ValueError: unpack: when trying to split fashion_mnist into 3 splits - keras

(train_dataset,validation_dataset,test_dataset) = tfds.load('fashion_mnist',
with_info=True, as_supervised=True,
split=['train[:80%]', 'train[80%:90%]', 'train[90%:]'])
I am trying to split the fashion_mnist into 3 sets-train test and validation. I'm not sure what the error is here as i am simply not able to resolve it.

The "fashion_mnist" dataset only has a train and a test split in Tensorflow Datasets (see documentation, Splits section), so in the split paramter it expects a list that has length at most 2, however you are using a list of length 3. In order to get a train, validation and test split, you could do the following:
whole_ds,info_ds = tfds.load("fashion_mnist", with_info = True, split='train+test', as_supervised=True)
n = tf.data.experimental.cardinality(whole_ds).numpy() # 70 000
train_num = int(n*0.8)
val_num = int(n*0.1)
train_ds = whole_ds.take(train_num)
val_ds = whole_ds.skip(train_num).take(val_num)
test_ds = whole_ds.skip(train_num+val_num)

If you want to retain the provided test data as your test data:
(train_data, validation_data, test_data),info = tfds.load(
name="fashion_mnist",
split=['train[:80%]', 'train[80%:]', 'test'],
as_supervised=True,
with_info=True)

Related

Huggingface Transformers NER - Offset Mapping Causing ValueError in NumPy boolean array indexing assignment

I was trying out the NER tutorial Token Classification with W-NUT Emerging Entities (https://huggingface.co/transformers/custom_datasets.html#tok-ner) in google colab using the Annotated Corpus for Named Entity Recognition data on Kaggle (https://www.kaggle.com/abhinavwalia95/entity-annotated-corpus?select=ner_dataset.csv).
I will outline my process in detail to facilitate an understanding of what I was doing and to let the community help me figure out the source of the indexing assignment error.
To load the data from google drive where I have saved it, I used the following code
# import pandas library
import pandas as pd
# columns to select
cols_to_select = ["Sentence #", "Word", "Tag"]
# google drive data path
data_path = '/content/drive/MyDrive/Colab Notebooks/ner/ner_dataset.csv'
# load the data from google colab
dataset = pd.read_csv(data_path, encoding="latin-1")[cols_to_select].fillna(method = 'ffill')
I run the following code to parse the sentences and tags
class SentenceGetter(object):
def __init__(self, data):
self.n_sent = 1
self.data = data
self.empty = False
agg_func = lambda s: [(w, t) for w, t in zip(s["Word"].values.tolist(),
s["Tag"].values.tolist())]
self.grouped = self.data.groupby("Sentence #").apply(agg_func)
self.sentences = [s for s in self.grouped]
def retrieve(self):
try:
s = self.grouped["Sentence: {}".format(self.n_sent)]
self.n_sent += 1
return s
except:
return None
# get full data
getter = SentenceGetter(dataset)
# get sentences
sentences = [[s[0] for s in sent] for sent in getter.sentences]
# get tags/labels
tags = [[s[1] for s in sent] for sent in getter.sentences]
# take a look at the data
print(sentences[0][0:5], tags[0][0:5], sep='\n')
I then split the data into train, val, and test sets
# import the sklearn module
from sklearn.model_selection import train_test_split
# split data in to temp and test sets
temp_texts, test_texts, temp_tags, test_tags = train_test_split(sentences,
tags,
test_size=0.20,
random_state=15)
# split data into train and validation sets
train_texts, val_texts, train_tags, val_tags = train_test_split(temp_texts,
temp_tags,
test_size=0.20,
random_state=15)
After splitting the data, I created encodings for tags and the tokens
unique_tags=dataset.Tag.unique()
# create tags to id
tag2id = {tag: id for id, tag in enumerate(unique_tags)}
# create id to tags
id2tag = {id: tag for tag, id in tag2id.items()}
I then installed the transformer library in colab
# install the transformers library
! pip install transformers
Next I imported the small bert model
# import the transformers module
from transformers import BertTokenizerFast
# import the small bert model
model_name = "google/bert_uncased_L-4_H-512_A-8"
tokenizer = BertTokenizerFast.from_pretrained(model_name)
I then created the encodings for the tokens
# create train set encodings
train_encodings = tokenizer(train_texts,
is_split_into_words=True,
return_offsets_mapping=True,
padding=True,
max_length=128,
truncation=True)
# create validation set encodings
val_encodings = tokenizer(val_texts,
is_split_into_words=True,
return_offsets_mapping=True,
padding=True,
max_length=128,
truncation=True)
# create test set encodings
test_encodings = tokenizer(test_texts,
is_split_into_words=True,
return_offsets_mapping=True,
padding=True,
max_length=128,
truncation=True)
In the tutorial, it uses offset-mapping to handle the problem that arise with word-piece tokenization, specifically, the mismatch between tokens and labels. It is when running the offset-mapping code in the tutorial that I get the error. Below is the offset mapping function used in the tutorial:
# the offset function
import numpy as np
def encode_tags(tags, encodings):
labels = [[tag2id[tag] for tag in doc] for doc in tags]
encoded_labels = []
for doc_labels, doc_offset in zip(labels, encodings.offset_mapping):
# create an empty array of -100
doc_enc_labels = np.ones(len(doc_offset),dtype=int) * -100
arr_offset = np.array(doc_offset)
# set labels whose first offset position is 0 and the second is not 0
doc_enc_labels[(arr_offset[:,0] == 0) & (arr_offset[:,1] != 0)] = doc_labels
encoded_labels.append(doc_enc_labels.tolist())
return encoded_labels
# return the encoded labels
train_labels = encode_tags(train_tags, train_encodings)
val_labels = encode_tags(val_tags, val_encodings)
test_labels = encode_tags(test_tags, test_encodings)
After running the above code, it gives me the following error, and I can't figure out where the source of the error lies. Any help and pointers would be appreciated.
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-19-afdff0186eb3> in <module>()
17
18 # return the encoded labels
---> 19 train_labels = encode_tags(train_tags, train_encodings)
20 val_labels = encode_tags(val_tags, val_encodings)
21 test_labels = encode_tags(test_tags, test_encodings)
<ipython-input-19-afdff0186eb3> in encode_tags(tags, encodings)
11
12 # set labels whose first offset position is 0 and the second is not 0
---> 13 doc_enc_labels[(arr_offset[:,0] == 0) & (arr_offset[:,1] != 0)] = doc_labels
14 encoded_labels.append(doc_enc_labels.tolist())
15
ValueError: NumPy boolean array indexing assignment cannot assign 38 input values to the 37 output values where the mask is true

