Lemuras 1.2.2

A small Python library to deal with big tables

Lemuras

Sometimes you cannot or don't want to use Pandas or similar advanced tool for data analysis, but still have a need to manipulate large tables with code. In such cases you can use Lemuras – it is a pure Python library without external dependencies. And if you have some experience of Pandas or SQL, then you can easily work with Lemuras.

Again, this library may be considered as a simplified analogue of Pandas, but not as a replacement. However, Lemuras is capable of processing an operation on a few tables with several thousands of rows in less than a second on a simple web server. So, if you need a tiny library to generate analytical reports or convert table formats, Lemuras is a good choice!

Features

• Integration with Jupyter IPython Notebook: Lemuras objects are printed as nice tables.
• Save / load CSV files, JSON, HTML tables, SQL (both query result and table creation code).
• Automatic columns types detection, simple type conversion.
• Access, add, edit, delete cells, rows, columns. Apply custom of built-in functions, lambdas, sort the data, iterate over rows.
• Advanced processing of columns: you can take any table column, apply any function or lambda, do math with several columns and discrete values, compare them, check existing in other columns or lists, filter a table by it, or add it to a table, etc... In other words, you can do anything!
• Grouping by none, one, or multiple columns, aggregation with built-in or user-defined functions and lambdas for specified or just all the columns.
• Merge (Join): inner / left / right / outer.
• Tables concatenation and appending.
• Pivot tables creation.

It is tasted on Python 2.7 and Python 3.4-3.7

Examples

All the features are described in notebook examples:

1. Basic things – access to columns, cells, rows; add, delete, change their values; also filtering and sorting. 1.5) Functions applying – apply functions or lambda expressions to columns or tables, change types, aggregate values, use your own or one of lots predefined useful functions (oncluding statistical ones).
2. Group by – grouping and combining (aggregating).
3. Merge / Join – such types: inner, outer, left, right.
4. Pivot table – create new tables with columns, rows and cells from another table.
5. Tables Concatenate / Append – simple tables concatenation and appending.
6. Types, Read/Write, CSV, SQL, JSON, HTML – description of Lemuras supported data types, saving to and loading from CSV, SQL, JSON, HTML formats.

In addition, there are several complex examples of solving a real world problems:

1. Retargeting results report

2. Filtration by location area

3. OLAP reports parser with CSV, TSV, and even XLS support

The code of Lemuras is well-commented, also there are many unit-tests, so, you can easily find useful information there. Contributions are welcome.