NFeature | Simple feature configuration and availability-control | Frontend Framework library
kandi X-RAY | NFeature Summary
kandi X-RAY | NFeature Summary
Simple feature configuration and availability-control for .NET. Please help me to improve the quality of NFeature by reporting issues here on GitHub.
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QUESTION
I have the following document for which I need to do mapping for elasticsearch
...ANSWER
Answered 2021-May-18 at 07:35There is no need to specify any particular mapping for array values.
If you will not define any explicit mapping, then the rows
field will be dynamically added as of the text
data type
There is no data type that is defined for arrays in elasticsearch. You just need to make sure that the rows
field contains the same type of data
Adding a working example with index data, search query, and search result
Index Mapping:
QUESTION
I am working on a machine learning problem, where I have a lot of zipcodes (~8k unique values) in my data set. Thus I decided to hash the values into a smaller feature space instead of using something like OHE.
The problem I encountered was a very small percentage (20%) of unique rows in my hash, which basically means from my understanding, that I have a lot of duplicates/collisions. Even though I increased the features in my hash table to ~200, I never got more than 20% of unique values. This does not make sense to me, since with a growing number of columns in my hash, more unique combinations should be possible
I used the following code to hash my zip codes with scikit and calculate the collisions based on unique vales in the last array:
...ANSWER
Answered 2021-Apr-27 at 14:42That very first 2
in the transformed data should be a clue. I think you'll also find that many of the columns are all-zero.
From the documentation,
Each sample must be iterable...
So the hasher is treating the zip code '86916'
as the collection of elements 8
, 6
, 9
, 1
, 6
, and you only get ten nonzero columns (the first column presumably being the 6
, which appears twice, as noted at the beginning). You should be able to rectify this by reshaping the input to be 2-dimensional.
QUESTION
I'm looking at the MediaEval 2018 memorability challenge (here).
One of the features they describe is ORB features. I got the data from the challenge, and I'm trying to understand how the ORB data works.
If I run this code:
...ANSWER
Answered 2021-Mar-14 at 19:01I cannot determine the meaning of every field, but I think I can guess it for some:
- First tuple is x, y position of the feature (most likely pixel coordinates)
- 31 is the size of the feature, given by the patch size
- 169 should be the orientation of the feature in degrees
- The list at the end gives the description of the feature. This is generated by the BRIEF descriptor. It's a list of 32 8 bit values. If you generate the bit pattern for each of these numbers you end up with 256 1's or 0's. This is the binary feature description that is used for matching.
QUESTION
I want to get mapping to work using a Picamera. I have a Raspberry Pi running a cv_camera_node and an Ubuntu 20.04.1 running roscore
, as well as, slam and rviz. I have OpenCV 4.2.0 and installed the following version of orb-slam2: https://github.com/appliedAI-Initiative/orb_slam_2_ros. I am running ROS Noetic. I have wrote the following launch file for slam:
ANSWER
Answered 2021-Feb-10 at 19:02Maybe your camera isn't getting picked up. You are using cv_camera_node meaning that the default topic will be cv_camera but orb_slam2 requires just camera. To solve this, go into the cv_camera_node.cpp which will look like this:
QUESTION
My full code:
...ANSWER
Answered 2021-Jan-27 at 13:45Let me start with a minor change with your code.
When you initialized using \
separator, your code will work only for Windows.
QUESTION
I am using a MLP model for classification.
When I predict for new data, I want to keep only those predictions whose probability of prediction is larger than 0.5, and change all other predictions into class 0.
How can I do it in keras ?
I'm using using last layer as follows
model.add(layers.Dense(7 , activation='softmax'))
Is it meaningful to get predictions with probability larger than 0.5 using the softmax?
...ANSWER
Answered 2021-Jan-25 at 11:55Softmax function outputs probabilities. So in your case you will have 7 classes and their probability sum will be equal to 1.
Now consider a case [0.1, 0.1, 0.1, 0.1, 0.1, 0.2, 0.3]
which is the output of the softmax. Appyling a threshold in that case would not make sense as you can see.
Threshold 0.5 has nothing to do with n-classed predictions. It is something special for binary classification.
For to get classes, you should use argmax.
Edit: If you want to drop your predictions if they are under a certain threshold, you can use, but that's not a correct way to deal with multi-class predictions:
QUESTION
model = Sequential()
nFeatures = X.shape[1]
model.add(Dense(20,
input_dim=nFeatures,
activation="relu",
kernel_initializer="random_normal",
bias_initializer="zeros"))
nOutput = y.shape[1]
model.add(Dense(nOutput,
activation="softmax",
kernel_initializer="random_normal",
bias_initializer="zeros"))
model.compile(optimizer="adam",
loss="categorical_crossentropy",
metrics=["categorical_accuracy"])
model.summary()
...ANSWER
Answered 2020-Dec-22 at 13:08model = Sequential()
QUESTION
Consider a plotly figure where you can select polynomial features for a line fit using JupyterDash:
If you select an area and then choose another number for polynomial features, the figure goes from this:
... and back to this again:
So, how can you set things up so that the figure displays the same area of the figure every time you select another number of features and trigger another callback?
Complete code: ...ANSWER
Answered 2020-Sep-14 at 07:48This is surprisingly easy and just adds to the power and flexibility of Plotly and Dash. Just add
QUESTION
When running grid search on Inverse of regularization strength parameter and number of nearest neighbors parameter for logistic regression , linear SVM and K nearest neighbors classifier , The best parameters obtained from gridsearch are not really the best when verifying manually by training on same training data set. Code below
...ANSWER
Answered 2020-Oct-08 at 07:21Hyperparameter tuning is performed on the validation (development) set, not on the training set.
Grid Search Cross-Validation is using the K-Fold strategy to build a validation set that is used only for validation, not for training.
You are manually performing training and validation on the same set which is an incorrect approach.
QUESTION
ORB doesn't find keypoints near the edge of an image and I don't understand why. It seems worse that SIFT and SURF and I would expect the opposite.
If I understand correctly then SIFT/SURF use a 16x16 and 20x20 square block respectedly around the test-point so I would expect them not to find keypoints 8 and 10 pixels from an edge. FAST/ORB uses a circle of diameter 7 around the test-point so I expected it to find keypoints even closer to the edge, perhaps as close as 4 pixels (though I think the associated algorithm, BRIEF, to describe keypoints uses a larger window so this would remove some keypoints).
An experiment makes nonsense of my prediction. The minimum distance from the edge in my experiments vary with the size and spacing of the squares but examples are
- SIFT .. 5 pixels
- SURF .. 15 pixels
- ORB .. 39 pixels
Can anyone explain why?
The code I used is below. I drew a grid of squares and applied a Gaussian blur. I expected the algorithms to latch onto the corners but they found the centres of the squares and some artifacts.
...ANSWER
Answered 2020-Aug-31 at 09:26Usually, keypoints at the edge of the image are not useful for most applications. Consider e.g. a moving car or a plane for aerial images. Points at the image border are often not visible in the following frame. When calculating 3D reconstructions of objects most of the time the object of interest lies in the center of the image. Also the fact you mentioned, that most feature detectors work with areas of interest around pixels is important since these regions could give unwanted effects at the image border.
Going into the source code of OpenCV ORB (848-849) uses a function with an edgeThreshold
that can be defined using cv::ORB::create()
and is set to a default value of 31 pixels. "This is size of the border where the features are not detected. It should roughly match the patchSize parameter."
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