在python上绘制坐标-使用哪种数据类型？

Question

I'm working on a task that involves isolating information from a CSV document (to be specific, the timestamp in nanoseconds and the latitude and longitude). I have managed to print these values successfully, but now I would like to plot it using matplotlib. This is my code so far:

import csv
from matplotlib import pyplot as plt

midnight = 1429574400
nsmidnight = 1429574400000000000
ifile  = open('(short file)Converted_radar_tracks_20150421_053822.csv', "rb")
reader = csv.DictReader(ifile, delimiter=';')

rownum = 0

for row in reader:#for each row
    if rownum == 0:
        header = row #define header row
    else:
        print "Timestamp:", long(row['timestamp'])*1000000000+nsmidnight+ int(row['timestamp_nsecs']),"Latitude:", float(row['lat']), "Longitude:", float(row['lon'])
        plt.plot('lat','lon')

    rownum += 1

plt.show()
ifile.close

However, when I run it, I get this error message:

ValueError: Unrecognized character l in format string

I think it may be because I am using the wrong data type for latitude and longitude. Does anyone have any suggestions to help me?

Answer 1

When you write plt.plot('lat','lon') , it is trying to plot the string lat with a format string lon . This does not work and gives you the error you see. What plt.plot() wants as arguments are lists of latitudes and longitudes. For example,

lat = [13, 26, 48]
lon = [51, 17, 19]
plt.plot(lat, lon)
plt.show()

Answer 2

plt.plot() takes a list or array of x and y pairs, not strings as you are passing with plt.plot('lat', 'lon') . The ValueError you are getting is due to this. Instead, put your values for latitude and longitude into a list or numpy array first, then pass them to plt.plot() like so:

lat = [41, 42, 43, 44, 45]
lon = [70, 71, 72, 73, 74]
plt.plot(lat, lon)