plt.legend() when plotting multiple dataframes in a for loop-CodePudding

suppose i have three dataframes

df1 = pd.DataFrame({"A" : [1,2,3], "B" : [4,5,6]})
df2 = pd.DataFrame({"A" : [2,5,3], "B" : [7,3,1]})
df3 = pd.DataFrame({"A" : [1,2,1], "B" : [5,3,6]})

I put all three dataframes in a list to perform an identical operation on all three dataframes

dframes = [df1, df2, df3]
for frame in dframes:
   frame["C"] = frame["A"]   frame["B"]
   plt.plot(frame["C"])

works like a charm. my problem: when i want to add a legend. plt.legend() throws

No artists with labels found to put in legend.

plt.legend(frame) uses the names of the columns in the dataframes, i.e.,

"A", "B" & "C"

and not as desired

"df1", "df2", "df3"

how can i grab the correct line handles ?

CodePudding user response：

As mentioned in the message you've received after trying

Update. Example using a dict and using the keys for the labels:

dframes = {'ll_800': df1, 'll_600wo_200': df2, 'wo_800': df3}
for k, v in dframes.items():
    v["C"] = v["A"]   v["B"]
    plt.plot(v["C"], label=k)
plt.legend(bbox_to_anchor=[1,1])
plt.show()

Result