Categories
Development

Map(), lambda() functions for 2-d arrays

Suppose we’ve a following array:

arr = [[ 5.60241616e+02,  1.01946349e+03,  8.61527813e+01],
 [ 4.10969632e+02 , 9.77019409e+02 , -5.34489688e+01],
 [ 6.10031512e+02, 9.10689615e+01, 1.45066095e+02 ]]

How to print it with rounded elements using map() and lamba() functions?

l = list(map(lambda i: list(map(lambda j: round(j, 2), i)), arr))
print(l)

The result will be the following:

[[560.24, 1019.46, 86.15], 
 [410.97, 977.02, -53.45], 
 [610.03, 91.07, 145.07]]
Categories
Development Featured Review Web Scraping Software

Sequentum Enterprise review

Sequentum Enterprise is a powerful, multi-featured enterprise data pipeline platform and web data extraction solution. Sequentum’s CEO Sarah Mckenna doesn’t like to call it web scraping because, in its description, the web scraping refers to many different types of unmanaged and non-compliant techniques for obtaining web-based datasets. 

Categories
Data Mining

Sklearn, Classification and Regression metrics

in the post will reviewed a number of metrics for evaluating classification and regression models. For that we use the functions we use of the sklearn library. We’ll learn how to generate model data and how to train linear models and evaluate their quality.

Categories
Data Mining

Linear models, Sklearn.linear_model, Regression

In this post we’ll show how to build regression linear models using the sklearn.linear.model module.

See also the post on classification linear models using the sklearn.linear.model module.

Categories
Development

How to print out requestQueue info (Apify) at run time

The docs on requestQueue.getInfo().

After some unsuccessful tries I could have managed to get the requestQueue info output. Note, we run the function inside the Apify runtime environment:

Apify.main(async () => { ... }

Solution 1

We make the function async and add await to the getInfo() Promise call:

async function printRequestQueue (requestQueue){
   var { totalRequestCount, handledRequestCount, pendingRequestCount } = await requestQueue.getInfo();
   console.log(`Request Queue info:` );
   console.log(' - handled :', handledRequestCount);
   console.log(' - pending :', pendingRequestCount);
   console.log(' - total:'  , totalRequestCount); 
}

with the following result:

Request Queue info:
 - handled : 479
 - pending : 312
 - total: 791

Solution 2, using then/catch

In this case we do not need to make our function async since we catch the the getInfo() promise result thru .then(response).

function printRequestQueue (requestQueue){ 
  requestQueue.getInfo().then((response)=> { 
    console.log('total:', response.totalRequestCount); 
    console.log('handled:', response.handledRequestCount);
    console.log('pending:', response.pendingRequestCount);  
    console.log('\nFull response:\n', response); })
 .catch( (error) => console.log(error)); 
}

with the following result:

total: 791
handled: 479
pending: 312

Full response:
 { id: 'queue-name',
  name: 'queue-name',
  userId: null,
  createdAt: 2021-02-26T11:57:00.453Z,
  modifiedAt: 2021-02-26T11:58:47.988Z,
  accessedAt: 2021-02-26T11:58:47.989Z,
  totalRequestCount: 791,
  handledRequestCount: 479,
  pendingRequestCount: 312 
}
Categories
Development

Node.js Cheerio scraper, replace element

let table = $('table');
if ($(table).has('br')) {  				     
    $("br").replaceWith(" ");
}
Categories
Development

DOM selector excluding certain elements

Often we need to select certain html DOM elements excluding ones with certain names/ attributes/ attribute values. Let’s show how to do that.

Categories
Data Mining Development

Linear models, Sklearn.linear_model, Classification

In this post we’ll show how to build classification linear models using the sklearn.linear.model module.

Categories
Data Mining

Adding regularization into Linear Regression model

Regularization is applying a penalty to increasing the magnitude of parameter values in order to reduce overfitting. When you train a model such as a logistic regression model, you are choosing parameters that give you the best fit to the data. This means minimizing the error between what the model predicts for your dependent variable given your data compared to what your dependent variable actually is.

Categories
Data Mining

Cross-validation strategies and their application

In the post we’ll get to know the Cross-validation strategies as from the Sklearn module. We’ll show the methods of how to perform  k-fold cross-validation. All the iPython notebook code is correct for Python 3.6.