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Questions tagged [machine-learning]

Methods and principles of building "computer systems that automatically improve with experience."

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3 views

How do concatenate over many datasets?

I am working on a project where I would like to take two timeseries datasets and train a machine learning model. Say for example, APPL stock performance and MSFT. These are two different excel ...
9
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1answer
657 views

Using Vowpal Wabbit for NER

The Vowpal Wabbit (VW) apparently supports sequence tagging functionality via SEARN. The problem is that I cannot find anywhere detailed parameter list with explanations and with some examples. The ...
2
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1answer
75 views

Time horizon T in policy gradients (actor-critic)

I am currently going through the Berkeley lectures on Reinforcement Learning. Specifically, I am at slide 5 of this lecture. At the bottom of that slide, the gradient of the expected sum of rewards ...
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0answers
8 views

IndexError: too many indices for array when switching dataset to MNIST

I am trying to run a Transfer Learning Code from Github Section 9. Transfer learning for large image classification. I have gotten the original code to work with the flower dataset and inception v3. I ...
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3answers
71 views

Assigning a value to Y for regression

I'm creating a system to evaluate a risk level that grows as it approaches in time to the crisis event. This risk level ranges from 0 to 100, it's a self made index, totally arbitrary. I have a ...
3
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1answer
24 views

K Nearest Neighbour with different distance matrix to each datapoint

I'm wondering if there is library support in python (such as sklearn) for doing KNN on a data set that has a custom distance matrix (positive definite) for each data point (x is a query point, $x_i$ ...
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0answers
6 views

Facial Recognition Using One shot Learning Research Paper

1) I am looking for a latest Research Paper for "Facial Recognition Using One shot Learning" for my semester Project. I want to implement that paper and want to improve that. i have searched on ...
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0answers
7 views

Variational auto-encoders for text generation

How are the variational auto-encoders used for text generation? Can variational auto-encoders be used for character based text generation?
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1answer
14 views

Having trouble figuring out how loss was calculated for SQuAD task in BERT paper

The BERT Paper https://arxiv.org/pdf/1810.04805.pdf Section 4.2 covers the SQuAD training. So from my understanding, there are two extra parameters trained, they are two vectors with the same ...
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1answer
74 views

Combine results from multiple models

I am using chunks of 100000 rows at a time from the CSV file to train the a simple LASSO model. How do i combine all of these models trained from these different chunks? I would like to use all ...
6
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2answers
180 views

How to plot logistic regression decision boundary?

I am running logistic regression on a small dataset which looks like this: After implementing gradient descent and the cost function, I am getting a 100% accuracy in the prediction stage, However I ...
2
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1answer
273 views

Is it appropriate to use polar images as input to CNNs? Or must they be Cartesian transformed first?

I have built a convolutional neural net which trains on data originally represented in polar space (measurements are a function of angle and distance). My pipeline begins by converting coordinates to ...
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2answers
191 views

Python Code to find the number of hapax legomena in a Text or Words_List

In corpus linguistics, a hapax legomenon is a word that occurs only once within a context, either in the written record of an entire language, in the works of an author, or in a single text. The term ...
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1answer
24 views

Books on time series and sequence classification

Though I have been using traditional machine learning algorithms (Regression and Classification) , I have no experience of using Time series and would like to understand what is time series and ...
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0answers
12 views

fancyimpute - crashes my Python runtime/environment every time I use the package

I'm trying to impute null values in my data using fancyimpute python package. First, as suggested by this stackoverflow question, I converted my dataframe to numpy array in order for ...
2
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2answers
342 views

Perceptron - Which step function to choose

I'm studying Perceptron algorithm. Some books use this step function 1 if x>=0 else -1 where x is a dot product between the weights w and a sample x. Other ...
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1answer
46 views

Need recommandations of using timing variables for forecasting sales

I have a data.table that contains many timing variables. Date: it gives the date of Sales Promo2(week, year): It describes the calendar week and the year when the store has started to participate in ...
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0answers
10 views

LASSO Regression using Panel Data

I have panel data for 3 countries, ranging over 3 years. The dataset is called CarProduction ...
4
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2answers
6k views

Multivariate Time-Series Clustering

I have a streaming data along with timestamp dataset that looks like this: 1.png Timestamp can be inclusive of "seconds" too, but the data may or may not change every second. it depends on the ...
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1answer
37 views
3
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1answer
35 views

Lightgbm vs xgboost vs catboost

I've seen that in Kaggle competitions people are using lightgbms where they used to use xgboost. My question is: when would you rather use xgboost instead of lightgbm? What about catboost?
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1answer
37 views

A weird result from a recommender system

Say there're the top 10 most popular items among 100 sales products and about 100k users regularly purchase items on daily basis. ...
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1answer
18 views

Given is the result of the model performance. Help me with this MCQ

You also evaluate your model on the test set, and find the following: Human-level performance 0.1% Training set error 2.0% Dev set error 2.1% Test set error 7.0% What does this mean? (Check the ...
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2answers
373 views

Random Forest Classifier - KFold CV Tunes Very Deep Trees --> Overfitting?

I'm tuning a random forest in python and am wondering if/why my model is overfit. The dataset is described below: 1700 Positive Cases / 54000 total cases ~ 3.2% (unbalanced) 50 Numerical Features,~...
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2answers
15 views

Can feedback loops occur in machine learning that cause the model to become less precise?

