vostrus...@gmail.com wrote: > Hi, > I have a file with one parameter per line: > a1 > b1 > c1 > a2 > b2 > c2 > a3 > b3 > c3 > ... > The parameters are lines of characters (not numbers) > > I need to load it to 2D array for further manipulations. > So far I managed to upload this file into 1D array: > > ParametersRaw = []
No need for this assignment as you throw the value away. > with open(file1) as fh: > ParametersRaw = fh.readlines() > fh.close() The with open() ... statement already ensures that the file is closed. > NumberOfColumns = 7 > NumberOfRows = len(ParametersRaw)/NumberOfColumns > > Parameters = [[],[]] > i=0 > j=0 > k=0 > while (i < NumberOfRows): > while (j < NumberOfColumns): > k = (i*NumberOfColumns)+j > Parameters[i][j] = ParametersRaw[k] The inner lists Parameters[i] are empty so every assignment Parameters[i][k] = ... will fail. While the minimal fix is to use append() Parameters[i].append(ParametersRaw[k]) you will run into the same problem with the rows if there are more than the two you prepared for in the line > Parameters = [[],[]] > j = j + 1 > i = i + 1 > j = 0 > > it fails at the line "Parameters[i][j] = ParametersRaw[k]" with error: > > IndexError: index 0 is out of bounds for axis 0 with size 0 > > In case of populating 1D array I would use append() method. > But in case of 2D I am lost of how append() can be applied. > Could some one help newbie. As a general remark in idiomatic Python the loop i = 0 while i < THRESHOLD: ... i = i + 1 is written as a for loop with range(): for i in range(THRESHOLD): ... For your specific problem list slicing is a good approach: COLUMNS = 7 with open(file1) as f: parameters_raw = f.readlines() parameters = [] for row_start in range(0, len(parameters_raw), COLUMNS): parameters.append(parameters_raw[row_start:row_start+COLUMNS]) -- https://mail.python.org/mailman/listinfo/python-list