A common use of dictionaries is to count the occurrences of like items in a sequence; a typical example is counting the occurrences of words in a body of text. The following code creates a dictionary where each word in the text is used as a key and the number of occurrences as its value. This uses a very common idiom of nested loops. Here we are using it to traverse the lines in a file in an outer loop and the keys of a dictionary on the inner loop:
def wordcount(fname):
try:
fhand=open(fname)
except:
print('File can not be opened')
exit()
count=dict()
for line in fhand:
words=line.split()
for word in words:
if word not in count:
count[word]=1
else:
count[word]+=1
return(count)
This will return a dictionary with an element for...