Python - Plot time series data and connect two points using line

Question

While it seems not that difficult, for the life of me, I'm unable to figure this out. Any help will be greatly appreciated. Here is my scenario:

I have a dataframe, df1, that contains Date and Price. I can use this data to plot a graph using matplotlib.pyplot. Good so far.

I have another dataframe, df2, that contains again Date and Price information but only 6 rows. Now, I need to take the first two rows of df2and consider them as two points (x axis would be Date and y axis would be Price) and and connect them on the graph plotted above. Same with next two rows and so on. (there will be more rows in df2, but I hope you get the drift).

I tried calling plot() on both dfs one after the other - the result is that when df2.plot() is called, the graph plotted using df1.plot() is erased and df2 lines are plotted.

Below is how I need the result to look like.

cant you just use the plot() function from matplotlib.pyplot? — NemoMeMeliorEst, Jul 12 '19 at 12:57
I did, and it simply erases the df1 plot and plots df2 lines alone — Pavan Kulkarni, Jul 12 '19 at 13:02
do you call plt.show() both times, or just once in the bottom after both plot function calls? — NemoMeMeliorEst, Jul 12 '19 at 13:05
Show us some code (preferably a minimal working example). Without it we can only guess...... See https://stackoverflow.com/help/how-to-ask and https://stackoverflow.com/help/minimal-reproducible-example — Bart, Jul 12 '19 at 13:07
https://stackoverflow.com/questions/35363444/plotting-lines-connecting-points possible solution — user23564, Jul 12 '19 at 13:10

Brendan · Accepted Answer · 2019-07-12T13:43:50.423

4

df = pd.read_csv(r'https://vincentarelbundock.github.io/Rdatasets/csv/fpp2/goog200.csv', index_col=0)
df2 = df.loc[[57, 98, 169]]

plt.plot(df['time'], df['value'])
plt.plot(df2['time'], df2['value'])
plt.show()

Edit per comment

(Credit to user23564's linked answer in the comments to the OP)

df = pd.read_csv(r'https://vincentarelbundock.github.io/Rdatasets/csv/fpp2/goog200.csv', index_col=0)
df2 = df.loc[[57, 98, 169, 200]].reset_index()

plt.plot(df['time'], df['value'])
for i in range(0, len(df2), 2):
    plt.plot(df2.loc[i:i+1, 'time'], df2.loc[i:i+1, 'value'], c='grey')
plt.show()

edited Jul 12 '19 at 13:43

answered Jul 12 '19 at 13:10

Brendan

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Thanks Brendan! Though my mistake that I didn't upload the right image. I have edited the same. Could you pls check it? Thanks for your assistance – Pavan Kulkarni Jul 12 '19 at 13:27
Thanks Brendan! I ended up doing exactly this! Can't believe I couldn't figure such a simple solution earlier. Thanks for the help – Pavan Kulkarni Jul 12 '19 at 13:55

Python - Plot time series data and connect two points using line

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