In discussions about ML algorithms, in for instance crime prediction, it is often claimed by non-experts that there are problems with feedback loops causing the model to become biased and give the ...
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1answer
27 views

algorithm to predict numeric values with sklearn

I'm new to ML and trying to learn it. I scraped information (using python) from a website where people try to sell their cars. I put data in a pandas data frame. Now I'm wondering how should I predict ...
2
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1answer
20 views

how to implement a hierarchical clustering technique using parallel execution in R

In R, currently to implement wards method for hierarchical clustering, I use the following code - results <- hclust(data, "ward.D2"). However as my data size has ...
2
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1answer
59 views

Survival Analysis: Pseudo Observation Vs Stratified Cox Regression. Which one is better?

I've been looking into the Cox Regression method for Survival Analysis in Churn Prediction. Cox regression will allow us to determine the probability that a subscriber will unsubscribe after a time $t$...
5
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1answer
74 views

Why does a machine learning algorithm need a bias?

The first line of section 2.7.3 in Mitchell's Machine Learning is: "A Learner that makes no prior assumptions regarding the identity of the target concept has no rational basis for classifying any ...
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1answer
22 views

What is a basic object detection/localization ML algorithm that can be used for my relatively simple image set?

I have a relatively simple object localization task. I have an image set that are either uniform or contain an 'object' consisting of a black circular shape at some position in the image. The labels ...
5
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3answers
2k views

Early stopping on validation loss or on accuracy?

I am currently training a neural network and I cannot decide which to use to implement my Early Stopping criteria: validation loss or a metrics like accuracy/f1score/auc/whatever calculated on the ...
4
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2answers
40 views

How do I decide if I need to go for Normalization and not Standardization or vice-versa?

While designing a ML model, how do I decide if I need to go for Normalization and not Standardization or vice-versa? On what factor is this decision made?
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0answers
15 views

Dynamic pricing models when there are a lot of products with low demand

For products with high demand and much stock, there are several algorithms that work for dynamic pricing. However, when selling many different products in the same category and demand for each one is ...
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0answers
14 views

Recommender system based on user attributs [on hold]

I am working on a case study of a bank , I want to recommend product for other users based on users similarities This are the information i have: Age, Gender, City, Nationality, socio-professional ...
0
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1answer
34 views

How exactly do I extract the important features from strings for machine learning?

Forgive me for my ignorance. Linked below is an image of my dataset with 1000 tuples. https://i.stack.imgur.com/WHIlx.png I have the following questions (1) How exactly do I go about extracting ...
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0answers
15 views

How do I implement stochastic gradient descent correctly?

I'm trying to implement stochastic gradient descent in MATLAB however I am not seeing any convergence. Mini-batch gradient descent worked as expected so I think that the cost function and gradient ...
5
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2answers
4k views

Recommender system based on purchase history, not ratings

I'm exploring options for recommender systems optimized for the insurance industry, which would take into account i) product holdings ii) user characteristics (segment, age, affluence, etc.). I ...
1
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1answer
93 views

Dataset of extremely low-dimensional images for PCA

I am looking for a public data-set of images that differ from each other only slightly, so that after applying PCA they can be reconstructed with a small error from ...
1
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1answer
13 views

With a MLP (regression), is it appropriate to initialize bias in the final layer to be a value near the expected mean?

For instance, when predicting IQ in a population you would expect the mean to be 100. If you initialize the bias in the final layer you are basically giving the network a head start, telling it in ...
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1answer
65 views

Data Augmentation for Regression ANN with low Sample Size

There is a Dataset of 65 tuples. I want to Augment new Data from this set and validate my ANN on the original Data. Is there a possibility, that my ANN already overfits on the augmentet Data. For ...
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1answer
32 views

predicition for a specific month

I am attempting to build a predictive model based on the past historical data. I have details of specific machine failure based on the past year data. I have data from some months of 2016 and from ...
5
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3answers
3k views

Why do we use a Gaussian kernel as a similarity metric?

In graph-based clustering, why is it preferred to use the Gaussian kernel rather than the distance between two points as the similarity metric?
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1answer
68 views

Derivation of dz[1] for backpropagation

Can anyone mathematically prove this equation given the values of $dz^{[2]}$, $W^{[2]}$, $z^{[1]}$ and the activation function $g^{[1]}$ $dz^{[1]} = w^{[2]T}dz^{[2]} * g^{[1]'}(z^{[1]})$
5
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2answers
42 views

how to check the distribution of the training set and testing set are similar

I have been playing the Kaggle Competition and I find there is a situation that the distribution of the training set and testing set are different, so I am wondering how to check the distribution of ...
1
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1answer
31 views

Boostrap parameter in random forest regressor?

There's one parameter in RandomForestRegressor which is bootstrap. By default bootstrap=True bootstrap : boolean, optional (...
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0answers
19 views

A K-means with preferential directions [on hold]

I would like to know if there is any K-means, or similar, clustering algorithm that I could give different weights for certain directions. For example, things on right side have a much heavier weight ...
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0answers
21 views

How to build an AI powered search engine [on hold]

I am looking to develop a search engine drived by AI for an ecommerce web app, The aim of that work is to considere the user preferences when responding to the request of the user just like the ...
0
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1answer
46 views

Similar Candidate Recommendations

I've just embarked on a project to recommend similar candidates to employers for a website that offers employers the ability to search its CV database. My background is in engineering research on ...
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1answer
88 views

Sequence models word2vec

I am working on data-set with more than 100,000 records. This is how the data looks like: ...
3
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1answer
35 views

How to find relation between N components and predict the value of any one component using the predicted relation?

I am new to Machine learning and trying to learn by practicing. I have a situation where I am reading a set of N data. Each of N data will have independent state at any moment of time. I want to use ...