# 'slowness' error while using stream.ppoints()

**URL:** <https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008>\
**Category:** Related: rf\
**Created:** [July 28, 2020, 1:17pm UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008 "2020-07-28T13:17:00Z")\
**Posts on this page:** 17\
**Page:** 1

<div class="post-metadata">

**Author:** ![Sarenrenegade](https://discourse.obspy.org/letter_avatar_proxy/v4/letter/s/47e85d/32.png) [@Sarenrenegade](https://discourse.obspy.org/u/Sarenrenegade)\
**Post date:** [July 28, 2020, 1:17pm UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/1 "2020-07-28T13:17:00Z")

</div>

Hello! I’m trying to determine peircing points using rf. I’m new to python and I’m not quite sure I understood the doc correctly. Can anyone help me out?

Here’s my code:

```
from rf import read_rf
stream = read_rf('ev1.SAC')
stream.ppoints(50,'P')

```

Here’s the error:

```
C:\Users\Maureen\anaconda3\lib\site-packages\obspy\core\trace.py:220: UserWarning: Calibration factor set to 0.0!
  warnings.warn(msg, UserWarning)
Traceback (most recent call last):

  File "C:\Users\Maureen\Documents\M1 Stage\Python\PyTauP_test.py", line 11, in <module>
    stream.ppoints(50,'P')

  File "C:\Users\Maureen\anaconda3\lib\site-packages\rf\rfstream.py", line 391, in ppoints
    model.ppoint(tr.stats, pp_depth, phase=pp_phase)

  File "C:\Users\Maureen\anaconda3\lib\site-packages\rf\simple_model.py", line 229, in ppoint
    dr = self.ppoint_distance(depth, stats['slowness'], phase=phase)

  File "C:\Users\Maureen\anaconda3\lib\site-packages\obspy\core\trace.py", line 235, in __getitem__
    return super(Stats, self). __getitem__ (key, default)

  File "C:\Users\Maureen\anaconda3\lib\site-packages\obspy\core\util\attribdict.py", line 74, in __getitem__
    return self. __dict__ [name]

KeyError: 'slowness'

```

---

<div class="post-metadata">

**Author:** ![trichter](https://discourse.obspy.org/user_avatar/discourse.obspy.org/trichter/32/226_2.png) [@trichter](https://discourse.obspy.org/u/trichter)\
**Post date:** [July 28, 2020, 3:51pm UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/2 "2020-07-28T15:51:00Z")

</div>

Hello!

To calculate the piercing point the slowness of the ray has to be known.  
Can you upload your file `ev1.SAC` or post the output of `print(stream[0].stats)`?

---

<div class="post-metadata">

**Author:** ![Sarenrenegade](https://discourse.obspy.org/letter_avatar_proxy/v4/letter/s/47e85d/32.png) [@Sarenrenegade](https://discourse.obspy.org/u/Sarenrenegade)\
**Post date:** [July 28, 2020, 4:44pm UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/3 "2020-07-28T16:44:42Z")

</div>

Thanks for your answer. Ok, I thought that the module was using as input iasp97 (or something like that ) as a velocity model 🤔 I’ve uploaded the file. But it seems that I have a problem because now I get an error “no module named rf” when I run the previous code… I’m the right environment but something’s wrong and I can’t understand why…When I run conda activate rfenv, sets path for LIB and CPATH or does this mean that I missed a step in the installation process? I’m using spyder as python interpreter.

(Attachment ev1.SAC is missing)

---

<div class="post-metadata">

**Author:** ![Sarenrenegade](https://discourse.obspy.org/letter_avatar_proxy/v4/letter/s/47e85d/32.png) [@Sarenrenegade](https://discourse.obspy.org/u/Sarenrenegade)\
**Post date:** [July 28, 2020, 4:49pm UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/4 "2020-07-28T16:49:11Z")

</div>

I couldn’t upload the SAC file “unauthorized”…

---

<div class="post-metadata">

**Author:** ![trichter](https://discourse.obspy.org/user_avatar/discourse.obspy.org/trichter/32/226_2.png) [@trichter](https://discourse.obspy.org/u/trichter)\
**Post date:** [July 28, 2020, 5:19pm UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/5 "2020-07-28T17:19:02Z")

</div>

Yes the iasp model is used by default, but to calculate piercing points you need to know something about the incoming ray.

I think when you want to use rf in spyder, you need to install rf into the same environment spyder is installed in. You can check the installed packages with `conda list`.

