How would you improve this:
time = Time.now
@time = []
@time.push(
(time-1.week).strftime("%m-%d"),
(time-6.days).strftime("%m-%d"),
(time-5.days).strftime("%m-%d"),
(time-4.days).strftime("%m-%d"),
(time-3.days).strftime("%m-%d"),
(time-2.days).strftime("%m-%d"),
(time-1.day).strftime("%m-%d"),
(time).strftime("%m-%d")
)
I'm trying out some of the suggestions below:
time = Time.now
iterations = 1000
Benchmark.bm do |bm|
bm.report do
iterations.times do
@time = 7.downto(0).map { |v| (time - v.days).strftime("%m-%d") }
end
end
bm.report do
iterations.times do
@time = []
@time.push(
(time-1.week).strftime("%m-%d"),
(time-6.days).strftime("%m-%d"),
(time-5.days).strftime("%m-%d"),
(time-4.days).strftime("%m-%d"),
(time-3.days).strftime("%m-%d"),
(time-2.days).strftime("%m-%d"),
(time-1.day).strftime("%m-%d"),
(time).strftime("%m-%d")
)
end
end
end
user system total real
0.350000 0.960000 1.310000 ( 1.310054)
0.310000 0.840000 1.150000 ( 1.156484)
downto is demonstrably slower than my method.
The next test used the method:
@time = (0..7).map { |x| (time - x.days).strftime("%m-%d") }.reverse
1000 iterations
user system total real
0.340000 0.980000 1.320000 ( 1.321518)
0.300000 0.840000 1.140000 ( 1.149759)
5000 iterations
user system total real
1.720000 4.800000 6.520000 ( 6.545335)
1.530000 4.180000 5.710000 ( 5.712035)
I'm having a hard time wrapping my head around this without looking at both downto and map in the Ruby core, but in both cases my more elongated method of writing this responds faster than the more simplified methods (I like the answers below much more from a readability standpoint). Please shed some light on my tests if I'm doing it wrong. I expected map to blow my way out of the water.
UPDATED FOR STEFAN'S ANSWER
So I see Stefan's answer below and throw it in the tester:
user system total real
0.040000 0.000000 0.040000 ( 0.035976)
1.520000 4.180000 5.700000 ( 5.704401)
Holy crap! 5000 iterations and it absolutely destroys my method.
Because he accurately points out that I'm only interested in Dates, I decide to change my own method from Time.now to Date.today and test it:
user system total real
0.090000 0.000000 0.090000 ( 0.085940)
0.390000 0.000000 0.390000 ( 0.398143)
It's somewhat weird that in the first test Stefan's method clocks in at 0.0359 and in the second clocks at 0.0859, more than double, but it's still hundredths of a second over 5000 iterations - so I think I'm deep into splitting hairs territory here.
Nevertheless - Stefan's way obliterates my own method - so I'm giving him the check mark.
You can do as below using #downto
-
time = Time.now
@time = 7.downto(0).map {|v| (time - v.days).strftime("%m-%d") }
You can use not pushing itself, but collection, ie combination of Range
from zero to seven, and Array
's #map
method:
time = Time.now
@time = (0..7).map {|v| (time - v.days).strftime("%m-%d") }.reverse
# => ["04-24", "04-25", "04-26", "04-27", "04-28", "04-29", "04-30", "05-01"]
I would write it using the Array#map
method
time = Time.now
@time = (0..7).map { |x| (time - x.days).strftime("%m-%d") }.reverse
Since you're only interested in dates, you could use a Range
of Date
instances (dates increment in 1-day steps ):
today = Date.today
(today-7..today).map { |date| date.strftime("%m-%d") }
#=> ["04-24", "04-25", "04-26", "04-27", "04-28", "04-29", "04-30", "05-01"]
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