The newest version of data.table has hit CRAN, and there are lots of great new features. Among them, a %notin% function, a new let function that can be used instead of := ( I wasn’t too fussed about this originally but have tried it a few ti... [Read more...]

Following on from my last post, here is a bit more about the use of .I in data.table. Scenario : you want to obtain either the first, or last row, from a set of rows that belong to a particular group. For example, for a patient admitted to ... [Read more...]

In this post I’m using a small extract from the SIMD2020 dataset to figure out what the special operator .I does. Files and code are on github if you’re interested # files and code : https://github.com/johnmackintosh/DT_dot_I library(data.t... [Read more...]

I have been toying with some of the advent of code challenges (I am way behind though!). For day 5, I had to create a function, and I’m writing this up, because it’s an example of a non-equi join between two tables. In this particular sitat... [Read more...]

Last week I had to talk my colleagues through the architecture of an R project that we’ve been working on for a while. This is a large project, as we make our first moves into Reproducible Analystic Pipelines, and makes heavy use of the {tar... [Read more...]

We all need to pivot data at some point, so these are just some notes for my own benefit really, because gather and spread are no longer in favour within tidyr. NB - this post has been updated with collapsible sections to show/hide the data ... [Read more...]

We all need to pivot data at some point, so these are just some notes for my own benefit really, because gather and spread are no longer in favour within tidyr. I tended to only ever need gather, and nearly always relied on the same key and ... [Read more...]

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Here’s a quick example of needing to make some updates to an existing column in a data.table. For reasons I don’t want to get into (involving MS Word :/) I had to change a couple of columns from factor to character, and swap out the ampersan... [Read more...]

Several of my recent blog posts have been focussed on using {purrr} and {glue} to programatically query a database. This is something I’d been wanting to achieve for some time, but my efforts got put on hold when COVID-19 came along. The ge... [Read more...]

You want to run a query over multiple tables in your database / warehouse and then process and visualise the combined results of those queries. You need to be able to switch between servers, databases, schemas and tables, selecting different... [Read more...]

I’m looking into creating some functions to make it easier to carry out quality checks on our database tables. I’m using SQL Server, where tables are referred to in a [database].[schema].[tablename] format, although you can forgo some of this... [Read more...]

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It’s almost 2 weeks since I had my first package successfully submitted to CRAN. The runcharter package is special to me for lots of reasons - it was a tough problem to crack, and it’s one I’ve worked on with a variety of tools over the year... [Read more...]