list index out of range in for loop (2nd iteration)

In my programm I take some data (variable raw) out of a database and have to use it. When using print(raw) this gets displayed: ('x1 y1 z1 nx2 y2 z2 nx3 y3 z3 nx4 y4 z4',) (raw has over 450 elements so I shortened it)

Now I have to get x1 and y1 and forward them to another module. To do this I first split up raw

 pass_str = str(raw).split(f'\n')
 print(pass_str)

The printed result was the following: ["('x1 y1 z1 ", 'x2 y2 z2', 'x3 y3 z3', 'x4 y4 z4',)"]

To get the single parameters I used a for-loop so I can first get x1, y1 and then x2, y2 and so on:

 for i in range(len(pass_str)):
  pass_data = pass_str[i].split()
  el = pass_data[0].split("'", 1)[1]  
  az = pass_data[1]
  task = 'P' + ' ' + az + ' ' + el
  client.send_request(task)

The first iteration of the for-loop works without any problems. In the second iteration the for-loop stops after pass_data = pass_str[i].split()

The problem seems to occure in the line for “el = …”, where I get the error

Error: list index out of range

Answer

You’re trying to use the string representation of a list, then parse that to extract some meaningful data. The string representation of a list is not a very useful data structure to try and work with! Whereas a list itself is.

raw =  [('x1 y1 z1 \nx3 y2 z1',)]
pass_str = str(raw).split(f'\n') # ["[('x1 y1 z1 \", "x3 y2 z1',)]"]

You should be converting the string into a list, and accessing it properly.

raw =  [('x1 y1 z1 \nx3 y2 z1',)]
pass_strings = raw[0][0].split('\n') #["x1 y1 z1","x3 y2 z1"]

for pass_string in pass_strings:
    pass_data = pass_string.split() #['x1','y1','z1']

    el = pass_data[0]
    az = pass_data[1]
    task = 'P' + ' ' + az + ' ' + el
    print(task) #> P x1 y1