#Python, matplotlib
from matplotlib import pyplot as plt

#Create the regular line graph with plt.plot, then add the marker argument.
plt.plot(df["col1"], marker='o')

#Example of a few markers:
   -                solid line style
   --               dashed line style
   -.               dash-dot line style
   :                dotted line style
   .                point marker
   ,                pixel marker
   o                circle marker