import pandas as pd
import matplotlib as plt
df = pd.read_csv("Steam data jan to aug 2021.csv")
df["Grade"] = df["Grade"].fillna(method="ffill")
df["steam kg/kg"] = df["Steam Flow to Dryers"]/df["PM4 Production Rate"]
gradeList = df["Grade"].unique().tolist()
for i in gradeList:
df1.loc([df["Grade"]==i])
plt.lineplot(x="steam kg/kg", y="Time", data=df1);