too many indices for array with matplotlib subplots

Question

I'm trying to plot 2 different data sets but I don't know how to fix the subplot (if i put 2,2 it works but if i try anything else it gives me an error)

fig, axs = plt.subplots(nrows=2, ncols=1)

axs[0,1].plot(adj_close['SOL-USD'])
axs[2,1].set_title('SOL')

plt.show()

error:


----> 6 axs[0,0].plot(adj_close['SOL-USD'])
      7 axs[0,0].set_title('SOL')
      8 axs[0,1].plot(adj_close['ETH-USD'])

TypeError: 'AxesSubplot' object is not subscriptable

IndexError                                Traceback (most recent call last)
Input In [356], in <cell line: 3>()
      1 #ploting the histogram
      2 fig, axs = plt.subplots(2,1,figsize=(16,8),gridspec_kw ={'hspace': 0.2, 'wspace': 0.1})
----> 3 axs[0,0].hist(returns['SOL-USD'], bins=50, range=(-0.2, 0.2))
      4 axs[0,0].set_title('SOL')
      5 axs[1,0].hist(returns['ETH-USD'], bins=50, range=(-0.2, 0.2))

IndexError: too many indices for array: array is 1-dimensional, but 2 were indexed

what it currently looks like with subplot 2,2:

Welcome back to Stack Overflow. Please read How to Ask and minimal reproducible example, and make sure to show 1) code that someone else can copy and paste, without changing anything, to reproduce the exact problem (and not something else); 2) a complete error message that corresponds to the code shown. In the example, it's not clear whether axs is a typo for axes, or meant to refer to a different variable not shown; and the error message clearly shows code that doesn't reflect the code in the example. (Also, please try to ask a question instead of just showing code and an error.) — Karl Knechtel
– Karl Knechtel, Commented Jun 27, 2022 at 1:33
@KarlKnechtel hi there, i don't think axs is a typo because when i change plt.subplots(nrows=2, ncols=1) to plt.subplots(nrows=2, ncols=2) it gets graphed :( — catlean
– catlean, Commented Jun 27, 2022 at 1:39
fig, axs = plt.subplots(2,2,figsize=(16,8),gridspec_kw ={'hspace': 0.2, 'wspace': 0.1}) — catlean
– catlean, Commented Jun 27, 2022 at 1:41
sorry i tried to go in and edit it but i think i pasted the wrong code — catlean
– catlean, Commented Jun 27, 2022 at 1:42

kmontocam · Accepted Answer · 2022-06-27 01:49:53Z

3

what is going on here is that matplotlib.pyplot.subplots() creates an array of one dimension for axes in fig if nrows or ncols is equal to 1. You can see this by displaying the variable in your current workspace.

>>> fig, axes = plt.subplots(nrows=2, ncols=1)

>>> axes

array([<AxesSubplot:>, <AxesSubplot:>], dtype=object)

That is why an index error appears when trying to call more than one. For more documentation, here is the site to the function matplotlib.pyplot.subplots

edited Jun 27, 2022 at 1:49

answered Jun 27, 2022 at 1:47

kmontocam

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3 Comments

Karl Knechtel Over a year ago

Ew. Unfortunate design, IMO. Special cases aren't special enough to break the rules.

Michael Delgado Over a year ago

agreed. it's not a great default

Michael Delgado Over a year ago

Answer #2 ever and you fired off something high quality this fast? I'm impressed :) welcome to stack overflow!

Michael Delgado · Accepted Answer · 2022-06-27 01:50:20Z

See the matplotlib.pyplot.subplots documentation. There is an optional argument squeeze, default True:

squeeze : bool, default: True
If True, extra dimensions are squeezed out from the returned array of Axes:

if only one subplot is constructed (nrows=ncols=1), the resulting single Axes object is returned as a scalar.

for Nx1 or 1xM subplots, the returned object is a 1D numpy object array of Axes objects.

for NxM, subplots with N>1 and M>1 are returned as a 2D array.

If False, no squeezing at all is done: the returned Axes object is always a 2D array containing Axes instances, even if it ends up being 1x1.

So, with the default of squeeze=True, axes will be a different shape depending on your arguments:

plt.subplots(1, 1) --> single Axis object
plt.subplots(1, n) --> 1-dimensional vector of Axis objects
plt.subplots(n, 1) --> 1-dimensional vector of Axis objects
plt.subplots(n, m) --> 2-dimensional array of Axis objects

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