How do I select rows from a DataFrame based on column values?

To select rows whose column value equals a scalar, some_value, use ==: To select rows whose column value is in an iterable, some_values, use isin: Combine multiple conditions with &: Note the parentheses. Due to Python’s operator precedence rules, & binds more tightly than <= and >=. Thus, the parentheses in the last example are necessary. Without the parentheses is parsed as which results in a Truth … Read more

How do I select rows from a DataFrame based on column values?

To select rows whose column value equals a scalar, some_value, use ==: To select rows whose column value is in an iterable, some_values, use isin: Combine multiple conditions with &: Note the parentheses. Due to Python’s operator precedence rules, & binds more tightly than <= and >=. Thus, the parentheses in the last example are necessary. Without the parentheses is parsed as which results in a Truth … Read more

Chrome: Uncaught SyntaxError: Unexpected end of input

This particular error is one annoying fact about v8. In most cases your JavaScript is broken in some way. For example missing a } or something like that. Example given, this will yield “Unexpected end of input” too: But the root cause of the problems seems to be that the requested JSON url has a Content-Type of text/html which Chrome apparently tries … Read more

Finding the average of a list

On Python 3.4+ you can use statistics.mean() On older versions of Python you can do On Python 2 you need to convert len to a float to get float division There is no need to use reduce. It is much slower and was removed in Python 3.

Why does z-index not work?

The z-index property only works on elements with a position value other than static (e.g. position: absolute;, position: relative;, or position: fixed). There is also position: sticky; that is supported in Firefox, is prefixed in Safari, worked for a time in older versions of Chrome under a custom flag, and is under consideration by Microsoft to add to their Edge browser.

What is Express.js?

This is over simplifying it, but Express.js is to Node.js what Ruby on Rails or Sinatra is to Ruby. Express 3.x is a light-weight web application framework to help organize your web application into an MVC architecture on the server side. You can use a variety of choices for your templating language (like EJS, Jade, and Dust.js). You can then use a database like MongoDB with Mongoose (for modeling) to provide … Read more