ValueError: Number of features of the model must match the input. Model n_features is 464 and input n_features is 2

I am tryin to predict the cost of perfumes but I got error in the line "answer = (clf.predict(result))"
cursor.execute('SELECT * FROM info')
info = cursor.fetchall()
for line in info:
z.append(line[0:2])
y.append(line[2])
enc.fit(z)
x = enc.transform(z).toarray()
result = []
clf = tree.DecisionTreeClassifier()
clf = clf.fit(x, y)
new = input('enter the Model, Volume of your perfume to see the cost: example = Midnighto,50 ').split(',')
enc.fit([new])
result = enc.transform([new]).toarray()
answer = (clf.predict(result))
print(answer)
You don't have to fit enc again with your new input, only transform with the function fitted with X (what you do is OneHotEncoding the new sample taking in consideration only one possible value of the feature, you have to consider all the possible categories of the feature you have in your X data). So delete the next row:
enc.fit([new])
After that, please check if X and results has the same number of features. You can use function shape.
Furthermore, I recommend you use training and test data to see if your model is overfitted or not. Then, you can apply your personal predict.

How to get a specific sample from pytorch DataLoader?

In Pytorch, is there any way of loading a specific single sample using the torch.utils.data.DataLoader class? I'd like to do some testing with it.
The tutorial uses
trainloader = torch.utils.data.DataLoader(...)
images, labels = next(iter(trainloader))
to fetch a random batch of samples. Is there are way, using DataLoader, to get a specific sample?
Cheers
Turn off the shuffle in DataLoader
Use batch_size to calculate the batch in which the desired sample you are looking for falls in
Iterate to the desired batch
Code
import torch
import numpy as np
import itertools
X= np.arange(100)
batch_size = 2
dataloader = torch.utils.data.DataLoader(X, batch_size=batch_size, shuffle=False)
sample_at = 5
k = int(np.floor(sample_at/batch_size))
my_sample = next(itertools.islice(dataloader, k, None))
print (my_sample)
Output:
tensor([4, 5])
if you want to get a specific signle sample from your dataset you can
you should check Subset class.(https://pytorch.org/docs/stable/data.html#torch.utils.data.Subset)
something like this:
indices = [0,1,2] # select your indices here as a list
subset = torch.utils.data.Subset(train_set, indices)
trainloader = DataLoader(subset , batch_size = 16 , shuffle =False) #set shuffle to False
for image , label in trainloader:
print(image.size() , '\t' , label.size())
print(image[0], '\t' , label[0]) # index the specific sample
here is a useful link if you want to learn more about the Pytorch data loading utility
(https://pytorch.org/docs/stable/data.html)

