Selecting Specific Time Steps for Rainfall Data Visualization

[haritha1022]

What happened?

i just want plot particular time steps variable data
define rain=((rainnc(t=17))-rainnc(t=9)))
how can do it in python
any idea

What did you expect to happen?

i want data only some time steps
how can i eleminate other timesteps

Minimal Complete Verifiable Example

import xarray as xr
import cartopy.crs as ccrs
from cartopy import feature as cf
import matplotlib.pyplot as plt
import numpy as np

#Opening and reading data
data=xr.open_dataset("heavyrain3.nc")
print(data)


lon=data.lon[:]
lat=data.lat[:]


#lev_2=data.lev_2[:]

rainnc=data.rainnc[17-9]
#time=data.time[0]







ax = plt.axes(projection=ccrs.PlateCarree())

rainnc.isel(time=16, lev_2=0).plot.pcolormesh(cmap='Purples',add_colorbar=False);


#ax.set_extent([west, east, south, north])
ax.coastlines()
ax.add_feature(cf.BORDERS)

plt.savefig("rain31.jpg")
plt.show()

Relevant log output

raise ValueError(
ValueError: Dimensions {'time'} do not exist. Expected one or more of ('lev_2', 'lat', 'lon')

Anything else we need to know?

No response

Environment

Traceback (most recent call last):
File "/home/user/Documents/IGCAR/rain/rain.py", line 39, in
rainnc.isel(time=16, lev_2=0).plot.pcolormesh(cmap='Purples',add_colorbar=False);
File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/core/dataarray.py", line 1208, in isel
variable = self._variable.isel(indexers, missing_dims=missing_dims)
File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/core/variable.py", line 1190, in isel
indexers = drop_dims_from_indexers(indexers, self.dims, missing_dims)
File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/core/utils.py", line 834, in drop_dims_from_indexers
raise ValueError(
ValueError: Dimensions {'time'} do not exist. Expected one or more of ('lev_2', 'lat', 'lon')

[max-sixty]

Please review the links on producing quality examples. I'll close for now but feel free to reopen if you're up for producing one.

[haritha1022]

import xarray as xr
import cartopy.crs as ccrs
from cartopy import feature as cf
import matplotlib.pyplot as plt
import numpy as np

data=xr.open_dataset("rainncreq.nc")
print(data)
lon=data.lon[:]
lat=data.lat[:]
lev_2=data.lev_2[0]
rainnc=data.rainnc[:]
ax = plt.axes(projection=ccrs.PlateCarree())
rainnc.isel(time=0+8,lev_2=0).plot.pcolormesh(cmap='jet',vmax=100,vmin=0,add_colorbar=True);
ax.coastlines()
ax.add_feature(cf.BORDERS)
plt.savefig("rain31.jpg")
plt.show()

then it is not giving error just the data
but actually i want add the the time steps from 0 to 8
when i was 0+1+2+3....+8
then it is giving index error

File "/home/user/Documents/IGCAR/rain/rain.py", line 36, in <module>
    rainnc.isel(time=0+1+2+3+4+5+6+7+8,lev_2=0).plot.pcolormesh(cmap='jet',vmax=100,vmin=0,add_colorbar=True);
  File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/core/dataarray.py", line 1208, in isel
    variable = self._variable.isel(indexers, missing_dims=missing_dims)
  File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/core/variable.py", line 1193, in isel
    return self[key]
  File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/core/variable.py", line 786, in __getitem__
    data = as_indexable(self._data)[indexer]
  File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/core/indexing.py", line 555, in __getitem__
    return type(self)(_wrap_numpy_scalars(self.array[key]))
  File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/core/indexing.py", line 524, in __getitem__
    return type(self)(_wrap_numpy_scalars(self.array[key]))
  File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/core/indexing.py", line 431, in __getitem__
    return type(self)(self.array, self._updated_key(indexer))
  File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/core/indexing.py", line 403, in _updated_key
    full_key.append(_index_indexer_1d(k, next(iter_new_key), size))
  File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/core/indexing.py", line 176, in _index_indexer_1d
    indexer = _expand_slice(old_indexer, size)[applied_indexer]
IndexError: index 36 is out of bounds for axis 0 with size 9

hope you understand my problem

[dcherian]

Please see https://docs.xarray.dev/en/stable/user-guide/indexing.html#indexing-with-dimension-names particularly the examples using slice. This syntax is similar to standard python syntax for lists, strings, and tuples. For example,see https://towardsdatascience.com/mastering-indexing-and-slicing-in-python-443e23457125

