For my calculations, I need increased precision of parameter 'k' in my Manipulate:

Manipulate[
 Plot[Cos[k x], {x, 0, 2 Pi}], {{k, 1}, 0, SetPrecision[4.0, 22], 
  SetPrecision[0.100, 22], Appearance -&gt; "Labeled"}]


However, at the same time, for aesthetic reasons, I want the label to the right of the slider to display only couple of digits.

How this could be done?


Question: Find Nearest Line Segments to Point
Answer: I have reproduced your example with shapefiles. 

You can use Shapely and Fiona to solve your problem.

1) Your problem (with a shapely Point):



2) starting with an arbitrary line (with an adequate length):

from shapely.geometry import Point, LineString
line = LineString([(point.x,point.y),(final_pt.x,final_pt.y)])




3) using shapely.affinity.rotate to create the radii (rotating the line from the point, look also the Mike Toews's answer at Python, shapely library: is it possible to do an affine operation on shape polygon?):

from shapely import affinity
# Rotate i degrees CCW from origin at point (step 10°)
radii= [affinity.rotate(line, i, (point.x,point.y)) for i in range(0,360,10)]




4) now, using shapely:cascaded_union (or shapely:unary_union) to get a MultiLineString:

from shapely.ops import cascaded_union
mergedradii = cascaded_union(radii)
print mergedradii.type
MultiLineString


5) the same with the original lines (shapefile)

import fiona
from shapely.geometry import shape
orlines = fiona.open("orlines.shp")
shapes = [shape(f['geometry']) for f in orlines]
mergedlines = cascaded_union(shapes)
print mergedlines.type
MultiLineString


6) the intersection between the two multigeometries is computed and the result is saved to a shapefile:

 points =  mergedlines.intersection(mergedradii)
 print points.type
 MultiPoint
 from shapely.geometry import mapping
 schema = {'geometry': 'MultiPoint','properties': {'test': 'int'}}
 with fiona.open('intersect.shp','w','ESRI Shapefile', schema) as e:
      e.write({'geometry':mapping(points), 'properties':{'test':1}})


Result:



7) but, problem, if you use a a longer radius, the result is different:



8) And if you want to get your result, you need to select only the point with the shortest distance from the original point on a radius:

points_ok = []
for line in mergeradii:
   if line.intersects(mergedlines):
       if line.intersection(mergedlines).type == "MultiPoint":
          # multiple points: select the point with the minimum distance
          a = {}
          for pt in line.intersection(merged):
              a[point.distance(pt)] = pt
          points_ok.append(a[min(a.keys())])
       if line.intersection(mergedlines).type == "Point":
          # ok, only one intersection
          points_ok.append(line.intersection(mergedlines))
solution = cascaded_union(points_ok)
schema = {'geometry': 'MultiPoint','properties': {'test': 'int'}}
with fiona.open('intersect3.shp','w','ESRI Shapefile', schema) as e:
     e.write({'geometry':mapping(solution), 'properties':{'test':1}})


Final result:



I hope that is what you want.