> I couldn’t upload the SAC file “unauthorized”…

What a pitty, maybe we can improve on that, see [Upload attachments to post](https://discourse.obspy.org/t/upload-attachments-to-post/1009).

---

<div class="post-metadata">

**Author:** ![trichter](https://discourse.obspy.org/user_avatar/discourse.obspy.org/trichter/32/226_2.png) [@trichter](https://discourse.obspy.org/u/trichter)\
**Post date:** [July 28, 2020, 5:28pm UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/6 "2020-07-28T17:28:13Z")

</div>

Edit: Uploading waveform files should work now.

Also, please have a look at the `rfstats` function. It can calculate the slowness from station and event coordinates.

---

<div class="post-metadata">

**Author:** ![Sarenrenegade](https://discourse.obspy.org/letter_avatar_proxy/v4/letter/s/47e85d/32.png) [@Sarenrenegade](https://discourse.obspy.org/u/Sarenrenegade)\
**Post date:** [July 29, 2020, 7:32am UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/7 "2020-07-29T07:32:56Z")

</div>

It’s weird because it was working fine with spyder until now… Anyway is the slowness vp/vs? I used TauP once and I don’t remember entering any slowness parameter…

> **This is the list from conda list**
>
> - backcall 0.2.0 pyh9f0ad1d\_0 conda-forge - backports 1.0 py\_2 conda-forge - backports.functools\_lru\_cache 1.6.1 py\_0 conda-forge - blas 1.0 mkl - boost-cpp 1.72.0 h89d28cc\_2 conda-forge - brotlipy 0.7.0 py38h1e8a9f7\_1000 conda-forge - bzip2 1.0.8 hfa6e2cd\_2 conda-forge - ca-certificates 2020.6.20 hecda079\_0 conda-forge - cairo 1.16.0 hc79e3cf\_1005 conda-forge - cartopy 0.18.0 py38hde6099d\_1 conda-forge - certifi 2020.6.20 py38h32f6830\_0 conda-forge - cffi 1.14.1 py38hba49e27\_0 conda-forge - cfitsio 3.470 hbbe6aef\_6 conda-forge - chardet 3.0.4 py38h32f6830\_1006 conda-forge - clangdev 5.0.0 flang\_3 [flang] conda-forge - cloudpickle 1.5.0 py\_0 conda-forge - colorama 0.4.3 py\_0 conda-forge - cryptography 3.0 py38hba49e27\_0 conda-forge - curl 7.71.1 h4b64cdc\_3 conda-forge - cycler 0.10.0 py\_2 conda-forge - decorator 4.4.2 py\_0 conda-forge - expat 2.2.9 he025d50\_2 conda-forge - flang 5.0.0 he025d50\_20180525 conda-forge - flang\_win-64 5.0.0 20180525 conda-forge - fortran-compiler 1.1.1 he67e8c7\_0 conda-forge - freetype 2.10.2 hd328e21\_0 conda-forge - freexl 1.0.5 hd288d7e\_1002 conda-forge - future 0.18.2 py38h32f6830\_1 conda-forge - gdal 3.1.2 py38h5f218aa\_1 conda-forge - geographiclib 1.50 py\_0 conda-forge - geos 3.8.1 he025d50\_0 conda-forge - geotiff 1.6.0 h09e6dc1\_1 conda-forge - gettext 0.19.8.1 hb01d8f6\_1002 conda-forge - glib 2.65.0 he4de6d7\_0 conda-forge - h5py 2.10.0 nompi\_py38ha551744\_104 conda-forge - hdf4 4.2.13 hf8e6fe8\_1003 conda-forge - hdf5 1.10.6 nompi\_ha405e13\_100 conda-forge - icc\_rt 2019.0.0 h0cc432a\_1 - icu 67.1 h33f27b4\_0 conda-forge - idna 2.10 pyh9f0ad1d\_0 conda-forge - intel-openmp 2019.4 245 - ipykernel 5.3.4 py38h5ca1d4c\_0 conda-forge - ipython 7.16.1 py38h23f93f0\_0 conda-forge - ipython\_genutils 0.2.0 py\_1 conda-forge - jedi 0.17.2 py38h32f6830\_0 conda-forge - jpeg 9d he774522\_0 conda-forge - jupyter\_client 6.1.6 py\_0 conda-forge - jupyter\_core 4.6.3 py38h32f6830\_1 conda-forge - kealib 1.4.13 h3b59ab9\_1 conda-forge - kiwisolver 1.2.0 py38heaebd3c\_0 conda-forge - krb5 1.17.1 hc04afaa\_1 conda-forge - libblas 3.8.0 14\_mkl conda-forge - libcblas 3.8.0 14\_mkl conda-forge - libcurl 7.71.1 h4b64cdc\_3 conda-forge - libffi 3.2.1 h6538335\_1007 conda-forge - libflang 5.0.0 h6538335\_20180525 conda-forge - libgdal 3.1.2 h586bd2e\_1 conda-forge - libiconv 1.15 hfa6e2cd\_1006 conda-forge - libkml 1.3.0 h7e985d0\_1011 conda-forge - liblapack 3.8.0 14\_mkl conda-forge - libnetcdf 4.7.4 nompi\_h256d12c\_105 conda-forge - libpng 1.6.37 hfe6a214\_1 conda-forge - libpq 12.3 hd9aa61d\_0 conda-forge - libsodium 1.0.17 h2fa13f4\_0 conda-forge - libspatialite 4.3.0a h9ed2f40\_1039 conda-forge - libssh2 1.9.0 hb06d900\_4 conda-forge - libtiff 4.1.0 h885aae3\_6 conda-forge - libwebp-base 1.1.0 hfa6e2cd\_3 conda-forge - libxml2 2.9.10 h5d81f1c\_2 conda-forge - libxslt 1.1.33 h579f668\_1 conda-forge - lxml 4.5.2 py38he3d0fc9\_0 conda-forge - lz4-c 1.9.2 h62dcd97\_1 conda-forge - m2w64-expat 2.1.1 2 - m2w64-gcc-libgfortran 5.3.0 6 - m2w64-gcc-libs 5.3.0 7 - m2w64-gcc-libs-core 5.3.0 7 - m2w64-gettext 0.19.7 2 - m2w64-gmp 6.1.0 2 - m2w64-libiconv 1.14 6 - m2w64-libwinpthread-git 5.0.0.4634.697f757 2 - m2w64-xz 5.2.2 2 - matplotlib-base 3.3.0 py38hfb9ee82\_1 conda-forge - mkl 2019.4 245 - mkl-service 2.3.0 py38hfa6e2cd\_0 conda-forge - msys2-conda-epoch 20160418 1 - numpy 1.19.1 py38h72c728b\_0 conda-forge - obspy 1.2.2 py38h4b8e87e\_0 conda-forge - olefile 0.46 py\_0 conda-forge - openjpeg 2.3.1 h57dd2e7\_3 conda-forge - openmp 5.0.0 vc14\_0 conda-forge - openssl 1.1.1g he774522\_0 conda-forge - owslib 0.20.0 py\_0 conda-forge - parso 0.7.1 pyh9f0ad1d\_0 conda-forge - pcre 8.44 h6538335\_0 conda-forge - pickleshare 0.7.5 py38h32f6830\_1001 conda-forge - pillow 7.2.0 py38h7011068\_1 conda-forge - pip 20.1.1 py\_1 conda-forge - pixman 0.38.0 hfa6e2cd\_1003 conda-forge - poppler 0.89.0 h5d62644\_1 conda-forge - poppler-data 0.4.9 1 conda-forge - postgresql 12.3 he14cc48\_0 conda-forge - proj 7.1.0 h7d85306\_1 conda-forge - prompt-toolkit 3.0.5 py\_1 conda-forge - pycparser 2.20 pyh9f0ad1d\_2 conda-forge - pyepsg 0.4.0 py\_0 conda-forge - pygments 2.6.1 py\_0 conda-forge - pyopenssl 19.1.0 py\_1 conda-forge - pyparsing 2.4.7 pyh9f0ad1d\_0 conda-forge - pyproj 2.6.1.post1 py38h5a885fd\_1 conda-forge - pyreadline 2.1 py38\_1001 conda-forge - pyshp 2.1.0 py\_0 conda-forge - pysocks 1.7.1 py38h32f6830\_1 conda-forge - python 3.8.5 h5fd99cc\_1\_cpython conda-forge - python-dateutil 2.8.1 py\_0 conda-forge - python\_abi 3.8 1\_cp38 conda-forge - pytz 2020.1 pyh9f0ad1d\_0 conda-forge - pywin32 227 py38hfa6e2cd\_0 conda-forge - pyyaml 5.3.1 py38h9de7a3e\_0 conda-forge - pyzmq 19.0.1 py38h77b9d75\_0 conda-forge - requests 2.24.0 pyh9f0ad1d\_0 conda-forge - scipy 1.5.0 py38h9439919\_0 - setuptools 49.2.0 py38h32f6830\_0 conda-forge - shapely 1.7.0 py38hbf43935\_3 conda-forge - six 1.15.0 pyh9f0ad1d\_0 conda-forge - spyder-kernels 1.9.3 py38h32f6830\_0 conda-forge - sqlalchemy 1.3.18 py38h1e8a9f7\_0 conda-forge - sqlite 3.32.3 he774522\_1 conda-forge - tbb 2020.1 he980bc4\_0 conda-forge - tiledb 2.0.6 h0b90766\_0 conda-forge - tk 8.6.10 hfa6e2cd\_0 conda-forge - tornado 6.0.4 py38hfa6e2cd\_0 conda-forge - tqdm 4.48.0 pyh9f0ad1d\_0 conda-forge - traitlets 4.3.3 py38h32f6830\_1 conda-forge - urllib3 1.25.10 py\_0 conda-forge - vc 14.1 h869be7e\_1 conda-forge - vs2015\_runtime 14.16.27012 h30e32a0\_2 conda-forge - wcwidth 0.2.5 pyh9f0ad1d\_1 conda-forge - wheel 0.34.2 py\_1 conda-forge - win\_inet\_pton 1.1.0 py38\_0 conda-forge - wincertstore 0.2 py38\_1003 conda-forge - xerces-c 3.2.3 ha925a31\_1 conda-forge - xz 5.2.5 h62dcd97\_1 conda-forge - yaml 0.2.5 he774522\_0 conda-forge - zeromq 4.3.2 ha925a31\_3 conda-forge - zlib 1.2.11 h2fa13f4\_1006 conda-forge - zstd 1.4.5 h1f3a1b7\_2 conda-forge

