You are trying to plot the data that is very large when compared to the resolution of your monitor. This is the reason for you seeing the points as a continuous line. This is just a visualisation issue as the data is discrete. Try performing the following steps to have a proper visualisation:
- Try downsampling your data because such a large data cannot be visualised as separate points because of the resolution issue.
- One more way is to try reducing the markersize, which in turn will make the plot appear as you wanted.
If you need to modify the Markersize you can do as shown below:
For more information regarding plotting of data check Plot. You can also refer stem documentation which plots the discrete sequence data.