Introduction¶
Having recently added the dump command to BlogMore I've been thinking I should try and learn a little more about jq. It's one of those tools that's been on my radar for ages, which I've used on very rare occasions to get something done quickly, but which I've never really used in anger.
So I thought it might be fun to see about recreating some of the stats from the stats page using jq alone. Well, I say "alone", I mean "from the JSON data that is produced by the BlogMore dump command", and of course that makes it easier given it dumps some of the key calculated values. In other words I won't be using jq to calculate the word count, or reading time, or GFI, etc.
Post count¶
To start with, working out the number of posts in my blog is simple enough:
Category count¶
Getting the list of categories would be:
jq '[.[] .safe_category] | unique'
[
"ai",
"coding",
"creative",
"emacs",
"gaming",
"life",
"meta",
"music",
"python",
"tech",
"til"
]
and so getting the count of them is simple enough:
jq '[.[] .safe_category] | unique | length'
Getting the count of tags takes a little more work, as safe_tags is a list too, so I start out with a list of lists, which I need to flatten first.
jq '[.[] .safe_tags] | flatten | unique | length'
This, right away, is an interesting finding. In my stats page, as of the time of writing, the number of tags is reported as 243, but here I'm getting 224. Given I'm using the safe_tags property, which ensures all similar tags end up with the same value (so Hello World, hello world, and all variations, become hello-world), that would suggest the stats page isn't taking that into account. That's an issue to address.
A date/time interlude¶
Here's where things get a little interesting for a moment. In the output of the dump command from BlogMore, the dates of the posts are given in ISO 8601 format; specifically the date and time with offset format. From what I can tell, while jq does have some date/time parsing support, it can't handle that format specifically.
This means that if I try:
jq '.[0] .date | fromdate'
I just get:
jq: error (at <stdin>:27293): date "2015-06-18T14:53:00+01:00" does not match format "%Y-%m-%dT%H:%M:%SZ"
After some searching around it seems the only approach I can really take is to drop the timezone offset and pretend every time is a Z time:
jq '.[0] .date[:19] + "Z" | fromdate'
From here I can then get a fully-parsed list of date/time values using gmtime:
jq '.[0] .date[:19] + "Z" | fromdate | gmtime'
[
2015,
5,
18,
14,
53,
0,
4,
168
]
This isn't ideal for what I'd like to do, it's going to skew some of the values related to time, but it's close enough for experimenting.
Posts per year¶
Now that I have a way of breaking the posting time into a workable array of values, getting the number of posts per year becomes:
jq -r '[.[] .date[:19] + "Z" | fromdate | gmtime[0]] | group_by(.) | .[] | "\(.[0]): \(length)"'
2015: 32
2016: 26
2017: 7
2018: 1
2019: 15
2020: 23
2022: 11
2023: 49
2024: 19
2025: 11
2026: 177
Although, to be fair to jq, that's kind of long-winded when I could just pull the year itself out of the posting time:
jq -r '[.[] .date[:4]] | group_by(.) | .[] | "\(.[0]): \(length)"'
Posts by month¶
At this point getting the posts by month of year seems obvious too:
jq -r '[.[] .date[5:7]] | group_by(.) | .[] | "\(.[0]): \(length)"'
01: 14
02: 12
03: 53
04: 57
05: 76
06: 33
07: 25
08: 25
09: 13
10: 29
11: 19
12: 15
Posts by weekday¶
For this, I need to go back to the more involved version of the posting date handling query, where I use gmtime to break down the time. It turns out that the penultimate value is the day of the week as a number. So, while it's not quite as readable in that I don't have day names, I can get the values:
jq -r '[.[] .date[:19] + "Z" | fromdate | gmtime[-2]] | group_by(.) | .[] | "\(.[0]): \(length)"'
0: 48
1: 54
2: 51
3: 48
4: 56
5: 56
6: 58
In this case Sunday is the first day (the 0 day here).