The spyder kernels are installed… I’ve sent you the sac file via e-mail.

---

<div class="post-metadata">

**Author:** ![trichter](https://discourse.obspy.org/user_avatar/discourse.obspy.org/trichter/32/226_2.png) [@trichter](https://discourse.obspy.org/u/trichter)\
**Post date:** [July 29, 2020, 8:32am UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/8 "2020-07-29T08:32:12Z")

</div>

Hi,

I do not see `rf` in the list of installed packages.

Everything does nicely work with your provided file. You just have to calculate the slowness with the `rfstats` function:

```py
from rf import read_rf, rfstats
s = read_rf('ev1.SAC')
rfstats(s)
s.ppoints(50)

```

Please take some time and find out what this slowness is about. It’s not the vp/vs ratio, but the ray parameter. If you have no resource at hand, in the rf doc you will find a link to a dissertation with some information about receiver functions.

---

<div class="post-metadata">

**Author:** ![Sarenrenegade](https://discourse.obspy.org/letter_avatar_proxy/v4/letter/s/47e85d/32.png) [@Sarenrenegade](https://discourse.obspy.org/u/Sarenrenegade)\
**Post date:** [July 29, 2020, 9:07am UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/9 "2020-07-29T09:07:32Z")

</div>

OK, you were right, I reinstalled and now it works! Thank you so much for your help😀! Just a quick question, is it possible to make loop in order to have all the events done at the same time?

---

<div class="post-metadata">

**Author:** ![trichter](https://discourse.obspy.org/user_avatar/discourse.obspy.org/trichter/32/226_2.png) [@trichter](https://discourse.obspy.org/u/trichter)\
**Post date:** [July 29, 2020, 9:50am UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/10 "2020-07-29T09:50:15Z")

</div>

Sure, that is possible. You can also load everything into one stream. The code block above works also for a stream of multiple traces.