Padding sequences in tensorflow with tf.pad

I am trying to load imdb dataset in python. I want to pad the sequences so that each sequence is of same length. I am currently doing it with numpy. What is a good way to do it in tensorflow with tf.pad. I saw the given here but I dont know how to apply it with a 2 d matrix.
Here is my current code
import tensorflow as tf
from keras.datasets import imdb
max_features = 5000
print('Loading data...')
(x_train, y_train), (x_test, y_test) = imdb.load_data(num_words=max_features)
def padSequence(dataset,max_length):
dataset_p = []
for x in dataset:
if(len(x) <=max_length):
dataset_p.append(np.pad(x,pad_width=(0,max_length-len(x)),mode='constant',constant_values=0))
else:
dataset_p.append(x[0:max_length])
return np.array(x_train_p)
max_length = max(len(x) for x in x_train)
x_train_p = padSequence(x_train,max_length)
x_test_p = padSequence(x_test,max_length)
print("input x shape: " ,x_train_p.shape)
Can someone please help ?
I am using tensorflow 1.0
In Response to the comment:
The padding dimensions are given by
# 'paddings' is [[1, 1,], [2, 2]].
I have a 2 d matrix where every row is of different length. I want to be able to pad to to make them of equal length. In my padSequence(dataset,max_length) function, I get the length of every row with len(x) function. Should I just do the same with tf ? Or is there a way to do it like Keras Function
x_train = keras.preprocessing.sequence.pad_sequences(x_train, maxlen=maxlen)
If you want to use tf.pad, according to me you have to iterate for each row.
Code will be something like this:
max_length = 250
number_of_samples = 5
padded_data = np.ndarray(shape=[number_of_samples, max_length],dtype=np.int32)
sess = tf.InteractiveSession()
for i in range(number_of_samples):
reviewToBePadded = dataSet[i] #dataSet numpy array
paddings = [[0,0], [0, maxLength-len(reviewToBePadded)]]
data_tf = tf.convert_to_tensor(reviewToBePadded,tf.int32)
data_tf = tf.reshape(data_tf,[1,len(reviewToBePadded)])
data_tf = tf.pad(data_tf, paddings, 'CONSTANT')
padded_data[i] = data_tf.eval()
print(padded_data)
sess.close()
New to Python, possibly not the best code. But I just want to explain the concept.

How to predict Label of an email using a trained NB Classifier in sklearn?

