Home / ubuntu / Questions / 1195524
Accepted
chess_freak
Asked: 2019-12-12 13:00:38 +0800 CST

How to manipulate specific fields?

  • 772

I have a csv file. Its line numbers are max 25.

Headings are time(UTC)(1st field), latitude(2nd field), longitude(3rd field), depth (4th field), mag(5th field), place (14th field) and so forth

Sample data

2019-12-10T21:58:28.816Z 35.488 26.4157 57.32 5.4 35km NNE of Palaikastron, Greece


2019-12-11T11:54:27.670Z 18.6158 -67.2838 85 2.85 23km NW of San Antonio, Puerto Rico

First, I want to inset heading, including built-in variable fieldwith. Second, I want to convert time(utc) to utc+03:00 and divided into date and time of headings and to change its date format. Third, I want to extract matches between 'of' word and comma before country name for 14th field.

Desired output as headings:

Date Time Latitude Longitude Depth Mag Place

Desired output:

11.12.2019 00:58:28 35.488 26.4157 57.32 5.4 Palaikastron


11.12.2019 14:54:27 18.6158 -67.2838 85 2.85 San Antonio

time,latitude,longitude,depth,mag,magType,nst,gap,dmin,rms,net,id,updated,place,type,horizontalError,depthError,magError,magNst,status,locationSource,magSource
2019-12-06T13:04:46.931Z,-15.2838,-175.1193,10,6,mww,,50,3.512,0.81,us,us60006n19,2019-12-07T13:11:48.228Z,"164km WNW of Hihifo, Tonga",earthquake,8.4,1.9,0.08,15,reviewed,us,us
2019-12-04T20:10:03.614Z,-19.0515,169.5628,266,6,mww,,21,2.812,0.82,us,us60006m2j,2019-12-05T23:44:01.300Z,"63km NNE of Isangel, Vanuatu",earthquake,7.6,1.9,0.037,71,reviewed,us,us
2019-12-03T08:46:36.374Z,-18.5597,-70.6504,32.44,6,mww,,112,0.31,1.4,us,us70006fh7,2019-12-05T08:07:29.617Z,"37km WSW of Arica, Chile",earthquake,6.2,7.8,0.069,20,reviewed,us,us
2019-12-02T05:01:54.693Z,51.3218,-178.2425,27.33,6,mww,,104,0.862,0.97,us,us70006f6d,2019-12-07T02:09:55.119Z,"60km E of Amatignak Island, Alaska",earthquake,6.7,4.2,0.066,22,reviewed,us,us
2019-11-27T07:23:42.552Z,35.7272,23.2673,71.76,6,mww,,23,1.394,1.16,us,us70006dlt,2019-12-03T23:18:27.456Z,"41km NW of Platanos, Greece",earthquake,5.8,5.4,0.046,46,reviewed,us,us
2019-11-26T02:54:12.594Z,41.5112,19.5151,20,6.4,mww,,17,0.937,0.58,us,us70006d0m,2019-12-09T15:46:11.689Z,"16km WSW of Mamurras, Albania",earthquake,3.5,1.8,0.037,72,reviewed,us,us
2019-11-24T00:54:01.052Z,51.3809,-175.5108,20,6.3,mww,,22,0.658,0.95,us,us70006cb6,2019-12-10T01:04:03.731Z,"96km SE of Adak, Alaska",earthquake,3.9,1.8,0.05,38,reviewed,us,us
2019-11-23T12:11:16.261Z,1.6286,132.7854,10,6.1,mww,,38,4.549,1.1,us,us70006c6w,2019-11-25T21:00:33.040Z,"Papua region, Indonesia",earthquake,7.8,1.8,0.061,26,reviewed,us,us
2019-11-20T23:50:43.955Z,19.4533,101.3558,10,6.2,mww,,15,2.366,0.62,us,us70006ara,2019-12-04T05:52:37.313Z,"32km ESE of Chaloem Phra Kiat, Thailand",earthquake,6.4,1.7,0.049,40,reviewed,us,us

If I can succeed one thing, I don't do others. It is challenge for me. Guide me, please. One the one hand, have difficulty to understand to use awk for it. On the other hand, awk time functions are very useful. I am so confused now. Whatever I've tried, I don't make good at.

command-line bash date awk

2 Answers

  1. First, you'll need to pre-process the CSV input to handle the embedded comma better. Then break down the AWK into functional chunks.