[haritha1022]

good morning sir slice working on latitude and longitude but it is not working on time when i give slice to time it giving error ```pytb Traceback (most recent call last): File "/home/user/Documents/IGCAR/rain/rain.py", line 36, in <module> rainnc.isel(time=slice(0,8),lev_2=0).plot.pcolormesh(cmap='jet',vmax=100,vmin=0,add_colorbar=True); File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/plot/plot.py", line 1302, in plotmethod return newplotfunc(**allargs) File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/plot/plot.py", line 1132, in newplotfunc xlab, ylab = _infer_xy_labels( File "/home/user/anaconda3/lib/python3.9/site-packages/xarray/plot/utils.py", line 390, in _infer_xy_labels raise ValueError("DataArray must be 2d") ValueError: DataArray must be 2d ```

[keewis]

to answer that we need more information. Can you post the output of print(rainnc)?

[haritha1022]

yeah sure

 Dimensions:  (time: 9, lon: 378, lat: 351, lev_2: 1)
Coordinates:
  * time     (time) datetime64[ns] 2021-12-30 2021-12-30T03:00:00 ... 2021-12-31
  * lon      (lon) float64 77.43 77.45 77.46 77.47 ... 81.32 81.33 81.34 81.35
  * lat      (lat) float64 11.14 11.15 11.16 11.17 ... 14.65 14.66 14.67 14.68
  * lev_2    (lev_2) float64 1e+03
Data variables:
    rainnc   (time, lev_2, lat, lon) float32 ...

[keewis]

The error is raised because pcolormesh needs a 2D array but the slice returns a 3D array ((time, lat, lon)). To fix that, you can try plotting each time separately by passing col="time". If that's not what you wanted, can you describe what you wanted to do?

[earthtech23]

Hello @keewis

I have a similar error to the one referred to the thread. I am already using col="time" to plot time series of satellite images (sentinel-2) and stills having the error ValueError: DataArray must be 2d

Any other ideas?

[haritha1022]

actually i want add the rainnc value from time step 0 to 8

…

On Thu, Feb 10, 2022 at 2:33 PM keewis ***@***.***> wrote: The error is raised because pcolormesh needs a 2D array but the slice returns a 3D array ((time, lat, lon)). To fix that, you can try plotting each time separately by passing col="time". If that's not what you wanted, can you describe what you wanted to do? — Reply to this email directly, view it on GitHub <#6261 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AXIX2YDP4C6KI5M2DYEVPOTU2N5O5ANCNFSM5N6E647A> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you authored the thread.Message ID: ***@***.***>

[haritha1022]

i want to plot total rainnc data in a single plot i want add the rainnc timesteps On Thu, Feb 10, 2022 at 2:35 PM haritha meka ***@***.***> wrote:

…

actually i want add the rainnc value from time step 0 to 8 On Thu, Feb 10, 2022 at 2:33 PM keewis ***@***.***> wrote: > The error is raised because pcolormesh needs a 2D array but the slice > returns a 3D array ((time, lat, lon)). To fix that, you can try plotting > each time separately by passing col="time". If that's not what you > wanted, can you describe what you wanted to do? > > — > Reply to this email directly, view it on GitHub > <#6261 (reply in thread)>, > or unsubscribe > <https://github.com/notifications/unsubscribe-auth/AXIX2YDP4C6KI5M2DYEVPOTU2N5O5ANCNFSM5N6E647A> > . > Triage notifications on the go with GitHub Mobile for iOS > <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> > or Android > <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. > > You are receiving this because you authored the thread.Message ID: > ***@***.***> >

[keewis]

then you're looking for

rainnc.isel(time=slice(0, 8), lev_2=0).sum(dim="time")

which sums up the 8 time steps between the 0th and 7th (slices are right-exclusive)

[haritha1022]

actually there are 9 time steps

[keewis]

then you have to use slice(0, 9)

[haritha1022]

I will try sir
thank you sir

[haritha1022]

Thanks a lot. it works sir

…

On Thu, Feb 10, 2022 at 2:50 PM keewis ***@***.***> wrote: then you have to use slice(0, 9) — Reply to this email directly, view it on GitHub <#6261 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AXIX2YE44W7O4WKKDVXT73DU2N7O3ANCNFSM5N6E647A> . Triage notifications on the go with GitHub Mobile for iOS <https://apps.apple.com/app/apple-store/id1477376905?ct=notification-email&mt=8&pt=524675> or Android <https://play.google.com/store/apps/details?id=com.github.android&referrer=utm_campaign%3Dnotification-email%26utm_medium%3Demail%26utm_source%3Dgithub>. You are receiving this because you authored the thread.Message ID: ***@***.***>