[Matplotlib-users] Query about streamplot

[Dhirendra Kumar]

Hii Adrien

Thanks for the reply. I have tried your example and could replicate it. But
in case of my script I have two variables:

*V* and *Omega* having sizes:
([('plev', 12), ('lat', 81)]))
([('plev', 12), ('lat', 81)]))

Plev has to be plotted on y axis and lat has to be plotted on x axis.

I am using following lines to create the plot:

plt.subplot(331)
plt.contourf(CC_W_CON11,cmap='RdBu')
plt.streamplot(X, Y, Omega,  V)

This gives me an error as:

  File
"/opt/apps/ANACONDA/lib/python3.7/site-packages/matplotlib/pyplot.py", line
2951, in streamplot
    if data is not None else {}))
  File
"/opt/apps/ANACONDA/lib/python3.7/site-packages/matplotlib/__init__.py",
line 1810, in inner
    return func(ax, *args, **kwargs)
  File
"/opt/apps/ANACONDA/lib/python3.7/site-packages/matplotlib/axes/_axes.py",
line 4882, in streamplot
    integration_direction=integration_direction)
  File
"/opt/apps/ANACONDA/lib/python3.7/site-packages/matplotlib/streamplot.py",
line 79, in streamplot
    grid = Grid(x, y)
  File
"/opt/apps/ANACONDA/lib/python3.7/site-packages/matplotlib/streamplot.py",
line 311, in __init__
    raise ValueError("The rows of 'x' must be equal")
*ValueError: The rows of 'x' must be equal*

Could you please look if there is any mistake ??

Thanks


On Wed, Apr 17, 2019 at 1:27 PM vincent.adrien at gmail.com <
vincent.adrien at gmail.com> wrote:

> Kumar,
>
> FWIW, based on the [streamplot
> example](
> https://matplotlib.org/gallery/images_contours_and_fields/plot_streamplot.html
> )
> in the gallery, the following snippet seems to be working just fine
> (with Matplotlib 3.0.1) “even though” the amount of X and Y coordinate
> values is (Nx, Ny) = (100, 50).
>
> ```python
> import numpy as np
> import matplotlib.pyplot as plt
>
> # Dummy data
> w = 3
> Nx, Ny = 100, 50
> Y, X = np.mgrid[-w:w:50j, -w:w:100j]
> U = -1 - X**2 + Y
> V = 1 + X - Y**2
>
> fig, ax = plt.subplots()
>
> ax.streamplot(X, Y, U, V)
> ax.set_title(f"{Nx/Ny:g}× more points along X than Y")
> ```
>
> Best,
> Adrien
>
> Le 17/04/2019 à 08:14, Adrien VINCENT a écrit :
> > Hi Kumar,
> >
> > Could provided a snippet with a (standalone) minimal working example of
> what you have tried ?
> >
> > AFAICT, looking at
> https://matplotlib.org/api/_as_gen/matplotlib.axes.Axes.streamplot.html
> it does not look like X and Y arrays of coordinates have to be of equal
> length (but the velocity arrays U and V should have relevant dimensions
> relative to X and Y).
> >
> > Best regards,
> > Adrien
> >
> >
> >
> > On April 16, 2019 11:05:01 PM GMT+02:00, Dhirendra Kumar <
> dhirendra.cub at gmail.com> wrote:
> >> Hii Folks
> >>
> >> I have an array with dimension (plev: 7, lat: 81). I was trying to draw
> >> streamline plot for Omega and V wind [Hadley cell].  I am facing some
> >> error
> >> with* plt.streamplot* as it says that both the dimension should be of
> >> equal
> >> size (i.e. N * N ). Is there any other way to create a streamline plot
> >> for
> >> the data having unequal values along both the dimensions?
> >>
> >> I seek help of the community in this regard.
> >>
> >> I hope I framed my question correctly.  Please let me know if I need to
> >> clarify more details.
> >>
> >> Thank you
> >
>
>

-- 
========================================
Dhirendra Kumar
PhD Student
School of Environmental Sciences, JNU
New Delhi (India)
Contact: +91 9910778043
Alternate email: dhirendra.cub at outlook.com
=========================================
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