loop through two dataframes and plot by column in loop

user_11958450 0
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I have 2 dataframes with the same column names, index and size. I want to create a scatterplot of one dataframe column vs the other with the same header. When I try the code below, only the sim.columns are looping, while the obs.columns plots only the first column and don't loop. So what I get are scatter plots of each sim.columns against the first obs.column only. I'm not sure what is messed up with this loop. Thanks for your help!

    obs= pd.read_csv(obsFile)
    obs.rename(columns={obs.columns[0]: "SP" }, inplace = True)
    sim= pd.read_csv(simFile)
    sim.rename(columns={sim.columns[0]: "SP" }, inplace = True)
    
sim = sim.set_index("SP")
obs = obs.set_index("SP")

for colsim in sim.columns:
    for colobs in obs.columns:
        axes = plt.gca()
        axes.set_xlim([1,630])
        plt.scatter(sim.index, sim[colsim])
        plt.scatter(obs.index, obs[colobs])

        plt.xlabel('Stress Period')
        plt.ylabel('groundwater elevation(m)')
        plt.title(str(colsim))
        plt.savefig(os.path.join(outFold, str(colsim)+'.pdf')) 
        plt.close()
        break
pandas dataframe plot python loops
2 Answers

Instead of a double for loop:

for colsim in sim.columns:
    for colobs in obs.columns:
        ...

Just use a zip:

for colsim, colobs in zip(sim.columns, obs.columns):
    ...

Not sure what you mean with what you wanna do, but if this code doesn't work, try removing the break then it should work, but if it works without removing the break just keep it.

user_87083640

You shouldn't use a nested loop here, it does not what you want to achieve. Instead you want to loop through both dataframes at the same time in one loop. i can think of 2 ways how to achieve this:

  1. merge the dataframes and loop through the merged dataframe in one loop
  2. introduce a counter variable which can be used as an index for looping through both dataframes parallel
user_145735210
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