Questions tagged [preprocessing]

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Python - Create many dummy variables from one text variable?

I'm trying to create dummy variables for a variable that has text data in rows. Data in 1st row is: ...
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0answers
134 views

Audio files and their corresponding spectrograms for image classification process

Suppose I have a dataset of audio files that I have to use for whale sound classification. I am choosing the strategy of treating it as an image classification problem by using their corresponding ...
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0answers
16 views

Group data without losing information

Context Imagine that I have a dataset about sending messages. Each row as user_id, a batch_id, a ...
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1answer
1k views

Using pandas get_dummies() on real world unseen data

I made a ML model, trained and tested it with my data containing categorical variables. To create dummy variables I used pd.get_dummies() before the split. I now ...
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1answer
175 views

what is correct way to perform normalization on data in Auto encoder?

working on anomaly detection problem. i'm using auto-encoder to denoise given input. I trained network with normal data(anomaly free). so model predict normal state of given input. Normalization of ...
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55 views

Dummy variables for unseen data in R

I got the following problem: When I trained my model I created my dummy variables(before train-test split) in the following way: ...
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0answers
279 views

Decision Tree - Preprocessing for very sparse features

How do we pre-process data for very sparse features for a decision tree? From this Turi documentation for decision trees It mentioned this: Why chose decision trees? Different kinds of models ...
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1answer
40 views

How to deal with name strings in large data sets for ML?

My data set contains multiple columns with first name, last name, etc. I want to use a classifier model such as Isolation Forest later. Some word embedding techniques were used for longer text ...
2
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1answer
724 views

Why does not log transformation make the data normalized?

Having some skewed features as shown in the following figure. I am trying to imply log transformation to the feature called vBMD(mgHA/cm3). I run the following ...
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1answer
498 views

Mutate with dynamic column names dplyr

Hi I have this dataset (It has many more columns) ...
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1answer
38 views

How to discretize certain features with a feature set?

I am working with typing data with timing features(unit: ms) and some of the features are based on the keyboard keyCodes(positive integers, range:[8, 222]). Currently, I use ...
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0answers
83 views

Image preprocessing: How to resize / align / cut images of various sizes?

I want to create a new dataset for image recognition. If I have Object A that I want to recognize in images, and multiple images of various different sizes, how do I preprocess them so that they ...
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0answers
190 views

Should I remove the trend from timeseries when using DeepAR

I saw that for some other algorithms for timeseries data it is advised to remove trend and seasonality before doing the prediction (ex: ARIMA and LSTM) I figured out from the paper that SageMaker's ...
2
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2answers
7k views

Loading own train data and labels in dataloader using pytorch?

I have x_data and labels separately. How can I combine and load them in the model using torch.utils.data.DataLoader? I have a dataset that I created and the ...
2
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2answers
55 views

How to Normalise features for small datasets?

I am working with a small dataset ( N = 50 ). I would like to normalise my input features. I am facing the following issues: Because of the small size of the dataset the range of training input ...
2
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1answer
90 views

Clustering time series based on monotonic similarity

Context I am involved in a task of clustering 1500 time series of 500 observations into a few number of clusters. The time series share all the same observed property at different spatial locations, ...
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0answers
47 views

Construction Adjacency matrix for GNN

A bit of a novice question, my data comes in the form of 2D hit points, my goal is to perform node/edge classification to find out whether this graph is my signal or background. My question is, when ...
2
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2answers
383 views

How to extract and classify data from a column in excel?

I have a column in an Excel sheet that contains a lot of data separated by || delimiters. The data can be classified to some classes like Entity, IFSC codes, ...
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0answers
23 views

Calculating unaffected data [closed]

Some data sets values are missing. Missing values are spread along 1.5 standard deviation from the median with distribution mean = 0 & variance = 5. How much data would remain unaffected in %. Why?...
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37 views

Checking skewness of variables

I follow a tutorial for the current dataset I'm working on. In this tutorial the target variable is check for skewness, and corrected het for by by taking the log transformation. Hereafter, skewness ...
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2answers
145 views

Pre-processing on MRI images

I have MRI images of brain tumors collected from a hospital (not a benchmark dataset). And I am planning to use them to predict/classify tumour types using a typical machine learning approach: texture ...
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1answer
199 views

LSTM for prediction of next location step - help with standardization

I have a few questions regarding the topic and I hope someone might have experience with any of them. What I am trying to do is train an LSTM network, whose input is a sequence of N steps in a XYZ ...
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0answers
25 views

Specific data formatting techniques for discontiguous time series?

