I have a problem that is simple but I am not getting the solution.
I have a list of tuples, for example:
lista = [('x',2,3),('y',4,5),('x',6,7),('z',8,9)]
What I want is for him to tell me how many times x , y and z appear in this list. In this case, x appears 2 times and y and z appear 1 , so should return a list with [2,1,1] .
And I wanted to resolve this with map or reduce .
You can use the excellent Counter of collections :
from collections import Counter
lista_contagens = Counter(map(lambda: x, x[0], lista))
# Isto imprime as contagens
print(lista_contagens.values())
Word count is the basic example of map / reduce. For this case, just adapt to the map stage and implement the traditional reduce. Here is an example for mapper:
mapper.py
lista = [('x',2,3),('y',4,5),('x',6,7),('z',8,9)]
for i in lista:
print '%s\t%s' % (i[0], '1')
Following is a complete sample documentation: link