Python tips

1. change list of strings to list of arrays

   (1) use map(command, list) : apply ‘command’ to all elements of ‘list’

        -> in python 2: map returns list

        -> in python 3: map returns iterator

   (2) use list comprehension: [ ‘cmd’(x) for x in ‘list’]

2. search strings in lists

  (1) return index of matching list elements

   matching= [lines.index(s) for s in lines if "searching" in s]

3. join two arrays as columns

   np.column_stack(array1,array2)

4. multiple arguments as a tuple or unpack tuple

   *(tuple) unpacks the tuple

   **(dictionary) unpacks the dictionary

   it enables

   (1) defined function to receive arbitary number of arguments

         def f(*arguments)

    (2) passing arguments as tuple

         x=(1,2,3)

         f(*x) is equivalent f(1,2,3)