Questions tagged [one-hot-encoding]

One-Hot Encoding is a method to encode categorical variables to numerical data that Machine Learning algorithms can deal with. One-Hot encoding is most used during feature engineering for a ML Model. It converts categorical values into a new categorical column and assign a binary value of 1 or 0 to those columns.

Also known as Dummy Encoding, One-Hot Encoding is a method to encode categorical variables, where no such ordinal relationship exists, to numerical data that Machine Learning algorithms can deal with. One hot encoding is the most widespread approach, and it works very well unless your categorical variable takes on a large number of unique values. One hot encoding creates new, binary columns, indicating the presence of each possible value from the original data. These columns store ones and zeros for each row, indicating the categorical value of that row.

1224 questions
6
votes
1 answer

In preprocessing data with high cardinality, do you hash first or one-hot-encode first?

Hashing reduces dimensionality while one-hot-encoding essentially blows up the feature space by transforming multi-categorical variables into many binary variables. So it seems like they have opposite effects. My questions are: What is the benefit…
5
votes
2 answers

ValueError after attempting to use OneHotEncoder and then normalize values with make_column_transformer

So I was trying to convert my data's timestamps from Unix timestamps to a more readable date format. I created a simple Java program to do so and write to a .csv file, and that went smoothly. I tried using it for my model by one-hot encoding it into…
5
votes
2 answers

One hot encoding from numpy

I am trying to understand values output from an example python tutorial. The output doesent seem to be in any order that I can understand. The particular python lines are causing me trouble : vocab_size = 13 #just to provide all variable values m…
D3181
  • 2,037
  • 5
  • 19
  • 44
5
votes
1 answer

sklearn One Hot Encode. ValueError: For a sparse output, all columns should be a numeric or convertible to a numeric

I am new at coding with sklearn, I need to encode 3 columns of my dtaset, I tried encoding only one column but it sent me an error *ValueError Traceback (most recent call…
Ray Ponce
  • 51
  • 1
  • 3
5
votes
2 answers

How to turn one-hot encoded variables to a single factor in R

In this post HERE they discuss how to one-hot encode a single factor variable in R. I wonder how to reverse to the problem and get a single factor from variables that one-hot encode certain properties?
striatum
  • 1,428
  • 3
  • 14
  • 31
5
votes
2 answers

One-hot encoding using model.matrix

There is something I do not understand in model.matrix. When I enter a single binary variable without an intercept it returns two levels. > temp.data <- data.frame('x' = sample(c('A', 'B'), 1000, replace = TRUE)) > temp.data.table <- model.matrix(…
Kozolovska
  • 1,090
  • 6
  • 14
5
votes
1 answer

How to Assign Feature Names in a OneHotEncoder through Column Transformer

I understand that if I run a OneHotEncoder by itself, I am able to change the feature names that it generates from x1_1, x1_2, etc. by calling .get_feature_names e.g.: encoder.get_feature_names(['Sex', 'AgeGroup']) will change x1_1, x2_2 to…
5
votes
0 answers

How to use ImageDataGenerator with multi-label masks for multi-class image segmentation?

In order to do multiclass segmentation the masks need to be one-hot-encoded. For example if I have a 100 images of shape 224x224x3 with 5 different classes I would have a set of masks with shape (100, 224, 224, 5) i.e the last dimension (the…
5
votes
2 answers

How to save one hot encoder?

I am trying to save a one hot encoder from keras to use it again on different texts but keeping the same encoding. Here is my code : df = pd.read_csv('dataset.csv ') vocab_size = 200000 encoded_docs = [one_hot(d, vocab_size) for d in df.text] How…
CuriousLearner
  • 121
  • 1
  • 7
5
votes
1 answer

One hot encoding of multi label images in keras

I am using PASCAL VOC 2012 dataset for image classification. A few images have multiple labels where as a few of them have single labels as shown below. 0 2007_000027.jpg {'person'} 1 2007_000032.jpg {'aeroplane',…
Sree
  • 973
  • 2
  • 14
  • 32
5
votes
2 answers

"ValueError: could not convert string to float" while using OneHotEncoder for machine learning

I'm using LabelEncoder and OneHotEncoder to handle 'categorical data' in my dataset. In my data set there is a column which can have two values either 'Petrol' or 'Diesel' and I want to encode that column. I'm running this piece of code and its…
Kamal Aujla
  • 327
  • 2
  • 10
5
votes
3 answers

Pandas - get_dummies with value from another column

I have a dataframe like below. The column Mfr Number is a categorical data type. I'd like to preform get_dummies or one hot encoding on it, but instead of filling in the new column with a 1 if it's from that row, I want it to fill in the value from…
Chris Macaluso
  • 1,372
  • 2
  • 14
  • 33
5
votes
2 answers

Prediction After One-hot encoding

I am trying with a sample dataFrame : data = [['Alex','USA',0],['Bob','India',1],['Clarke','SriLanka',0]] df = pd.DataFrame(data,columns=['Name','Country','Traget']) Now from here, I used get_dummies to convert string column to an…
vishal yadav
  • 93
  • 1
  • 7
5
votes
1 answer

How to use Pandas get_dummies on predict data?

After using Pandas get_dummies on 3 categorical columns to get a one hot-encoded Dataframe, I've trained (with some success) a Perceptron model. Now I would like to predict the result from a new observation, that it is not hot-encoded. Is there any…
Hugo
  • 1,558
  • 12
  • 35
  • 68
5
votes
3 answers

how to keep column's names after one hot encoding sklearn?

I am working on the titanic kaggle competition, to deal with categorical data I’ve splited the data into 2 sets: one for numerical variables and the other for categorical variables. After working with sklearn one hot encoding on the set with…