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Publish messages from a .csv file the appropriate way

asked 2021-06-09 02:38:12 -0500

congphase gravatar image

Hello all,

I extracted data from the GPS topic in my recorded bag file into a .csv file. I then modified the lat,lon values to create fake data as desire. Now I want to write a node to publish that modified data to mapviz.

What I expect to do is (with Python API):

  1. Parse the .csv file into a junk of NavSatFix data object
  2. Loop through that object to publish each messages (similar to each row in the .csv at first)

But I haven't found any tutorial with similar idea. Most of them performs something like

def talker():   
print('in talker')
pub = rospy.Publisher('GPS', NavSatFix, queue_size=10)
rospy.init_node('GPStalker', anonymous=True)
while not rospy.is_shutdown():
    #Assuming that parse will return these values
    time.sleep(1)
    # build navsat message
    fake_gps = NavSatFix()
    fake_gps.header.frame_id = ''
    fake_gps.header.stamp = rospy.Time.now()
    fake_gps.status.status = 1
    fake_gps.status.service = 2
    fake_gps.latitude = 3
    fake_gps.longitude = 4
    fake_gps.altitude = 5

    pub.publish(fake_gps)

My question is, is there a way to implement my idea? Is it efficient? Can you give me some documents or tutorials?

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Comments

Hello,

Can you please! tell me the columns and how many rows of your CSV file?

Ranjit gravatar image Ranjit  ( 2021-06-09 03:07:18 -0500 )edit

Hi @Ranjit,

My csv file has 15 columns:

rosbagTimestamp,header,seq,stamp,secs,nsecs,frame_id,status,status,service,latitude,longitude,altitude,position_covariance,position_covariance_type

and 352 rows, including the headers.

congphase gravatar image congphase  ( 2021-06-09 03:18:16 -0500 )edit

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answered 2021-06-09 03:26:40 -0500

Ranjit gravatar image

updated 2021-06-09 03:34:03 -0500

Hello @congphase,

I think with this code you can able to read the csv file row one by one and publish it. Note: for example you want the data for rosbagTimestamp it is presented at 0 location so to obtain that data you need to make print(row[0]) similarly with others.

import csv
# Code inside your while loop
with open('csv_file_name.csv', 'r') as file:
    reader = csv.reader(file)
    for row in reader:
        print(row)

You can also use pandas, NumPy so many libraries. You just have to install this using the pip command.

I hope you got your answer if you have any questions or issue with the answer please! drop comment.

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Asked: 2021-06-09 02:38:12 -0500

Seen: 13 times

Last updated: Jun 09