Yes, there is whitespace between each lat and lon on each line.  But, actually, 
I'd simply like to plot a dot at each location.  The '1' was there in my 
example because I do not yet know how to plot a particular symbol.  Here is 
what I got when I tried the code you just suggested. 

Traceback (most recent call last):
  File "test.py", line 319, in <module>
    (lat,lon)=line.strip().split(' ')
ValueError: too many values to unpack


There are 203 records in the data file.  Line 319 of test.py is this:

(lat,lon)=line.strip().split(' ')


--- On Tue, 4/19/11, Ian Bell <ib...@purdue.edu> wrote:

From: Ian Bell <ib...@purdue.edu>
Subject: Re: [Matplotlib-users] plotting points/locations from data file
To: "Michael Rawlins" <rawlin...@yahoo.com>
Cc: Matplotlib-users@lists.sourceforge.net
Date: Tuesday, April 19, 2011, 6:52 PM

To clarify, you are trying to read in a set of (lat,lon) points in a file that 
is space delimited, store the data, and then put a text marker at each point, 
with each point numbered in order?  The critical part is that you want to use a 
list (or numpy array) instead of a dictionary.  Something like this ought to do 
(don't have MPL on this computer though - pretty sure this should work):



lines=open('file.txt','r').readlines()
(lats,lons)=([],[])
for line in lines:
    (lat,lon)=line.strip().split(' ')
    lats.append(float(lat))
    lons.append(float(lon))



for i in range(len(lons)):
    plt.text(lats[i],lon[i],str(i+1),ha='center',va='center',color='white')

I'm sure there are a bunch of more compact ways to do this, but this should 
work.



Ian
----
Ian Bell
Graduate Research Assistant
Herrick Labs
Purdue University
email: ib...@purdue.edu
cell: (607)227-7626



On Tue, Apr 19, 2011 at 4:09 PM, Michael Rawlins <rawlin...@yahoo.com> wrote:




I'm trying to plot a series of points/locations on a map. I'm reading the 
latitudes and longitudes from a file, with each lat, lon pair on each record 
(line).  Here is the code:



def make_float(line):

    lati, longi = line.split()

    return float(lati), float(longi)



my_dict = {}

with open("file.txt") as f:

    for item in f:

        lati,longi = make_float(item)

        my_dict[lati] = longi



xpt,ypt = m(-76.1670,39.4670 )

plt.text(xpt,ypt,'1',color='white')



#print my_dict



The matplotlib code which I've previously used to plot a single point on the 
map is below, with longitude and latitude in ( ):



xpt,ypt = m(-70.758392,42.960445)

plt.text(xpt,ypt,'1',color='white')



When replacing (-70.758392,42.960445) with (longi,lati), the code plots only a 
single '1' at the location of just the last coordinate pair in the file. So now 
I only need to plot them all. Does the code I've implemented have an implicit 
loop to it?





Mike







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