old_contents: from __future__ import division
  
  """
  Script to wrap around nosetests to only run on files modified in the past 10
  commits as well as 10% of all files.
  """
  
  import os
  import sys
  import subprocess
  import random
  import time
  import multiprocessing
  
  
  run_ratio = 1/10
  
  try:
      files_changed = []
      for parent, sub, files in os.walk("pymatgen"):
          for f in files:
              if f.endswith(".py"):
                  p = os.path.join(parent, f)
                  statbuf = os.stat(p)
                  if time.time() - statbuf.st_mtime < 60 * 60 * 24 * 10:
                      files_changed.append(p)
  
              # output = subprocess.check_output(["git", "diff", "--name-only", "HEAD~20"])
              # files_changed = [f for f in output.decode("utf-8").split("\n")
              #                  if f.startswith("pymatgen")]
  except subprocess.CalledProcessError:
      print("Can't get changed_files... Setting run_ratio to 100%")
      run_ratio = 1
      files_changed = []
  
  
  must_run = []
  for f in files_changed:
      d = os.path.dirname(f)
      b = os.path.basename(f)
      testname = os.path.join(d, "tests", "test_" + b)
      if os.path.exists(testname):
          must_run.append(testname)
  
  can_run = []
  for parent, subdir, files in os.walk("pymatgen"):
      for f in files:
          if (parent.endswith("tests") and f.startswith("test_")
                  and f.endswith(".py") and f not in must_run):
              can_run.append(os.path.join(parent, f))
  
  print("%d test files must be run..." % len(must_run))
  print(must_run)
  print("%d possible test files can be run..." % len(can_run))
  
  nrun = int(run_ratio * len(can_run))
  
  if random.randint(1, 20) % 20 == 0:
      # One in fifty times, we will run a full test.
      to_run = must_run + can_run
  else:
      to_run = list(set(random.sample(can_run, nrun) + must_run))
  
  
  print("%d test files will be run..." % len(to_run))
  statuses = []
  
  def run_test(f):
      print("Running %s" % f)
      return subprocess.call(["python", f])
  
  ncpus = multiprocessing.cpu_count()
  print("Using %d cpus" % ncpus)
  p = multiprocessing.Pool(ncpus)
  results = p.map(run_test, to_run[0:4])
  if any(results):
      sys.exit(-1)
  else:
      sys.exit(0)
  
  
new_contents: from __future__ import division
  
  """
  Script to wrap around nosetests to only run on files modified in the past 10
  commits as well as 10% of all files.
  """
  
  import os
  import sys
  import subprocess
  import random
  import time
  import multiprocessing
  
  
  run_ratio = 1/10
  
  try:
      files_changed = []
      for parent, sub, files in os.walk("pymatgen"):
          for f in files:
              if f.endswith(".py"):
                  p = os.path.join(parent, f)
                  statbuf = os.stat(p)
                  if time.time() - statbuf.st_mtime < 60 * 60 * 24 * 10:
                      files_changed.append(p)
  
              # output = subprocess.check_output(["git", "diff", "--name-only", "HEAD~20"])
              # files_changed = [f for f in output.decode("utf-8").split("\n")
              #                  if f.startswith("pymatgen")]
  except subprocess.CalledProcessError:
      print("Can't get changed_files... Setting run_ratio to 100%")
      run_ratio = 1
      files_changed = []
  
  
  must_run = []
  for f in files_changed:
      d = os.path.dirname(f)
      b = os.path.basename(f)
      testname = os.path.join(d, "tests", "test_" + b)
      if os.path.exists(testname):
          must_run.append(testname)
  
  can_run = []
  for parent, subdir, files in os.walk("pymatgen"):
      for f in files:
          if (parent.endswith("tests") and f.startswith("test_")
                  and f.endswith(".py") and f not in must_run):
              can_run.append(os.path.join(parent, f))
  
  print("%d test files must be run..." % len(must_run))
  print(must_run)
  print("%d possible test files can be run..." % len(can_run))
  
  nrun = int(run_ratio * len(can_run))
  
  if random.randint(1, 20) % 20 == 0:
      # One in fifty times, we will run a full test.
      to_run = must_run + can_run
  else:
      to_run = list(set(random.sample(can_run, nrun) + must_run))
  
  
  print("%d test files will be run..." % len(to_run))
  statuses = []
  
  def run_test(f):
      print("Running %s" % f)
      return subprocess.call(["python", f])
  
  ncpus = multiprocessing.cpu_count()
  print("Using %d cpus" % ncpus)
  p = multiprocessing.Pool(ncpus)
  results = p.map(run_test, to_run)
  if any(results):
      sys.exit(-1)
  else:
      sys.exit(0)
  
  
subject: Fix mistake in run_circle.