error in plotting the river mouths using the nextxy.bin dataset about pyflwdir HOT 7 CLOSED

The script your put here can identify all the river mouth pits.

Many thanks for your help!

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Hi @Jiangchao3, I believe the nextxy data is orientated North -> South (the first row is the most northern), which you also see in the xarray plot. Xarray jus plots the first row in the bottom based on nc contentions which dictate that data is oriented South -> North. To get the correct point locations you need to also make you lat array from north to south lat = np.linspace(90,-90,3600).

You can also parse the data with flw = pyflwdir.from_array(data, ftype='nextxy', transform=transform) and than use the idxs = flw.idxs_pit attribute in combination with the x, y = flw.xy(idxs) method to get the x, y location of outlets.

PS: To get a correct xarray plot you need to add the correct lat and lon dimension coordinates.

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Hi @DirkEilander ,

Thanks for your kindly reply. No error occured after using the lat =np.linspace(90,-90,3600).

And thanks for recommonding the idxs = flw.idxs_pit method. It works very well.

But it seems to find all the outlets (both -10 and -9), could I set a parameter to only find the outlet (-10) or outlet (-9)?
I have a try using the
idxs = flw.idxs_pit(-9) or
flw = pyflwdir.from_array(data,ftype='nextxy',idxs_pit='-9',latlon=True,transform = transform)
but boht failed.

Looking forward to your help!

Best,
Jiangchao

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Glad it works. We don't distinguish between different types of river outlets (-9) and inland pits (-10) in pyflwdir as most D8 flow direction types don't have this distinction. What you could do is after reading and parsing the nextxy data drop the locations corresponding to inland pits:

idxs = flw.idxs_pit
nextx = data[0]
idxs = idxs[nextx.flat[idxs] == -9]
x, y = flw.xy(idxs)

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Dear @DirkEilander, I am trying to get discharge timeseries from the CaMa-flood output data according to the (x,y) coordinate of the river outlets(-9).

I am not sure the rivermouth points obtained by x, y = flw.xy(idxs) is located at the center of each pits?

The following screensnaps shows the information of my CaMa-flood output discharge.

Could you please give me some suggestions on how to get discharges of each rivermouth pit?

Many thanks!

Jiangchao

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I am not sure the rivermouth points obtained by x, y = flw.xy(idxs) is located at the center of each pits?

The coordinates obtained with that function should be at the center of the cell if the transform is set well when initializing flw.

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The coordinates obtained with that function should be at the center of the cell if the transform is set well when initializing flw.

Got it. Thanks for your relply.

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