title: How to add traces in plotly.express
body: <p>I am very new to python and plotly.express, and I find it very confusing...</p>
  <p>I am trying to use the principle of adding different traces to my figure, using example code shown here <a href="https://plotly.com/python/line-charts/" rel="noreferrer">https://plotly.com/python/line-charts/</a>, Line Plot Modes, #Create traces.</p>
  <p>BUT I get my data from a .CSV file.</p>
  <pre><code>import plotly.express as px
  import plotly as plotly
  import plotly.graph_objs as go
  import pandas as pd
  
  data = pd.read_csv(r&quot;C:\Users\x.csv&quot;)
  
  fig = px.scatter(data, x=&quot;Time&quot;, y=&quot;OD&quot;, color=&quot;C-source&quot;, size=&quot;C:A 1 ratio&quot;)
  
  fig = px.line(data, x=&quot;Time&quot;, y=&quot;OD&quot;, color=&quot;C-source&quot;)
  fig.show()
  </code></pre>
  <p>The above lines produces scatter/line plots with the correct data, but the data is mixed together. I have data from 2 different sources marked by a column named &quot;Strain&quot; in my .csv file that I would like the chart to reflect.</p>
  <p>Is the traces option a possible way to do it, or is there another way?</p>
  <p><a href="https://i.stack.imgur.com/o90RV.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/o90RV.jpg" alt="figure plotted with px.line" /></a></p>