error due to version

[hknarahari]

I found this python code to read data and create GMSH .geo file. However, when I use it i get an error

# script to create a .geo file for a multi element airfoil
# Read the coordinates to two lists
mainCoords = []
flapCoords = []
with open('gaw.txt') as fin:
    fin.readline() # skip header
    fin.readline() # skip header
    for l in fin:
        coords = map(float,l.split())
        print('coords')
        mainCoords.append(coords[:2])
        if len(coords) > 2:
            flapCoords.append(coords[2:])

# Create a GMSH file and write the points in GMSH format
with open('multi.geo','w') as fout:
    for i, c in enumerate(mainCoords):
        fout.write('Point (%i) = {%f, %f, 0, 1};\n'%(i+1,c[0],c[1]))
    for i, c in enumerate(flapCoords):
        fout.write('Point (%i) = {%f, %f, 0, 1};\n'%(i+len(mainCoords)+1,c[0],c[1]))

# Create two splines 
    fout.write('Spline (1) = {%s};\n' % ','.join(map(str,range(1,len(mainCoords)+1))))
    fout.write('Spline (2) = {%s};\n' % ','.join(map(str,range(len(mainCoords)+1,len(mainCoords)+len(flapCoords)+1))))

I get the following error :

Error:
runfile('D:/AERO_AUTO/CFD_HKN/gmsh-4.3.0-Windows64/hkn/Multi_element.py', wdir='D:/AERO_AUTO/CFD_HKN/gmsh-4.3.0-Windows64/hkn')
coords
Traceback (most recent call last):

  File "<ipython-input-5-d8984351fb2d>", line 1, in <module>
    runfile('D:/AERO_AUTO/CFD_HKN/gmsh-4.3.0-Windows64/hkn/Multi_element.py', wdir='D:/AERO_AUTO/CFD_HKN/gmsh-4.3.0-Windows64/hkn')

  File "E:\aconda\lib\site-packages\spyder_kernels\customize\spydercustomize.py", line 704, in runfile
    execfile(filename, namespace)

  File "E:\aconda\lib\site-packages\spyder_kernels\customize\spydercustomize.py", line 108, in execfile
    exec(compile(f.read(), filename, 'exec'), namespace)

  File "D:/AERO_AUTO/CFD_HKN/gmsh-4.3.0-Windows64/hkn/Multi_element.py", line 11, in <module>
    mainCoords.append(coords[:2])

TypeError: 'map' object is not subscriptable

I think the error is due to python version (i use 3., but not sure Any help will be greatly helpful.
Thanks
Narahari

[buran]

you are right
the simplest solution is

        coords = list(map(float,l.split()))

another option

coords = [float(n) for n in l.split()]

also you can always use 2to3 tool to auto convert the script to py3

[ndc85430]

You can't slice a map object (i.e. coords[:2]) because it's not a normal sequence, but basically a generator. If you really want to do that, then you'll need to consume that generator (i.e. go through it and get all the items). You can do that by passing it to, say, the list function that will create a list from the items:

>>> l1 = [1, 2, 3]                                                                                       
>>> m = map(lambda x: x * 2, l1)  
>>> m
<map object at 0x7ff814caac50>                                                                                          
>>> l2 = list(m)
>>> l2
[2, 4, 6]
>>>