How to build histogram subplots using pandas python

Question

I am attempting to plot 7 histograms to observe returns in the market. My code is below. It is throwing the following error

ValueError: x and y must have same first dimension, but have shapes (1230,) and (1,)

I do not understand this error because my check is confirming the data is set up correctly

>>> print(SPY['SPY'])

date
2013-07-16    151.7347
2013-07-17    152.1197
2013-07-18    152.9529
2013-07-19    153.2247
2013-07-22    153.5236
2013-07-23    153.1975



def plot_fat_tails():
    SPY = pdr.DataReader('SPY', 'iex', start, end).rename(columns={'close': 'SPY'})
    DIA = pdr.DataReader('DIA', 'iex', start, end).rename(columns={'close': 'DIA'})
    DAX = pdr.DataReader('DAX', 'iex', start, end).rename(columns={'close': 'DAX'})
    EWU = pdr.DataReader('EWU', 'iex', start, end).rename(columns={'close': 'EWU'})
    EWH = pdr.DataReader('EWH', 'iex', start, end).rename(columns={'close': 'EWH'})
    EWS = pdr.DataReader('EWS', 'iex', start, end).rename(columns={'close': 'EWS'})
    INDY = pdr.DataReader('INDY', 'iex', start, end).rename(columns={'close': 'INDY'})
    n_bins = 50
    fig, axs = plt.subplots(7, 1, sharex=True)
    # Remove horizontal space between axes
    fig.subplots_adjust(hspace=0)
    # Plot each graph, and manually set the y tick values
    axs[0].plot(SPY['SPY'], n_bins, density=True, histtype='bar')
    axs[1].plot(DIA['DIA'], n_bins, density=True, histtype='bar')
    axs[2].plot(DAX['DAX'], n_bins, density=True, histtype='bar')
    axs[3].plot(EWU['EWU'], n_bins, density=True, histtype='bar')
    axs[4].plot(EWH['EWH'], n_bins, density=True, histtype='bar')
    axs[5].plot(EWS['EWS'], n_bins, density=True, histtype='bar')
    axs[6].plot(INDY['INDY'], n_bins, density=True, histtype='bar')
    plot.show()

Corrected Code:

def plot_fat_tails():
    SPY = pdr.DataReader('SPY', 'iex', start, end).rename(columns={'close': 'SPY'})
    DIA = pdr.DataReader('DIA', 'iex', start, end).rename(columns={'close': 'DIA'})
    DAX = pdr.DataReader('DAX', 'iex', start, end).rename(columns={'close': 'DAX'})
    EWU = pdr.DataReader('EWU', 'iex', start, end).rename(columns={'close': 'EWU'})
    EWH = pdr.DataReader('EWH', 'iex', start, end).rename(columns={'close': 'EWH'})
    EWS = pdr.DataReader('EWS', 'iex', start, end).rename(columns={'close': 'EWS'})
    INDY = pdr.DataReader('INDY', 'iex', start, end).rename(columns={'close': 'INDY'})
    n_bins = 10
    fig, axs = plt.subplots(7, 1, sharex=True)
    # Remove horizontal space between axes
    fig.subplots_adjust(hspace=0)
    # Plot each graph, and manually set the y tick values
    axs[0].**hist**(SPY['SPY'], n_bins, density=True, histtype='bar')
    axs[1].**hist**(DIA['DIA'], n_bins, density=True, histtype='bar')
    axs[2].**hist**(DAX['DAX'], n_bins, density=True, histtype='bar')
    axs[3].**hist**(EWU['EWU'], n_bins, density=True, histtype='bar')
    axs[4].**hist**(EWH['EWH'], n_bins, density=True, histtype='bar')
    axs[5].**hist**(EWS['EWS'], n_bins, density=True, histtype='bar')
    axs[6].**hist**(INDY['INDY'], n_bins, density=True, histtype='bar')
    **fig.show()**

why is there a matlab tag if this question is all about python? — Anthony
– Anthony, Commented Jul 17, 2018 at 0:55

Diziet Asahi · Accepted Answer · 2018-07-17 11:14:47Z

1

I can't run your code (see How to create a Minimal, Complete, and Verifiable example) and I can't be sure where the error comes from since you did not include the full error message, including the line number... But here is my guess:

You say you are trying to plot a histogram, but you are using matplotlib's plot() which is used to plot a line with a similar number of x and y values. In this case, it's trying to plot SPY['SPY'] (shape (1230,)) as x, versus n_bins (shape (1,)) as y, hence the error message.

You should be using the hist() function instead:

axs[0].hist(SPY['SPY'], n_bins, density=True, histtype='bar')
(...)

answered Jul 17, 2018 at 11:14

Diziet Asahi

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