Python Tutorial: Reading, inspecting, & cleaning data from csv files
Want to learn more? Take the full course at https://learn.datacamp.com/courses/importing-and-managing-financial-data-in-python at your own pace. More than a video, you'll learn hands-on coding & quickly apply skills to your daily work.
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Hi, and welcome to the course "importing and managing financial data in Python"! My name is Stefan Jansen and I'll be your instructor for this course. I have been working in international finance, investment and economic research for over 15 years, and have been using python for data science for over five years. I advice companies on data strategy, machine learning, and artificial intelligence in various industries.
In this first video, you will learn more about how to import data from CSV files in Python.
When moving data from one format to another, you need to make sure that all information is accurately captured, and nothing gets lost in the process.
To illustrate how to address some issues that often arise when you import data, we will use a file with info on companies listed on the AmEx Stock Exchange. This file contains a company’s name and stock ticker, which is the symbol needed to get price and other information about a company from an exchange, its sector, industry and IPO year, that is the year when it started trading on a stock exchange. It also contains the most recent share price, and the market capitalization, which the combined value of all its shares, and the date of the latest update.
A quick look at the file reveals a few missing values: they are identified by the string ‘n/a’. You can also see that this CSV file contains three different types of data:
4 columns contain text data, also called ‘strings’
3 columns contain numeric data, and
one column has date information
Pandas assigns a different data type to each column, and stores this information in a property called ‘dtype’. The dtype of a column affects how you can use its content in calculation and visualization.
In particular, pandas distinguishes b
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