---

<div class="post-metadata">

**Author:** ![Sarenrenegade](https://discourse.obspy.org/letter_avatar_proxy/v4/letter/s/47e85d/32.png) [@Sarenrenegade](https://discourse.obspy.org/u/Sarenrenegade)\
**Post date:** [July 29, 2020, 12:46pm UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/11 "2020-07-29T12:46:27Z")

</div>

Sorry to bother you again but I tried to put a pathname to read all the sac files but I get an error “permission denied”. I tried to find a way to join my sac files into one through ObsPy but I can’t find it either… I’m a little lost…

---

<div class="post-metadata">

**Author:** ![trichter](https://discourse.obspy.org/user_avatar/discourse.obspy.org/trichter/32/226_2.png) [@trichter](https://discourse.obspy.org/u/trichter)\
**Post date:** [July 30, 2020, 7:10am UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/12 "2020-07-30T07:10:58Z")

</div>

Something like `read_rf('ev1.SAC') + read_rf('ev2.SAC')` or using a glob expression with `read_rf('*.SAC')` should work.

---

<div class="post-metadata">

**Author:** ![Sarenrenegade](https://discourse.obspy.org/letter_avatar_proxy/v4/letter/s/47e85d/32.png) [@Sarenrenegade](https://discourse.obspy.org/u/Sarenrenegade)\
**Post date:** [July 30, 2020, 10:07am UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/13 "2020-07-30T10:07:02Z")

</div>

OK thank you very much for your patience and assistance 😊

---

<div class="post-metadata">

**Author:** ![Sarenrenegade](https://discourse.obspy.org/letter_avatar_proxy/v4/letter/s/47e85d/32.png) [@Sarenrenegade](https://discourse.obspy.org/u/Sarenrenegade)\
**Post date:** [July 31, 2020, 8:24am UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/14 "2020-07-31T08:24:59Z")

</div>

Hi! it’s me again: I tried to import all my files with glob using two methods but none of them seems to be working. One returns only 9 piercing points out of  
77 and with the wrong coordinates and the other returns an empty array… Here’s the codes for both methods:  
method A:

```python
e=[]
from rf import read_rf, rfstats
import os, glob
folder_path='Users\Maureen\Documents\M1 Stage\Python\LN14'
for filename in glob.glob(os.path.join(folder_path,'*.SAC')):
    with open(filename, 'r') as f:
        s =read_rf()
        rfstats(s)
        e.append(s.ppoints(50,'P'))
print(e)

return : []

```

method B:

```python
from rf import read_rf, rfstats
import os, glob
for file in glob.glob('*.SAC'):
    s= read_rf()
    rfstats(s)
    s.ppoints(50,'P')
    print(s.ppoints(50,'P'))

return: [[-20.82703869 -69.64815651]
[-20.82703869 -69.64815651]
[-20.82703869 -69.64815651]
[-21.26771754 -69.34484486]
[-21.26771754 -69.34484486]
[-21.26771754 -69.34484486]
[-20.77253233 -69.6304343]
[-20.77253233 -69.6304343]
[-20.77253233 -69.6304343]]

```

I know those coordinates are wrong because the station is located in Tanzania and those points are not… I’m leaning towards a problem using glob: the program works for one event… Do you know if I can use an ascii file or a .txt file or use pandas? I built a txt file with pandas that contains backazimut and the distance between the event and the station, and I seem to remember that TauP was capable of finding the piercing points with those parameters…

---

<div class="post-metadata">

**Author:** ![megies](https://discourse.obspy.org/user_avatar/discourse.obspy.org/megies/32/9_2.png) [@megies](https://discourse.obspy.org/u/megies)\
**Post date:** [July 31, 2020, 8:45am UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/15 "2020-07-31T08:45:00Z")

</div>

@Sarenrenegade you can see [here](https://commonmark.org/help/) for how to properly format code blocks (and other things). 🙂  
Edited your above post. 😉

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<div class="post-metadata">

**Author:** ![trichter](https://discourse.obspy.org/user_avatar/discourse.obspy.org/trichter/32/226_2.png) [@trichter](https://discourse.obspy.org/u/trichter)\
**Post date:** [July 31, 2020, 11:33am UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/16 "2020-07-31T11:33:23Z")

</div>

You are not using the variable `f` in method A and `file` in method B.

---

<div class="post-metadata">

**Author:** ![Sarenrenegade](https://discourse.obspy.org/letter_avatar_proxy/v4/letter/s/47e85d/32.png) [@Sarenrenegade](https://discourse.obspy.org/u/Sarenrenegade)\
**Post date:** [July 31, 2020, 3:24pm UTC](https://discourse.obspy.org/t/slowness-error-while-using-stream-ppoints/1008/17 "2020-07-31T15:24:51Z")

</div>

Even when I use file and filename it doesn’t work… It’s problem with the pathname… The quickest solution was to work in the directory😊  
Thanks for your help 😀