% in label causes ArgumentError

[paddor]

I just wanted to use a % sign in the labels of my benchmarks, then I saw this:

Calculating -------------------------------------
/Users/paddor/.gem/ruby/2.1.3/gems/benchmark-ips-2.0.0/lib/benchmark/ips/job.rb:154:in `printf': malformed format string - %) (ArgumentError)
    from /Users/paddor/.gem/ruby/2.1.3/gems/benchmark-ips-2.0.0/lib/benchmark/ips/job.rb:154:in `block in run_warmup'
    from /Users/paddor/.gem/ruby/2.1.3/gems/benchmark-ips-2.0.0/lib/benchmark/ips/job.rb:150:in `each'
    from /Users/paddor/.gem/ruby/2.1.3/gems/benchmark-ips-2.0.0/lib/benchmark/ips/job.rb:150:in `run_warmup'
    from /Users/paddor/.gem/ruby/2.1.3/gems/benchmark-ips-2.0.0/lib/benchmark/ips.rb:37:in `ips'
    from compression_benchmark.rb:15:in `<main>'

Using %% instead is a workaround in the calculation round, but in the second round (the results round), I'll see %% in the output.

I know it's not very common, but I was benchmarking some different compression algorithms for a project and also wanted to include the compression ratio in the benchmark report. :)

[JuanitoFatas]

Hello. Could you show your benchmark code?

[paddor]

Yeah sure. Here you go: https://gist.github.com/paddor/444682b037ac027d061b

[JuanitoFatas]

Thank you. Let me simplify the file to reproduce:

require 'benchmark/ips'

def to_percentage(num)
  "(%i%%)" % num
end

Benchmark.ips do |x|
  x.report("Test 1: #{to_percentage rand(0..100)}") {  }
  x.report("Test 2: #{to_percentage rand(0..100)}") {  }
  x.compare!
end

output

ruby compression_benchmark_github_issue.rb
Calculating -------------------------------------
/Users/Juan/.gem/ruby/2.2.0/gems/benchmark-ips-2.0.0/lib/benchmark/ips/job.rb:154:in `printf': malformed format string - %) (ArgumentError)
    from /Users/Juan/.gem/ruby/2.2.0/gems/benchmark-ips-2.0.0/lib/benchmark/ips/job.rb:154:in `block in run_warmup'
    from /Users/Juan/.gem/ruby/2.2.0/gems/benchmark-ips-2.0.0/lib/benchmark/ips/job.rb:150:in `each'
    from /Users/Juan/.gem/ruby/2.2.0/gems/benchmark-ips-2.0.0/lib/benchmark/ips/job.rb:150:in `run_warmup'
    from /Users/Juan/.gem/ruby/2.2.0/gems/benchmark-ips-2.0.0/lib/benchmark/ips.rb:37:in `ips'
    from compression_benchmark_github_issue.rb:7:in `<main>'

---

require 'benchmark/ips'

def to_percentage(num)
  "(%i%%%%)" % num
end

Benchmark.ips do |x|
  x.report("Test: #{to_percentage rand(0..100)}") {  }
end

output:

ruby compression_benchmark_github_issue.rb
Calculating -------------------------------------
      Test 1: (76%)    162693 i/100ms
      Test 2: (78%)    163378 i/100ms
-------------------------------------------------
      Test 1: (76%%) 11643580.4 (±7.1%) i/s -   57918708 in   5.004459s
      Test 2: (78%%) 11438905.1 (±7.8%) i/s -   56855544 in   5.008368s

Comparison:
      Test 1: (76%%): 11643580.4 i/s
      Test 2: (78%%): 11438905.1 i/s - 1.02x slower