Explains the asterisk operator * and ** usage and its useful applications.

Image from unsplash.com

Common Usage

def my_func(*args,**kwargs):
print(args)
print(kwargs)
my_func(1,2,3,a=4,b=5)
args:(1, 2, 3)
kwargs:{'a': 4, 'b': 5}
my_func(1,2,3,a=4,b=5,6)

The meaning of single * and double **


The Rabbit And The Turtle — By Charles Zhu, my 6 years old son

People said Python is slow, how slow it can be

import numpy as np
np.random.seed(0)
values = np.random.randint(1, 100, size=1000000)
def get_reciprocal(values):
output = np.empty(len(values))
for i in range(len(values)):
output[i] = 1.0/values[i]
%timeit get_reciprocal(values)
3.37…


Python packages installation steps for Azure Machine Learning

Azure Machine Learning


A retrospection of the book “The Phoenix Project”.

Image by Natalie Pedigo

Plan work for next week, only


An analysis of why some technologies fail and why some last very long. What should we consider before adopting new technology?

Image by Gevorg Avetisyan of unsplash


Why we need to pick features for a machine learning model, how to use Mutual Information to select features, and use Mutual information tools from the Scikit-Learn package.

Image from unsplash.com

The feature selection problem


Three common mistakes could be made in your Spark PySpark projects. Those mistakes may confuse your colleagues and also make you pull your hair out.

Image by my boy, Charles Zhu

Use Concatenated Spark SQL string in functions

# create a view from spark dataframe 
sdf.gud.createOrReplaceTempView('sdf_view')
# define you sql query as a string
sql_string = "select * from sdf_view"
# execute the spark SQL
result_df = spark.sql(sqlQuery = sql_string)


Understand how Decision Tree Classifier works in plain language and minimum math equations. Figure out how Gini Impurity and Information Gain works from scratch.

By my son, Charles Zhu

How decision tree works


Photo by Tech Daily on Unsplash


  1. Find a crypto price API or scrape the web.
  2. Send out mail if the pice is meet the rule, say, drop 20%.

Get the real-time price

Andrew Zhu

Data Scientist @ Microsoft Redmond, the daddy of two kids, husband, programmer, blogger, fixer.

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