Extracting data from a txt-file - file-io

Question

I got some input in a txt file which I attached below. I want to extract the variables x1 to x6 where the values are in the first colum after the colon. (For example for the first x2 -1.55155599552781E+00)
I tried already:
data = textscan(fileID,'%s %s %f %f %f')
But that did not work. What would be the best way to do this?
729 6
===========================================================================
solution 1 :
t : 1.00000000000000E+00 0.00000000000000E+00
m : 1
the solution for t :
x2 : -1.55155599552781E+00 -2.39714921318749E-46
x4 : -2.01518902001522E+00 1.29714616910194E-46
x1 : 1.33015840530650E+00 2.03921256321194E-46
x6 : -2.10342596985387E+00 1.19910915953576E-46
x3 : 1.27944237849516E+00 1.99067515607667E-46
x5 : 2.44955616711054E+00 -1.48359823527798E-46
== err : 2.178E-13 = rco : 2.565E-05 = res : 1.819E-11 ==
solution 2 :
t : 1.00000000000000E+00 0.00000000000000E+00
m : 1
the solution for t :
x2 : 1.55762648294693E+00 1.44303635803762E-45
x4 : 2.10025771786320E+00 -6.97912321099274E-46
x1 : -1.28451613237821E+00 -1.19859598871142E-45
x6 : 2.01187184051108E+00 -7.54361111776421E-46
x3 : -1.33529118239379E+00 -1.22818883958157E-45
x5 : -2.44570040628148E+00 8.62982269594568E-46
== err : 2.357E-13 = rco : 2.477E-05 = res : 1.637E-11 ==

Answer 1

You don't mention what platform you're on or what tools you have available, but here's one way using awk:
$ awk '/^ x[1-6]/{print $3}' your_input
-1.55155599552781E+00
-2.01518902001522E+00
1.33015840530650E+00
-2.10342596985387E+00
1.27944237849516E+00
2.44955616711054E+00
1.55762648294693E+00
2.10025771786320E+00
-1.28451613237821E+00
2.01187184051108E+00
-1.33529118239379E+00
-2.44570040628148E+00
or, like this:
$ awk '/^ x[1-6]/{print $1, $3}' f1
x2 -1.55155599552781E+00
...
or using grep and cut:
$ grep '^ x[1-6]' your_input | cut -d' ' -f-4,5
x2 : -1.55155599552781E+00
...
Perl:
perl -lane 'print $F[2] if /^ x[1-6]/' your_input
Stupid and simple Python:
#!/usr/bin/env python
with open("f1") as fd:
for line in fd:
if line.startswith(' x'):
print line.strip().split()[2]
sed:
$ sed -n 's/^ x[1-6] : *\([^ ]*\).*$/\1/p' your_input

Answer 2

In Python this should do it
import re
vars = {}
for x in open("data.txt"):
m = re.match("^\\s+(x\\d+)\s+:\\s+([^ ]*).*", x)
if m:
vars[m.group(1)] = float(m.group(2))
if re.match("^== err.*", x):
# Got a full solution
print vars
vars = {}
When a full solution is found the variables are available as
vars['x1']
vars['x2']
already converted to floating point numbers