I have created a Gaussian Naive Bayes classifier on a email (spam/not spam) dataset and was able to run it successfully. I vectorized the data, divided in it train and test sets and then calculated the accuracy, all the features that are present in the sklearn-Gaussian Naive Bayes classifier.
Now I want to be able to use this classifier to predict "labels" for new emails - whether they are by spam or not.
For example say I have an email. I want to feed it to my classifier and get the prediction as to whether it is a spam or not. How can I achieve this? Please Help.
Code for classifier file.
#!/usr/bin/python
import sys
from time import time
import logging
# Display progress logs on stdout
logging.basicConfig(level = logging.DEBUG, format = '%(asctime)s %(message)s')
sys.path.append("../DatasetProcessing/")
from vectorize_split_dataset import preprocess
### features_train and features_test are the features
for the training and testing datasets, respectively### labels_train and labels_test are the corresponding item labels
features_train, features_test, labels_train, labels_test = preprocess()
#########################################################
from sklearn.naive_bayes import GaussianNB
clf = GaussianNB()
t0 = time()
clf.fit(features_train, labels_train)
pred = clf.predict(features_test)
print("training time:", round(time() - t0, 3), "s")
print(clf.score(features_test, labels_test))
## Printing Metrics
for Training and Testing
print("No. of Testing Features:" + str(len(features_test)))
print("No. of Testing Features Label:" + str(len(labels_test)))
print("No. of Training Features:" + str(len(features_train)))
print("No. of Training Features Label:" + str(len(labels_train)))
print("No. of Predicted Features:" + str(len(pred)))
## Calculating Classifier Performance
from sklearn.metrics import classification_report
y_true = labels_test
y_pred = pred
labels = ['0', '1']
target_names = ['class 0', 'class 1']
print(classification_report(y_true, y_pred, target_names = target_names, labels = labels))
# How to predict label of a new text
new_text = "You won a lottery at UK lottery commission. Reply to claim it"
Code for Vectorization
#!/usr/bin/python
import os
import pickle
import numpy
numpy.random.seed(42)
path = os.path.dirname(os.path.abspath(__file__))
### The words(features) and label_data(labels), already largely processed.###These files should have been created beforehand
feature_data_file = path + "./createdDataset/dataSet.pkl"
label_data_file = path + "./createdDataset/dataLabel.pkl"
feature_data = pickle.load(open(feature_data_file, "rb"))
label_data = pickle.load(open(label_data_file, "rb"))
### test_size is the percentage of events assigned to the test set(the### remainder go into training)### feature matrices changed to dense representations
for compatibility with### classifier functions in versions 0.15.2 and earlier
from sklearn import cross_validation
features_train, features_test, labels_train, labels_test = cross_validation.train_test_split(feature_data, label_data, test_size = 0.1, random_state = 42)
from sklearn.feature_extraction.text import TfidfVectorizer
vectorizer = TfidfVectorizer(sublinear_tf = True, max_df = 0.5, stop_words = 'english')
features_train = vectorizer.fit_transform(features_train)
features_test = vectorizer.transform(features_test)#.toarray()
## feature selection to reduce dimensionality
from sklearn.feature_selection import SelectPercentile, f_classif
selector = SelectPercentile(f_classif, percentile = 5)
selector.fit(features_train, labels_train)
features_train_transformed_reduced = selector.transform(features_train).toarray()
features_test_transformed_reduced = selector.transform(features_test).toarray()
features_train = features_train_transformed_reduced
features_test = features_test_transformed_reduced
def preprocess():
return features_train, features_test, labels_train, labels_test
Code for dataset generation
#!/usr/bin/python
import os
import pickle
import re
import sys
# sys.path.append("../tools/")
""
"
Starter code to process the texts of accuate and inaccurate category to extract
the features and get the documents ready for classification.
The list of all the texts from accurate category are in the accurate_files list
likewise for texts of inaccurate category are in (inaccurate_files)
The data is stored in lists and packed away in pickle files at the end.
"
""
accurate_files = open("./rawDatasetLocation/accurateFiles.txt", "r")
inaccurate_files = open("./rawDatasetLocation/inaccurateFiles.txt", "r")
label_data = []
feature_data = []
### temp_counter is a way to speed up the development--there are### thousands of lines of accurate and inaccurate text, so running over all of them### can take a long time### temp_counter helps you only look at the first 200 lines in the list so you### can iterate your modifications quicker
temp_counter = 0
for name, from_text in [("accurate", accurate_files), ("inaccurate", inaccurate_files)]:
for path in from_text: ###only look at first 200 texts when developing### once everything is working, remove this line to run over full dataset
temp_counter = 1
if temp_counter < 200:
path = os.path.join('..', path[: -1])
print(path)
text = open(path, "r")
line = text.readline()
while line: ###use a
function parseOutText to extract the text from the opened text# stem_text = parseOutText(text)
stem_text = text.readline().strip()
print(stem_text)### use str.replace() to remove any instances of the words# stem_text = stem_text.replace("germani", "")### append the text to feature_data
feature_data.append(stem_text)### append a 0 to label_data
if text is from Sara, and 1
if text is from Chris
if (name == "accurate"):
label_data.append("0")
elif(name == "inaccurate"):
label_data.append("1")
line = text.readline()
text.close()
print("texts processed")
accurate_files.close()
inaccurate_files.close()
pickle.dump(feature_data, open("./createdDataset/dataSet.pkl", "wb"))
pickle.dump(label_data, open("./createdDataset/dataLabel.pkl", "wb"))
Also I want to know whether i can incrementally train the classifier meaning thereby that retrain a created model with newer data for refining the model over time?
I would be really glad if someone can help me out with this. I am really stuck at this point.
You are already using your model to predict labels of emails in your test set. This is what pred = clf.predict(features_test) does. If you want to see these labels, do print pred.
But perhaps you what to know how you can predict labels for emails that you discover in the future and that are not currently in your test set? If so, you can think of your new email(s) as a new test set. As with your previous test set, you will need to run several key processing steps on the data:
1) The first thing you need to do is to generate features for your new email data. The feature generation step is not included in your code above, but will need to occur.
2) You are using a Tfidf vectorizer, which converts a collection of documents to a matrix of Tfidf features based upon term frequency and inverse document frequency. You need to put your new email test feature data through the vectorizer that you fit on your training data.
3) Then your new email test feature data will need to go through dimensionality reduction using the same selector that you fit on your training data.
4) Finally, run predict on your new test data. Use print pred if you want to view the new label(s).
To respond to your final question about iteratively re-training your model, yes you definitely can do this. It's just a matter of selecting a frequency, producing a script that expands your data set with incoming data, then re-running all steps from there, from pre-processing to Tfidf vectorization, to dimensionality reduction, to fitting, and prediction.

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