CODEWITHSUNDEEP
pythondataframeastropyastronomy
Ambica Govind
Ambica Govind

Reputation: 168

How to keep certain rows from ASCII Table using Astropy

I am working with this ASCII Dataset wherein I need to remove certain rows. I am using ASTROPY:

from astropy.io import ascii

gw170817 = ascii.read('gw170817_afterglow_data_full.txt')

Table length=215

DateUT  T   Telescope   Freq    FluxD   FluxDErr
str24   float64 str10   float64 str7    float64
2017-Aug-18.10  0.57    VLA 9700000000.0    <144    --
2017-Aug-18.1   0.6 Swift   2.41e+17    <7.8e-3 --
2017-Aug-18.21  0.68    ATCA    8500000000.0    <120    --
2017-Aug-18.21  0.68    ATCA    10500000000.0   <150    --
2017-Aug-18.2   0.7 NuSTAR  1.2e+18 <7.3e-4 --
2017-Aug-18.46  0.93    uGMRT   610000000.0 <195    --
2017-Aug-18.5   1.0 Swift   2.41e+17    <7.5e-2 --
2017-Aug-18.6   1.1 Swift   2.41e+17    <5.0e-3 --
2017-Aug-18.95  1.43    ALMA    339000000000.0  <126    --
2017-Aug-18.97  1.44    VLA 10000000000.0   <13.8   --
... ... ... ... ... ...
2019-Sep-21--27 767.0   VLA 3000000000.0    4.90e0  1.8
2020-Mar-13 938.0   Chandra 2.41e+17    1.30e-4 5.23e-05
2020-Nov-14 1185.0  ATCA    2100000000.0    <51 --
2021-Feb-20 1283.0  ATCA    2100000000.0    <75 --
2021-Apr-06 1328.0  ATCA    2100000000.0    <54 --
2021-Apr-08 1330.0  ATCA    5500000000.0    <44 --
2021-Apr-08 1330.0  ATCA    9000000000.0    <31 --
2020-Dec-09--2021-Jan-27    1231.0  Chandra 2.41e+17    1.70e-4 4.7e-05
2020-Sep-19--2021-Feb-08    1228.0  VLA 3000000000.0    2.86e0  0.99
2020-Feb-10 1273.0  VLA 15000000000.0   <5.7    --

I want to keep only rows that satisfy gw170817['Freq']==3000000000 and gw170817['Telescope']=='VLA'. Please help me out.

Upvotes: 0

Views: 103

Answers (1)

Manon
Manon

Reputation: 124

With an astropy.table.table.Table object, you can generate a mask object (see their doc here):

(gw170817['Freq']==3000000000) & (gw170817['Telescope']=='VLA')

and then apply it to your initial table to get what you want:

gw170817[(gw170817['Freq']==3000000000) & (gw170817['Telescope']=='VLA')]

Upvotes: 0

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