Clojure Report Generation

The entire code from this blog post is here. I will chunk it up to explain:

Working with collections in Clojure makes programming such a natural experience. Especially when you want to report on your data. Many different data stores have libraries which make getting information into Clojure trivial. They often use a collection of maps where map keys are the "column" names and the values are the data. The following generate-report function should work on any collection of maps.

Above I am taking a set of query results (i.e. a collection of maps) and any number of report items. A small sample of one of the maps in the collections with which I'm dealing is here.

The first thing to do is grab the headers. These are just the firsts of each report item. Pretty simple. The process function takes the keys from each report-item and applies manipulation-function to the result of (get-in % ks). Process returns a new function that takes a query-result, so I can map it over every report-item to get columns as a seq of functions. Finally to get rows, I use apply juxt to call every function in columns on each query-result to get a vector of each of the results of those calls.

You can tell from the doc string what report-items are supposed to look like, so I will show you two of my reports. The first one uses the generate-report function to put its :headers and :rows into an html table.

The code above is all that is required to create this:

Granted the manipulation functions in each report-item are doing most of the display work, the generate-report function makes it easier to focus on what matters out of each map in the collection of query-results.

The reason I wanted to break out the generate-report function is that reports on the same data might not always look the same. The next example looks at a report that needs to export to a spreadsheet. For the HTML table, I wanted to shorten up some of the fields, by displaying "Lastname, First initial." The title tag for the td displays the entire name if the user needs to know. However, once exported, there are no title tags, so the user would have no idea if he was looking at John Smith's or Jessica Smith's score. In xls-report I use a function to display all of the parts of the operators and evaluators which together constitute a unique identifier (see employee-display).

This report demonstrates the use of the nested maps by getting out the vector of [:client :account-numer] and [:client :account-name]. These are passed to a get-in call which gets me the :client of each score, and then the :account-number and :account-name of that result. Now the *.xls that gets saved can be sorted by either account-number or account-name.

Definitely handy stuff. I'm really starting to love this whole idea that code is data and vice versa.


clojure map-keys

Someone in #clojure was asking about how to case-insensitively check the keys of a map. The best answer anyone present at the time came up with was pre-processing the map by naming, lowering, and keywordifying the keywords. We then found out the asker was looking for keys in nested maps, so I wrote a function for that.

After writing the function I realized I could extract the lowering function and let it take a function to apply to all keys of m and all keys in m's vals.

Here is the map-keys function with the lower-key function extracted. I run it on some goofy data at the end. Try it in a REPL.


Clojure Dates with Java Interop

I really just want to test how an embedded gist looks in blogger. I thought I would do it with a simple function I wrote to test if a date object was between two other date objects in clojure. I found how to do it in Java on stackoverflow, so I took advantage of clojure's java interop, and this is what we get:


Optimize your Optimization.

I constantly am looking for a better way to write my functions. I want them to be fast, flexible and readable. However, in the fast department, I also want to write them fast. Tradeoffs are always made in programming. It hit me recently to optimize my optimizations. That is, focus my optimization on the things used the most.

I was working out a function in a web app controller which gets accessed every time there is a write operation on the database. I was trying to figure out how to perform less reads to get the data into the write function. This is when I realized that the write operations would be done, on average, less than once a day. I think I can handle two or three reads per write in that frequency.

Now I can move on, but while I'm working on optimizing things that happen every second, what do you think of this approach? Am I caring too little? Should I be concerned of anything? How would you approach it?

33,000 cases of beer on the wall. . .



Best In Class: Clojure vs Ruby & Scala - Transient Newsgroups

Best In Class: Clojure vs Ruby & Scala - Transient Newsgroups

This was great. I keep seeing so many reasons that Clojure is awesome. It's no wonder the language is growing so fast. I want to take this approach, but instead of searching the file contents, I want to display all images in a directory in chronological order inside of a web interface. So I can run something like this:

clj slideshow.clj "/path/to/my/photos"

then visit the directory's url http://localhost:8080/photos (photos being the dirname from above) to see an ordered slideshow of my images with some neat jquery effects. The best part about the jquery is that the images are housed locally, so they should load extra fast, making the effects run smoothly. In fact, rather than a command line argument it could just launch the server with a page that asks for the path of the photos directory.

anyway, that's what i'm going to try before jumping right into an official work project as my first clojure application.


Flickr: jabella's stuff tagged with balloonlaunch

I've noticed that I share more links than anyone. Either that, or none of my friends allow me to see links they've shared in the privacy settings. But it makes me wonder, why would my friends read so many uninteresting things? If it's interesting, share it. Please?


My Desk At Work

Rearranged my desk after getting a new monitor. The one on the right is hooked to a Windows desktop where I do all my stuff that requires windows. The one on the left is hooked up to my MacBook where I do a lot of coding and emails. Everything you see here (besides what's on the shelves) belongs to notifymd. I love my job.

Built a desk at home out of an old door we removed during rennovations to the house. I'll post pictures of that set up when it's done.
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