Posts by hour¶
Getting the posts by the hour is really just a variation on the date-chopping query used for the posts by year and the posts by month; it's all there in the string version of the date.
jq -r '[.[] .date[11:13]] | group_by(.) | .[] | "\(.[0]): \(length)"'
00: 1
06: 1
07: 6
08: 51
09: 35
10: 32
11: 25
12: 14
13: 22
14: 24
15: 25
16: 24
17: 18
18: 9
19: 23
20: 33
21: 21
22: 6
23: 1
First and last posting dates¶
Getting the date of the first and latest post seems nice and easy:
jq -r '[.[] .date[0:10]] | {first: min, last: max}'
{
"first": "2015-06-18",
"last": "2026-06-01"
}
Although, from what I can tell, jq doesn't have anything that makes date arithmetic easy so working out the elapsed time between the two isn't so straightforward. It can be done, but it's not as easy as it might be with a bit of Python code, for example. The best I could come up with was:
jq '[ .[] | .date[:19] + "Z" | fromdate ] | ((max - min) / (365.25 * 24 * 60 * 60))'
For an approximate value of "year", of course.
Word counts¶
From here on in many of the stats that can be pulled out from the JSON, with jq, become easier to handle. Each post has a word_count property, so I only need to do this:
jq -r '[.[] .word_count] | {least: min, most: max, average: (add / length)}'
{
"least": 24,
"most": 2792,
"average": 475.0700808625337
}
Reading times¶
A post's reading time can be accessed by reading_time, so it's as easy to handle as the word counts:
jq '[.[] .reading_time] | {least: min, most: max, average: (add / length)}'
{
"least": 1,
"most": 11,
"average": 1.8921832884097034
}
Gunning fog index¶
The Gunning fog index is available as the gfi property so there's no work to do to figure it out. It is, however, a floating point value and I want counts in each integer "bucket". That can be done with round.
jq -r '[.[] .gfi | round] | group_by(.) | .[] | "\(.[0]): \(length)"'
3: 1
4: 2
5: 3
6: 7
7: 30
8: 46
9: 67
10: 70
11: 75
12: 35
13: 18
14: 11
15: 1
16: 3
17: 2
As for working out the mean, median and mode... while I worked out the above queries by reading the docs, experimenting, and using Gemini on occasion to either help me understand an error message or to explain why an approach works the way it did, I'm going to have to leave this one 100% to Gemini. Here's its approach to using jq to work out those averages:
jq '
[ .[] | .gfi | select(. != null) ] as $raw_gfi
| [ $raw_gfi[] | round ] as $rounded_gfi
| ($raw_gfi | length) as $count
# 1. Mean Calculation
| (($raw_gfi | add) / $count) as $mean
# 2. Median Calculation
| ($raw_gfi | sort) as $sorted_gfi
| (if $count % 2 == 1 then
$sorted_gfi[($count - 1) / 2]
else
($sorted_gfi[($count / 2) - 1] + $sorted_gfi[$count / 2]) / 2
end) as $median
# 3. Mode Calculation (using the rounded values)
| [ $rounded_gfi
| group_by(.)
| map({gfi: .[0], frequency: length})
| sort_by(.frequency)
| reverse
| .[]
] as $frequencies
| [ $frequencies[] | select(.frequency == $frequencies[0].frequency) | .gfi ] as $modes
# Final Object Assembly
| {
count: $count,
mean: $mean,
median: $median,
mode: $modes
}
'
{
"count": 371,
"mean": 9.908842231503396,
"median": 9.979198312236287,
"mode": [
11
]
}
As of the time of writing: that's bang on what I get in the stats. Honestly though, by this point, I think I'd be reaching for Python or something similar to do this sort of work. For sure, I can't say if this is a good jq query, if it's in any way idiomatic, or even if it's error-free. The numbers match what BlogMore says though.
Conclusion¶
This has been a useful exercise in getting to know a little more about jq, and I can see myself reaching for it to do quick little jobs now that I've finally taken some time to dive into it. As it turns out, it's also been a useful little audit of the content of the stats page because I've even found a bug that needs addressing; so that's a bonus.