I'm facing a predicting problem for food alerts. The goal is to predict the variables of the most probable alert in the next x days (also any information I could get about future alerts is really ...
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1answer
28 views

Loading Data into DW: Direct Insert from PreProcessing vs PreProcess and then loading from CSV files

I have a preprocessing script (google cloud function) that generates files (stored in Google Drive). I want to load those files in my DW (Big Query). What are the pros and cons of: 1) Running the ...
1
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1answer
149 views

Encoding multiple observations from the same feature space

My data contains multiple observations of categorical feature.The feature space is medical symptoms, so the data for this feature is like : ['fever','pain','yellow skin' .... ] .The amount of symptoms ...
2
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1answer
33 views

Image normalisation methods

I have found some research papers specifying explicitly the normalisation technique they used to get the results. What difference do IMG /255.0 And ...
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0answers
120 views

Remove attributes with missing values exceeding a given threshold in WEKA

I imported csv file into WEKA, i have features that have missing value that has missing value percentage of 70% or above, i want to remove these features by weka or also sort that features by missing ...
1
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1answer
283 views

Cleaning data automatically [closed]

Do you use automatic cleaning tools for data? I mean something similar to h2o.ai's auto ml function but applied to preprocessing data. Or do you always clean data 'by hand'.
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2answers
169 views

data pre-processing before image classification

I'm working on a machine learning project, Images classification (shape: 100 x 100)-> (vector of 10000), I did some pre-processing before applying decision trees algorithm , I got an accuracy of 55 % ...
4
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2answers
846 views

Columntransformer multiple columns with vector inputs

This is perhaps more of a coding question than data science so apologies if this is not the right platform to ask this. My question is related to the sklearn's <...
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1answer
111 views

What is the the cost of combining categorical variables?

I have 2 categorical variables e.g. state and city. Missing are only in city. As opposed to throwing out all observations with missing values for city or throwing out city all together I was ...
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1answer
51 views

Does discretization of continuous features also lose information about distance?

During discretization, it "squashes" nearby values into one bin, losing a little bit of information along the way. But doesn't it also lose information about distances of features? For example, if we ...
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2answers
222 views

Transformation of categorical variables (binary vs numerical)

When using categorical encoding, I see some authors use arbitrary numerical transformation while others use binary transformation. For example, if I have a feature vector with values A, B and c. The ...
0
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1answer
53 views

Is it correct to use non-target values of test set to engineer new features for train set?

Suppose, I have a dataset with a feature_1 value and a target value. Now, I want to engineer a new feature by creating relative value by subtracting mean from each value. Question: Can I (1) use ...
0
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1answer
221 views

LSTM - How to prepare train from a dataset which contains multiple observations for different events

I m using LSTM in a project related to MobiFall dataset which contains falls and daily activitives - such as walking, sitting etc - sensed by accelerometer, gyroscope and orientation sensors in x,y,z ...
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0answers
70 views

How to deal with attributes that can vary arbitrarily for each sample?

Let's say we are trying to classify cars into five different categories. For this, we have a lot of samples described by color, brand, model, year of manufacture and so on. For instance, imagine ...
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0answers
232 views

Audio signal signal processing for background noise reduction or removal

I am performing simple audio recognition using tensor-flow to spot key word or hot word detection. The graph takes the microphone input directly and performs "Audio spectrometer --> mfcc's --> and ...
0
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1answer
531 views

pandas: How to impute the categorical column by the nearest neighbors?

I've a categorical column with values such as right('r'), left('l') and straight('s'). I expect these to have a continuum periods in the data and want to impute nans with the most plausible value in ...
1
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3answers
99 views

Is there any tool for data visualization and manipulation?

I have a time series data set that I need to manually label them for supervised learning. What I am doing now is using excel to plot, and when I see the pattern that I want, I hover over the data on ...
0
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1answer
49 views

Missing Values in Classification

I'm working on a classification problem. I'm trying to build a model which can predict if a bank client will get a loan or not. Some of clients have co-borrower and the majority don't. I also have ...
16
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3answers
4k views

Difference between OrdinalEncoder and LabelEncoder

I was going through the official documentation of scikit-learn learn after going through a book on ML and came across the following thing: In the Documentation it is given about ...
2
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2answers
117 views

Can preprocessing the whole population cause data leakage?

Introduction I understand the problem of data leakage that could be caused by the preprocessing step when our training and test sets are just samples of an unknown population. The preprocessing ...
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0answers
68 views

Any tool that can help on manually label a time series data please?

i am working with a 10 years weekly financial time series data set, which has the standard format date open high low close volume. i would like to manually label (classify) the data set with label/...
3
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2answers
883 views

A single column has many values per row, separated by a comma. How to create an individual column for each of these?

As you can see below, I have a column called code with multiple values per row, separated by a comma. How can I create a column for each of these codes and make ...
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0answers
139 views

How standardizing and/or log transformation affect prediction result in machine learning models

I recently ran an elastic net model on my data. My predictors are mostly skewed. I found my model perform slightly better when I standardize on log-transformed data than standardizing on original data....
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0answers
153 views

Lowercase texts before tokenizing as pre-processing step for alignment

I am pre-processing some texts and I wonder what the best practice is when preparing your texts for word alignment. I don't know how aligners such as fast align and GIZA++ work under the hood, but I ...
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0answers
129 views

Transposing a dataframe (time-series)

I'm working on event-forecasting problem for a supermarket, and the data frame I have looks like (sorry for formatting): ...
20
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3answers
13k views

StandardScaler before and after splitting data

When I was reading about using StandardScaler, most of the recommendations were saying that you should use StandardScaler before ...
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0answers
41 views

Normalize data with uneven groups?

I have a dataset with 3 independent variables [city, industry, amount] and wish to normalize the amount. But I wish to do it with respect to industry and city. Simply grouping by the city and industry ...
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0answers
13 views

Are there some resources for filters specifically applicable in big data applications? [closed]

Are there some resources for filters specifically applicable in big data applications? Particularly, are there major differences between filter design for other domains and filter design for data ...