[FIXED] Why defined subplots within for-loop behave inconsistently? ('numpy.ndarray' object has no attribute 'plot')

Issue

I want to generate several subplots within a for loop, but always get the AttributeError: 'numpy.ndarray' object has no attribute 'plot'.

measurements = 9

fig, axs = plt.subplots(3,(measurements+2)//3, sharey=False, gridspec_kw={'wspace': 0.1},figsize =(20, 10))
for i in range(0,measurements):    
    try:
        axs[0].plot(dfrld_1['RLD date(' + str(i) + ')'], dfrld_1['Depth'],lw=2, color=next(red1))
        axs[1].plot(dfrld_2['RLD date(' + str(i) + ')'], dfrld_2['Depth'],lw=2, color=next(red1))
        axs[2].plot(dfrld_3['RLD date(' + str(i) + ')'], dfrld_3['Depth'],lw=2, color=next(red1))
        axs[3].plot(dfrld_4['RLD date(' + str(i) + ')'], dfrld_4['Depth'],lw=2, color=next(red1))
        axs[4].plot(dfrld_5['RLD date(' + str(i) + ')'], dfrld_5['Depth'],lw=2, color=next(red1))
        axs[5].plot(dfrld_6['RLD date(' + str(i) + ')'], dfrld_6['Depth'],lw=2, color=next(red1))
        axs[6].plot(dfrld_7['RLD date(' + str(i) + ')'], dfrld_7['Depth'],lw=2, color=next(red1))
        axs[7].plot(dfrld_8['RLD date(' + str(i) + ')'], dfrld_8['Depth'],lw=2, color=next(red1))
        axs[8].plot(dfrld_9['RLD date(' + str(i) + ')'], dfrld_9['Depth'],lw=2, color=next(red1))
    except KeyError:
        pass
plt.show()

All dataframes (dfrld_1, dfrld2,...) have the same format.

   Depth  RLD date(1)  RLD date(2)  RLD date(3)  RLD date(4)  RLD date(5)  RLD date(6)  RLD date(7)  RLD date(8)  RLD date(9)
0    -10          0.0          0.0     0.135132     0.697177     0.815027     0.571775     0.467736     0.152040     0.168436
1    -20          0.0          0.0     0.059295     0.286268     0.383652     0.218391     0.155417     0.065664     0.057106
2    -40          0.0          0.0     0.000000     0.052796     0.151876     0.297082     0.304435     0.268104     0.247111
3    -60          0.0          0.0     0.000000     0.000000     0.090140     0.145970     0.196542     0.148141     0.145210
4    -80          0.0          0.0     0.000000     0.000000     0.000000     0.000000     0.135144     0.124805     0.114642

The exact error I get is:

AttributeError: 'numpy.ndarray' object has no attribute 'plot' 

With anoather dataframe, which look the same and only 3 subplots this is working without any problems. But here I cannot find my mistake.

Solution

The problem is that axs is a numpy array with shape (3,3) and not (9, 1) as you expect I think in your code.

Try:

measurements = 9

fig, axs = plt.subplots(3,(measurements+2)//3, sharey=False, gridspec_kw={'wspace': 0.1},figsize =(20, 10))
for i in range(0,measurements):    
    try:
        axs[0][0].plot(dfrld_1['RLD date(' + str(i) + ')'], dfrld_1['Depth'],lw=2, color=next(red1))
        axs[0][1].plot(dfrld_2['RLD date(' + str(i) + ')'], dfrld_2['Depth'],lw=2, color=next(red1))
        axs[0][2].plot(dfrld_3['RLD date(' + str(i) + ')'], dfrld_3['Depth'],lw=2, color=next(red1))
        axs[1][0].plot(dfrld_4['RLD date(' + str(i) + ')'], dfrld_4['Depth'],lw=2, color=next(red1))
        axs[1][1].plot(dfrld_5['RLD date(' + str(i) + ')'], dfrld_5['Depth'],lw=2, color=next(red1))
        axs[1][2].plot(dfrld_6['RLD date(' + str(i) + ')'], dfrld_6['Depth'],lw=2, color=next(red1))
        axs[2][0].plot(dfrld_7['RLD date(' + str(i) + ')'], dfrld_7['Depth'],lw=2, color=next(red1))
        axs[2][1].plot(dfrld_8['RLD date(' + str(i) + ')'], dfrld_8['Depth'],lw=2, color=next(red1))
        axs[2][2].plot(dfrld_9['RLD date(' + str(i) + ')'], dfrld_9['Depth'],lw=2, color=next(red1))
    except KeyError:
        pass
plt.show()

Answered By - Florian Gacon