Question

Part of my python script:
(I first made the dictionary “h”)

def histogram(L):
    d= {}
    for x in L:
       if x in d:
          d[x] +=1
       else:
          d[x] =1
    return d
h=histogram(LIST)

for vhfile in vhfiles:
    linelist=commands.getoutput('cat ' + vhfile).splitlines(True)
    list1=[]
    for line in linelist:
        name1 = line.split()[0]
        if int(h[name1]) <= 300:
           list1.append(line)

Then I got error at “if” line:

File "/home/xug/scratch/mrfast/NA12878/dis_rm.py", line 51, in <module>
    if int(h[name1]) <= 300:
KeyError: '080821_HWI-EAS301_0002_30ALBAAXX:1:46:1643:1310'

Any idea what happened here?
thx

Answer 1

You get a KeyError when you try to look something up in the dict, and the dict doesn’t contain that key.

In this case, it appears that the key '080821_HWI-EAS301_0002_30ALBAAXX:1:46:1643:1310' does not occur in h.