Grabbing just the content of a line

Question

I have a simple question: I want to just grab the content of a line from a file x. My file x looks like this:

PointXY
[387.93852, 200.0]
PointXY
[200.0, 387.93852]
PointXY
[200.0, 387.93852]
PointXY
[200.0, 353.20889]
PointXY
[387.93852, 200.0]
PointXY
[200.0, 387.93852]
PointXY
[200.0, 300.0]

My script in Python looks like this:

h = open("x.gcode", "r")
searchlines = h.readlines()
file = ""

for i, line in enumerate(searchlines):
    if "PointXY" in line:
        P = searchlines[i+1]
        print(P)

I want P to just be [200.0, 100.0] (for instance). It now gives me '[200.0, 100.0]\n'. How can I adjust this in the line "P = searchlines[i+1]"?

So you are looking to have it without the '\n'? – idjaw Apr 03 '16 at 14:53 — idjaw, Apr 03 '16 at 14:53

score 2 · Answer 1 · answered Apr 03 '16 at 14:55

2

You can use str.strip() to remove the \n

for i, line in enumerate(searchlines):
    if "PointXY" in line:
        P = searchlines[i+1].strip()
        print(P)

answered Apr 03 '16 at 14:55

KIDJourney

1,200
1
9
22

Thanks, that god rid of the \n, how do I get rid of the ' '? I want P to be [200.0, 100.0], now it stills returns '[200.0, 100.0]'. – Henry Apr 03 '16 at 15:09
@Henry You use json.loads. Check my answer. – idjaw Apr 03 '16 at 15:11
@Henry You can use `json.loads` in @idjaw 's answer or us `re` to match the number you want . – KIDJourney Apr 03 '16 at 15:14

idjaw · Accepted Answer · 2016-04-03T15:10:52.723

2

You are looking to strip the new line character from each line, which you can easily do using the available strip method of str:

When you get your data in searchlines, do:

searchlines[i+1].strip()

To see that it is actually removed, check the repr:

 print(repr(P))

You can even do that repr print before and after applying the strip() to see what happened when calling that strip.

Considering the structure of the text you have, you are looking to make it a list, so, you could use loads from json to do this:

json.loads(searchlines[i+1].strip())

edited Apr 03 '16 at 15:10

answered Apr 03 '16 at 14:56

idjaw

25,487
7
64
83

Thanks, that god rid of the \n, how do I get rid of the ' '? I want P to be [200.0, 100.0], now it stills returns '[200.0, 100.0]'. – Henry Apr 03 '16 at 15:11
@Henry My answer has been updated to include that already. Check the last line. – idjaw Apr 03 '16 at 15:11

Milor123 · Answer 3 · 2016-04-03T15:52:22.110

0

if you want delete '\n' use this

after read data

data = f.readlines()

data = map(str.strip, data)

but isn't necessary for the other you could use this:

import ast
listdata = []
with open('lel.txt') as f:
    data = f.readlines()
    for x in data:
        try:
            if isinstance(ast.literal_eval(x), list):
                listdata.append(eval(x))
        except:
            pass

then for get data of list:

print listdata
>>>[[387.93852, 200.0], [200.0, 387.93852], [200.0, 387.93852], [200.0, 353.20889], [387.93852, 200.0], [200.0, 387.93852], [200.0, 300.0]]
print listdata[0]
>>>[387.93852, 200.0]
print listdata [0][0]
>>>387.93852

edited Apr 03 '16 at 15:52

answered Apr 03 '16 at 15:22

Milor123

537
4
20

Using `eval` should not be used as a suggested answer, and should not be used in general. – idjaw Apr 03 '16 at 15:38
Sure. Best to read [this](http://stackoverflow.com/a/1832957/1832539) . Look up "why is eval bad practice in python". Actually in many languages you will find reasons not to use eval. – idjaw Apr 03 '16 at 16:34
@idjaw Thanks you :3, I've Changed by a small alternative which is ast.literal_eval(). Greetings! – Milor123 Apr 03 '16 at 17:27
You're very welcome. `literal_eval` is an appropriate approach. Good stuff. – idjaw Apr 03 '16 at 17:27

Grabbing just the content of a line

3 Answers3