[R] dealing with a messy dataset

[jim holtman]

You should be able to use that header information to create the
correct parameters to the read_fwf function to read in the data.

Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.


On Thu, Oct 5, 2017 at 11:02 AM, jean-philippe
<jeanphilippe.fontaine at gssi.infn.it> wrote:
> dear Jim,
>
> Thanks for your reply and your proposition.
>
> I forgot to provide the header of the dataframe, here it is:
> ================================================================================
> Byte-by-byte Description of file: lvg_table2.dat
> --------------------------------------------------------------------------------
>    Bytes Format Units       Label   Explanations
> --------------------------------------------------------------------------------
>    1- 18 A18    ---         Name    Galaxy name in well-known catalogs
>   20- 21 I2     h           RAh     Hour of Right Ascension (J2000)
>   22- 23 I2     min         RAm     Minute of Right Ascension (J2000)
>   24- 27 F4.1   s           RAs     Second of Right Ascension (J2000)
>       28 A1     ---         DE-     Sign of the Declination (J2000)
>   29- 30 I2     deg         DEd     Degree of Declination (J2000)
>   31- 32 I2     arcmin      DEm     Arcminute of Declination (J2000)
>   33- 34 I2     arcsec      DEs     Arcsecond of Declination (J2000)
>   36- 40 F5.2   kpc         a26     ? Major linear diameter (1)
>   42- 43 I2     deg         inc     ? Inclination
>   45- 47 I3     km/s        Vm      ? Amplitude of rotational velocity (2)
>   49- 52 F4.2   mag         AB      ? Internal B band extinction (3)
>   54- 58 F5.1   mag         BMag    ? Absolute B band magnitude (4)
>   60- 63 F4.1   mag/arcsec2 SBB     ? Average B band surface brightness (5)
>   65- 69 F5.2   [solLum]    logKLum ? Log K_S_ band luminosity (6)
>   71- 75 F5.2   [solMass]   logM26  ? Log mass within Holmberg radius (7)
>       77 A1     ---       l_logMHI  Limit flag on logMHI
>   78- 82 F5.2   [solMass]   logMHI  ? Log hydrogen mass (8)
>   84- 87 I4     km/s        VLG     ? Radial velocity (9)
>   89- 92 F4.1   ---         Theta1  ? Tidal index (10)
>   94-116 A23    ---         MD      Main disturber name (11)
>  118-121 F4.1   ---         Theta5  ? Another tidal index (12)
>  123-127 F5.2   [-]         Thetaj  ? Log K band luminosity density (13)
> --------------------------------------------------------------------------------
>
> The idea for me is to select only the galaxy name and the logMHI values for
> these galaxies, so quite a simple job when the dataset is tidy enough. I was
> thinking as usual to use select from dplyr.
> That is why I was just asking how to read this kind of files which, for me
> so far, are uncommon.
>
> Doing what you propose, it formats most of the columns correctly except few
> ones, I will see how I can change some width to get it correctly:
>
>           X1              X2    X3    X4    X5    X6    X7    X8 X9    X10
> X11   X12   X13   X14          X15   X16     X17
>        (chr)           (chr) (dbl) (int) (dbl) (dbl) (chr) (dbl) (chr)
> (chr) (int) (chr) (chr) (chr)        (chr) (dbl)   (chr)
> 1   UGC12894 000022.5+392944  2.78    33    21     0 -13.3  25.2 7.5 8  8.1
> 7   7.9 2  61 9 -1.    3 NGC7640    -1 0  0.12
> 2        WLM 000158.1-152740  3.25    90    22     0 -14.1 24.8 7.7 0 8.2
> 7   7.8 4  -1 6  0. 0 MESSIER031     0 2  1.75
> 3  And XVIII 000214.5+450520  0.69    17     9     0  -8.7  26.8 6.4 4  6.7
> 8 < 6.6 5  -4 4  0. 5 MESSIER031     0 6  1.54
> 4  PAndAS-03 000356.4+405319  0.10    17    NA     0  -3.6  27.8 4.3      8
> NA    NA    NA    2. 8 MESSIER031     2 8  1.75
> 5  PAndAS-04 000442.9+472142  0.05    22    NA     0  -6.6  23.1 5.5      9
> NA    NA   -10 8  2. 5 MESSIER031     2 5  1.75
> 6  PAndAS-05 000524.1+435535  0.06    31    NA     0  -4.5  25.6 4.7      5
> NA    NA    10 3  2. 8 MESSIER031     2 8  1.75
> 7 ESO409-015 000531.8-280553  3.00    78    23     0 -14.6  24.1 8.1 0  8.2
> 5   8.1 0  76 9 -2.    0 NGC0024    -1 5 -2.05
> 8  AGC748778 000634.4+153039 0.61 70     3     0 -10.4  24.9 6.3 9  5.7
> 0   6.6 4  48 6 -1.    9 NGC0253    -1 5 -2.72
> 9     And XX 000730.7+350756  0.20    33     5     0  -5.8  27.1 5.2 6  5.7
> 0    NA   -18 2  2. 4 MESSIER031     2 4  1.75
>
>
> Cheers, thanks again
>
>
> Jean-Philippe
> On 05/10/2017 16:49, jim holtman wrote:
>>
>> start <- c(1, 20, 35, 41, 44, 48, 53, 59, 64, 69, 75, 77, 82, 87,
>>      +            92, 114, 121, 127)
>>      > read_fwf(input, fwf_widths(diff(start)))
>
>
> --
> Jean-Philippe Fontaine
> PhD Student in Astroparticle Physics,
> Gran Sasso Science Institute (GSSI),
> Viale Francesco Crispi 7,
> 67100 L'Aquila, Italy
> Mobile: +393487128593, +33615653774
>