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7
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1 '''
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2 simulate a random interval set that mimics the size and strand of a reference set
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3 '''
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4
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5 def inferSizeFromRefBed(filename,header):
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6 '''
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7 read reference interval set, get chrom size information
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8 '''
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9 chrSize = {}
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10 f = open(filename)
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11 if header:
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12 header = f.readline()
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13 for line in f:
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14 flds = line.strip().split('\t')
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15 if not chrSize.has_key(flds[0]):
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16 chrSize[flds[0]] = int(flds[2])
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17 elif chrSize[flds[0]] < int(flds[2]):
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18 chrSize[flds[0]] = int(flds[2])
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19 f.close()
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20 return chrSize
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21
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22 def getChrSize(filename):
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23 chrSize = {}
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24 f = open(filename)
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25 for line in f:
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26 flds = line.strip().split('\t')
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27 if len(flds) >1:
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28 chrSize[flds[0]] = int(flds[1])
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29 f.close()
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30 return chrSize
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31
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32 def makeWeightedChrom(chrSize):
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33 '''
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34 make a list of chr_id, the freq is proportional to its length
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35 '''
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36
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37 genome_len = 0
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38
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39 for chrom in chrSize:
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40 chrom_len = chrSize[chrom]
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41 genome_len += chrom_len
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42
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43 weighted_chrom = []
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44 for chrom in chrSize:
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45 weight = int(round(1000*float(chrSize[chrom])/genome_len))
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46 weighted_chrom += [chrom]*weight
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47
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48 return weighted_chrom
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49
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50 def randomIntervalWithinChrom(infile,outfile,chrSize,header):
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51 '''
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52 '''
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53 fin = open(infile)
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54 if header:
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55 header = fin.readline()
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56 fout = open(outfile,'w')
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57 n = 0
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58 for line in fin:
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59 n = n + 1
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60 flds = line.strip().split('\t')
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61 interval_size = int(flds[2]) - int(flds[1])
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62 rstart = random.randint(0,chrSize[flds[0]]-interval_size)
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63 fout.write(flds[0]+'\t'+str(rstart)+'\t'+str(rstart+interval_size)+'\t'+str(n)+'\t0\t+\n')
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64 fin.close()
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65 fout.close()
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66
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67 def randomIntervalAcrossChrom(infile,outfile,chrSize,weighted_chrom,header):
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68 '''
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69 '''
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70 fin = open(infile)
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71 if header:
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72 header = fin.readline()
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73 fout = open(outfile,'w')
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74 n = 0
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75 for line in fin:
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76 n = n + 1
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77 flds = line.strip().split('\t')
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78 interval_size = int(flds[2]) - int(flds[1])
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79 # find a random chrom
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80 flds[0] = weighted_chrom[random.randint(0, len(weighted_chrom) - 1)]
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81 # random start in the chrom
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82 rstart = random.randint(0,chrSize[flds[0]]-interval_size)
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83 fout.write(flds[0]+'\t'+str(rstart)+'\t'+str(rstart+interval_size)+'\t'+str(n)+'\t0\t+\n')
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84 fin.close()
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85 fout.close()
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86
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87 import sys,random
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88 def main():
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89 # python random_interval.py test100.bed testout.bed across header human.hg18.genome
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90
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91 reference_interval_file = sys.argv[1]
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92 output_file = sys.argv[2]
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93 across_or_within_chrom = sys.argv[3] # within or across
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94 if sys.argv[4] == 'header':
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95 header = True
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96 else:
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97 header = False
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98 if len(sys.argv) == 6:
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99 chrom_size_file = sys.argv[5]
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100 chrSize = getChrSize(chrom_size_file)
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101 else:
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102 chrSize = inferSizeFromRefBed(reference_interval_file,header)
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103 if across_or_within_chrom == 'within':
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104 randomIntervalWithinChrom(reference_interval_file,output_file,chrSize,header)
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105 else:
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106 randomIntervalAcrossChrom(reference_interval_file,output_file,chrSize,makeWeightedChrom(chrSize),header)
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107 main()
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