How to read specific lines of a file into a 2d array in python -

hello chemistry phd student "attempting" write code in python

i have input file below reading in

item: timestep 20000000 item: number of atoms 2 item: box bounds pp pp pp 0 51.577 0 51.048 1.06653 47.9335 item: atoms id type x y z 5 1 15.6042 48.7947 36.9084 27 1 18.4619 1.23863 36.2611 item: timestep 20005000 item: number of atoms 2 item: box bounds pp pp pp 0 51.577 0 51.048 1.03417 47.9658 item: atoms id type x y z 5 1 16.183 47.8777 37.7161 27 1 17.9296 50.8771 36.5807 ................... 

i want read file , extract point of array have handled far code

in_name = raw_input('name of input: ')     r_file = (open(in_name, 'r')) #readfile  j, line in enumerate(r_file):     if j%11 == 10: 

where getting line starts 27 every time reference.

however can't seem append 1 line multidimensional array.

i want array of floats this

[[27.00], [1.00], [17.9296], [50.8771],[36.5807]] 

when read in data not worrying line reading this

lines = [line.split() line in r_file] 

which convert using

for x in range(length):     y in range(len(lines[x])):         lines[x][y]=float(lines[x][y])    

how can doing line.split() 1 line @ time , append array desired line?

you should create empty list before start looping on lines of file. then, @ each iteration of loop have data (i guess on last line of every 11-line set?), split line components before (.split()). makes more sense convert data floats @ point, in opinion. finally, .append() new line of data list declared @ beginning. gives list of lists of numbers, i.e. 2-dimensional array.

something this:

file_location = # wherever data data = [] open(file_location, 'r') f:     index, line in enumerate(f):         if index % 11 == 10:             data_line = [float(num) num in line.split()]             data.append(data_line) 

now, data looks this:

[[27.0, 1.0, 18.4619, 1.23863, 36.2611],  [27.0, 1.0, 17.9296, 50.8771, 36.5807]] 

additional note: have used with open(...) f: construction. if you're not familiar it, shorthand saves having .close() file when you're done it.