课程

Writing Efficient R Code

中级技能水平

更新时间 2023年1月

Learn to write faster R code, discover benchmarking and profiling, and unlock the secrets of parallel programming.

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RProgramming

4小时

14 视频

43 道练习

3,100 XP

56,924

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课程描述

The beauty of R is that it is built for performing data analysis. The downside is that sometimes R can be slow, thereby obstructing our analysis. For this reason, it is essential to become familiar with the main techniques for speeding up your analysis, so you can reduce computational time and get insights as quickly as possible.

先决条件

1

The Art of Benchmarking

In order to make your code go faster, you need to know how long it takes to run. This chapter introduces the idea of benchmarking your code.

Benchmarking

Comparing read times of CSV and RDS files

Operational differences: "<-" and "="

Elapsed time

Relative time

How good is your machine?

DataCamp hardware

Benchmark DataCamp's machine

2

Fine Tuning: Efficient Base R

R is flexible because you can often solve a single problem in many different ways. Some ways can be several orders of magnitude faster than the others. This chapter teaches you how to write fast base R code.

Memory allocation

Why is this piece of code slow?

Timings - growing a vector

Timings - pre-allocation

Importance of vectorizing your code

Vectorized code: multiplication

Vectorized code: calculating a log-sum

Data frames and matrices

Data frames vs. matrices

Data frames and matrices - column selection

Selecting a row in a data frame

Row timings

3

Diagnosing Problems: Code Profiling

Profiling helps you locate the bottlenecks in your code. This chapter teaches you how to visualize the bottlenecks using the profvis package.

What is code profiling

Profiling a function

Where's the hold-up?

Profvis in action

Profvis: Larger example

Change the data frame to a matrix

Calculating row sums

Use && instead of &

Monopoly overview

4

Turbo Charged Code: Parallel Programming

Some problems can be solved faster using multiple cores on your machine. This chapter shows you how to write R code that runs in parallel.

CPUs - why do we have more than one

How many cores does this machine have?

What sort of problems benefit from parallel computing?

Can this loop run in parallel (1)?

Can this loop run in parallel (2)?

The parallel package - parApply

Moving to parallel programming

Moving to parApply

The parallel package - parSapply

Using parSapply()

Timings parSapply()

You can write efficient R code!

Writing Efficient R Code

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