((20, 1, 1, 4, 4))})
self.assertAllEqual(out.shape, (20, 1, 4, 4))
def squeeze_features(protein):
"""Remove singleton and repeated dimensions in protein features."""
protein['aatype'] = tf.argmax(protein['aatype'],
axis=-1,
output_type=tf.int32)
for k in [
'domain_name', 'msa', 'num_alignments', 'seq_length', 'sequence',
'superfamily', 'deletion_matrix', 'resolution',
'between_segment_residues', 'residue_index',
'template_all_atom_masks'
]:
if k in protein:
final_dim = shape_helpers.shape_list(protein[k])[-1]
if isinstance(final_dim, int) and final_dim == 1:
protein[k] = tf.squeeze(protein[k], axis=-1)
for k in ['seq_length', 'num_alignments']:
if k in protein:
protein[k] = protein[k][0] # Remove fake sequence dimension
return protein
def block_delete_msa(protein, config):
"""Sample MSA by deleting contiguous blocks.
Jumper et al. (2021) Suppl. Alg. 1 "MSABlockDeletion"
Arguments:
protein: batch dict containing the msa
config: ConfigDict with parameters
Returns:
updated protein
"""
num_seq = shape_helpers.shape_list(protein['msa'])[0]
block_num_seq = tf.cast(
tf.floor(tf.cast(num_seq, tf.float32) * config.msa_fraction_per_block),
tf.int32)
if config.randomize_num_blocks:
nb = tf.random.uniform([], 0, config.num_blocks + 1, dtype=tf.int32)
else:
nb = config.num_blocks
del_block_starts = tf.random.uniform([nb], 0, num_seq, dtype=tf.int32)
del_blocks = del_block_starts[:, None] + tf.range(block_num_seq)
del_blocks = tf.clip_by_value(del_blocks, 0, num_seq - 1)
del_indices = tf.unique(tf.sort(tf.reshape(del_blocks, [-1])))[0]
# Make sure we keep the original sequence
sparse_diff = tf.sets.difference(
tf.range(1, num_seq)[None], del_indices[None])
keep_indices = tf.squeeze(tf.sparse.to_dense(sparse_diff), 0)
keep_indices = tf.concat([[0], keep_indices], axis=0)
for k in _MSA_FEATURE_NAMES:
if k in protein:
protein[k] = tf.gather(protein[k], keep_indices)
return protein
def summarize_clusters(protein):
"""Produce profile and deletion_matrix_mean within each cluster."""
num_seq = shape_helpers.shape_list(protein['msa'])[0]
def csum(x):
return tf.math.unsorted_segment_sum(
x, protein['extra_cluster_assignment'], num_seq)
mask = protein['extra_msa_mask']
mask_counts = 1e-6 + protein['msa_mask'] + csum(mask) # Include center
msa_sum = csum(mask[:, :, None] * tf.one_hot(protein['extra_msa'], 23))
msa_sum += tf.one_hot(protein['msa'], 23) # Original sequence
protein['cluster_profile'] = msa_sum / mask_counts[:, :, None]
del msa_sum
del_sum = csum(mask * protein['extra_deletion_matrix'])
del_sum += protein['deletion_matrix'] # Original sequence
protein['cluster_deletion_mean'] = del_sum / mask_counts
del del_sum
return protein
def make_template_mask(protein):
protein['template_mask'] = tf.ones(shape_helpers.shape_list(
protein['template_domain_names']),
dtype=tf.float32)
return protein
def random_crop_to_size(protein,
crop_size,
max_templates,
shape_schema,
subsample_templates=False):
"""Crop randomly to `crop_size`, or keep as is if shorter than that."""
seq_length = protein['seq_length']
if 'template_mask' in protein:
num_templates = tf.cast(
shape_helpers.shape_list(protein['template_mask'])[0], tf.int32)
else:
num_templates = tf.constant(0, dtype=tf.int32)
num_res_crop_size = tf.math.minimum(seq_length, crop_size)
# Ensures that the cropping of residues and templates happens in the same way
# across ensembling iterations.
# Do not use for randomness that should vary in ensembling.
seed_maker = utils.SeedMaker(
initial_seed=protein['random_crop_to_size_seed'])
if subsample_templates:
templates_crop_start = tf.random.stateless_uniform(
shape=(),
minval=0,
maxval=num_templates + 1,
dtype=tf.int32,
seed=seed_maker())
else:
templates_crop_start = 0
num_templates_crop_size = tf.math.minimum(
num_templates - templates_crop_start, max_templates)
num_res_crop_start = tf.random.stateless_uniform(shape=(),
minval=0,
maxval=seq_length -
num_res_crop_size + 1,
dtype=tf.int32,
seed=seed_maker())
templates_select_indices = tf.argsort(
tf.random.stateless_uniform([num_templates], seed=seed_maker()))
for k, v in protein.items():
if k not in shape_schema or ('template' not in k
and NUM_RES not in shape_schema[k]):
continue
# randomly permute the templates before cropping them.
if k.startswith('template') and subsample_templates:
v = tf.gather(v, templates_select_indices)
crop_sizes = []
crop_starts = []
for i, (dim_size, dim) in enumerate(
zip(shape_schema[k], shape_helpers.shape_list(v))):
is_num_res = (dim_size == NUM_RES)
if i == 0 and k.startswith('template'):
crop_size = num_templates_crop_size
crop_start = templates_crop_start
else:
crop_start = num_res_crop_start if is_num_res else 0
crop_size = (num_res_crop_size if is_num_res else
(-1 if dim is None else dim))
crop_sizes.append(crop_size)
crop_starts.append(crop_start)
protein[k] = tf.slice(v, crop_starts, crop_sizes)
protein['seq_length'] = num_res_crop_size
return protein
def make_seq_mask(protein):
protein['seq_mask'] = tf.ones(shape_helpers.shape_list(protein['aatype']),
dtype=tf.float32)
return protein
