从文本文件中的数据将度-分钟转换为弧度

Question

For example in my text file, Data.txt :

AB     N05-30-00E      495.85        
BC     N46-02-00E      850.62       
CD     S67-38-00E      855.45       
DE     S12-25-00E     1020.87      
EF     S83-44-00W     1117.26     
FA     N55-09-00W      660.08

These are the sides, bearing and the length/distance respectively. How can I convert this to radians? (after that I will get the latitude and departures, but I will do that later if only I could get this one first) Then I write a txt file with the results, the fourth and fifth are the latitude and departure.

import math

fileread = open("Data.txt","r")
data = fileread.read
#missing code, convert the string to degrees decimal?
print "%.3f" %  math.cos(math.radians())

Answer 1

I'm not sure I understand what your data presents, so this is just a rough hint at the string conversion part:

# s = "05-30-00"
(degrees, minutes, seconds) = \
   map(float, re.match("(\d+)-(\d+)-(\d+)", s).groups())

Once you've got degrees , minutes , and seconds , you "flatten" them into a single value:

degrees = degrees + minutes / 60.0 + seconds / 3600.0

finally,

rads = math.radians(degrees)

will finish that conversion, as you hinted.

Depending on what you're doing with it, you might want to flip the sign, based on the compass direction, like:

if compass in ('W', 'S'):
  degrees = -degrees

For more details on the conversions, lookup " Geographic coordinate conversion ".

Answer 2

Yes Jay Kominek is right.

Just add to his answer.

1. Created function according Jay Kominek answer.
2. Read input file by CSV modules because file is well structured.
3. Calculate output and write Row in to output file.

input :

AB  N05-30-00E  495.85
BC  N46-02-00E  850.62
CD  S67-38-00E  855.45
DE  S12-25-00E  1020.87
EF  S83-44-00W  1117.26
FA  N55-09-00W  660.08

Demo :

import csv
import math
import re


def convertRedis(format_input):
    """
        Coordinate format conversion
    degrees minutes seconds: 
    decimal degrees = degrees + minutes}/60 + seconds/3600. 
    """
    degrees, minutes, seconds = map(float, re.match("\w(\d+)-(\d+)-(\d+)\w", format_input).groups())
    degrees = degrees + minutes/60 + seconds/3600
    return math.radians(degrees)


with open("Technical Description.txt") as fp:
    root_r = csv.reader(fp)
    root_r = csv.reader(fp, delimiter='\t')
    with open("output.txt", "wb+") as fp2:
        root_w = csv.writer(fp2, delimiter='\t')
        for row in root_r:
            rads = convertRedis(row[1])
            new_row = list(row)
            distance = float(row[2])
            if "S" in row[1]:
                d_cos =  "%.2f"%(distance*math.cos(rads) * -1, )
            else:
                d_cos =  "%.2f"%(distance*math.cos(rads), )

            if "W" in row[1]:
                d_sin =  "%.2f"%(distance*math.sin(rads) * -1, )
            else:
                d_sin =  "%.2f"%(distance*math.sin(rads), )

            new_row.extend([d_sin, d_cos])
            root_w.writerow(new_row)

Output:

AB  N05-30-00E  495.85  47.53   493.57
BC  N46-02-00E  850.62  612.23  590.53
CD  S67-38-00E  855.45  791.09  -325.53
DE  S12-25-00E  1020.87 219.51  -996.99
EF  S83-44-00W  1117.26 -1110.58    -121.96
FA  N55-09-00W  660.08  -541.70 377.19