[Tutor] dynamically creating list

[A.T.Hofkamp]

Bala subramanian wrote:
> 1) Now my question is, how to make this list creation dynamics, say if user
> enter number of clusters = 4, i would create four list. If the user enter 3,
> then i shd create three lists inside my program. How to do this dynamic
> creation of list depending on user input.

Use a list to collect everything, where each value represents data from a cluster.

Each value is a list of data points.

all = []
for n in range(num_clusters):
	all.append([])

for point in data_points:
	cluster = assign_cluster(point)
	all[cluster].append(point)

This would give you something like
[ [ pointA1, pointA2, pointA3, ..., pointAn ],
   [ pointB1, pointB2, pointB3, ..., pointBm ],
   ...
]

where 'pointAx' are points for the first cluster (number 0), 'pointBx' are 
points for the second cluster (number 1), etc.

The list of points for cluster 'num' is then 'all[num]'.

A single point can be accessed as all[2][1] which gives you the second point 
on the third cluster.

(or:

points = all[2]
print points[1]

)



Sincerely,
Albert