It looks like you’re trying to extend a list with a scalar float variable. The argument to extend must be an iterable (i.e. not a float). From your first bit of code it looks like means[i][j][k] returns a float,
print means['716353'][0][0] #OUT : 76.6818181818
The problem is here,
temp.extend(means[row['ID']][i][0])
If you expect that means[i][j][k] will always be a single value and not a list you can use append instead of extend.
temp.append( means[row['ID']][i][0] )
An example to show the difference,
l = [i for i in range(10)] l.extend( 99.0 ) TypeError: 'float' object is not iterable
this doesn’t work b/c a float is not iterable
l.extend( [99.0] ) print l [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 99.0]
this works b/c a list is iterable (even a one element list)
l.append( 101.0 ) print l [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 99.0, 101.0]
append does work with a non-iterable (e.g. a float)