--> Dictionaries are used to store data values in key:value pairs.
--> A dictionary is a collection which is ordered, changeable and do not allow duplicates.
-->In dictionary each element can be accessed by their keys, not through indexing.
-->If dictionary does not contain the key then the output will be 'KeyError'.
Example:
thisdict = { "brand": "Ford", "model": "Mustang", "year": 1964 } student = {"name":"raja", "class":5} print(thisdict) print(student)
Output:
{'brand': 'Ford', 'model': 'Mustang', 'year': 1964} {'name': 'raja', 'class': 5}
Exercises:Find characters in a string using Nested loops
1. Finding frequency of each letter in a string
s = 'guruprasanna' name = list(s) j = 0 while j<len(name): key = name[j] count = 1 i = j+1 if key != '*': while i<len(name): if key == name[i]: name[i] = '*' count+=1 i+=1 print(key, count) j+=1
Output:
g 1 u 2 r 2 p 1 a 3 s 1 n 2
*2. Letters appeared Only Once *
s = 'guruprasanna' name = list(s) j = 0 while j<len(name): key = name[j] count = 1 i = j+1 if key != '*': while i<len(name): if key == name[i]: name[i] = '*' count+=1 i+=1 if count == 1 and key!='*': print(key, count) j+=1
Output:
g 1 p 1 s 1
3. Most frequent letter
s = 'guruprasanna' name = list(s) j = 0 while j<len(name): key = name[j] count = 1 i = j+1 if key != '*': while i<len(name): if key == name[i]: name[i] = '*' count+=1 i+=1 if count != 1 and key!='*': print(key, count) j+=1
Output:
u 2 r 2 a 3 n 2
4. First Non-repeated letter
s = 'guruprasanna' name = list(s) j = 0 while j<len(name): key = name[j] count = 1 i = j+1 if key != '*': while i<len(name): if key == name[i]: name[i] = '*' count+=1 i+=1 if count == 1 and key!='*': print(key, count) break j+=1
Output:
g 1
5. First repeated letter
s = 'guruprasanna' name = list(s) j = 0 while j<len(name): key = name[j] count = 1 i = j+1 if key != '*': while i<len(name): if key == name[i]: name[i] = '*' count+=1 i+=1 if count != 1 and key!='*': print(key, count) break j+=1
6. Last non-repeated letter
last = ' ' last_count = 0 s = 'guruprasanna' name = list(s) j = 0 while j<len(name): key = name[j] count = 1 i = j+1 if key != '*': while i<len(name): if key == name[i]: name[i] = '*' count+=1 i+=1 if count == 1 and key!='*': last = key last_count = count #print(key, count) j+=1 print(last, last_count)
Output:
s 1
7. Last repeated letter
last = ' ' last_count = 0 s = 'guruprasanna' name = list(s) j = 0 while j<len(name): key = name[j] count = 1 i = j+1 if key != '*': while i<len(name): if key == name[i]: name[i] = '*' count+=1 i+=1 if count != 1 and key!='*': last = key last_count = count #print(key, count) j+=1 print(last, last_count)
Output:
n 2
8. Most Frequent letter
s = 'guruprasanna' name = list(s) j = 0 last = ' ' last_count = 0 while j<len(name): key = name[j] count = 1 i = j+1 if key != '*': while i<len(name): if key == name[i]: name[i] = '*' count+=1 i+=1 if count != 1 and key!='*': if count>last_count: last = key last_count = count j+=1 print(last, last_count)
9. Frequency of Vowels (a,e,i,o,u)
vowels = ['a','e','i','o','u'] last = ' ' last_count = 0 s = 'guruprasanna' name = list(s) j = 0 while j<len(name): key = name[j] if key in vowels: count = 1 i = j+1 if key != '*': while i<len(name): if key == name[i]: name[i] = '*' count+=1 i+=1 if key!='*': print(key, count) j+=1
Output:
u 2 a 3
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