    $ cat preprocess.sed
#!/bin/sed -f
:start   # loop back to here
/"/{  # for any line that has a double quote
  h   # copy to the hold buffer
  s/[^"]*"\([^"]*\).*/\1/  # what is between the first pair of dquotes
  s/,/@@/g    # replace comma with '@@'
  G   # append the hold buffer to the pattern buffer
      # so we get what was in dqoutes followed by a newline followed by the
      # original line
  s/\(.*\)\n\([^"]*\)"\([^"]*\)"\(.*\)/\2\1\4/
      # replace the unquoted part with what was there
  t start   # go back to 'start'
}

    This will replace the ".*,.*" with .*@@.*, which will make it easier for AWK.

    To change just the date to a new timezone, replace the first line:

    $ cat change_date.sh
#!/bin/sh
userTZ="${1:-UTC+3}"
sed 's/,/ /' |
    while read datestr rest; do
        if [ "${datestr}" = time ]; then
            newdate="${datestr}"
        else
            newdate=$(TZ=${userTZ} date -d "${datestr}" "+%d %m %Y %H:%M:%S")
        fi
        echo "${newdate}:${rest}"

    done

    The AWK script would look like:

    $ cat reformat.awk
#!/bin/awk  -f
BEGIN {IFS=","}  # comma separated fields
NR==1 {print; next;}  # print the header and do nothing more with it
{   # get just the "town" from the place field
    sub(/.* of /,"",$14)  # strip up to the " of "
    sub(/@@ .*/,"",$14)   # strip after the embedded comma (now '@@')
}
{
    printf("%s %8.3f %8.3f %8.3fs %8.3f %s\n", $1, $2, $3, $4, $5, $14)
}

    Make sure both are executable and run preprocess.sed sample.csv | change_date.sh | reformat.awk

    Or on one line:

    sed ':start;/"/{;h;s/[^"]*"\([^"]*\).*/\1/;s/,/@@/g;G;s/\(.*\)\n\([^"]*\)"\([^"]*\)"\(.*\)/\2\1\4/;t start;};s/,/ /' test.csv | while read datestr rest; do if [ "$datestr" = "time" ]; then newdate="${datestr}"; else newdate=$(TZ=UTC+3 date -d "$datestr" "+%d %m %Y %H:%M:%S"); fi; echo "${newdate},${rest}"; done | awk -F, 'NR==1 {print;next} {sub(/.* of /,"",$14);sub(/@@ .*/,"",$14)} {printf("%s %8.3f %8.3f %8.3fs %8.3f %s\n", $1, $2, $3, $4, $5, $14)}'
    • 2
  2. Best Answer

    Although learning awk is an admirable goal, it has no built-in mechanism for parsing true CSV files (in particular, fields that may contain escaped or quoted delimiters) - and the time functions are GNU-specific and not portable.

    For these reasons you may want to consider using Perl (with its Text::CSV module), Python - or my current favorite for this kind of thing, Miller. As well as providing true CSV parsing, these also provide a proper strptime function whereas even with GNU awk's mktime you need to manually parse and assemble the datespec argument.

    In Miller for example, you could do the following:

    mlr --csv \
  put -S '
    s = strptime($time,"%Y-%m-%dT%H:%M:%SZ") + 3*3600; 
    $date = strftime(s,"%d.%m.%Y"); 
    $time = strftime(s,"%H:%M:%S"); 
    $place =~ "(.* of |)([^,]*),(.*)$" { $place = "\2" }
  ' then cut -o -f date,time,latitude,longitude,depth,mag,place input.csv

    If you want whitespace separated output columns, change --csv to --icsv --opprint ("pretty printed" tabular output - with headers) or --icsv --onidx (simple space-separated output).

    Ex.

    $ mlr --icsv --opprint   put -S '
    s = strptime($time,"%Y-%m-%dT%H:%M:%SZ") + 3*3600; 
    $date = strftime(s,"%d.%m.%Y"); 
    $time = strftime(s,"%H:%M:%S"); 
    $place =~ "(.* of |)([^,]*),(.*)$" { $place = "\2" }
  ' then cut -o -f date,time,latitude,longitude,depth,mag,place input.csv
date       time     latitude longitude depth mag place
06.12.2019 16:04:46 -15.2838 -175.1193 10    6   Hihifo
04.12.2019 23:10:03 -19.0515 169.5628  266   6   Isangel
03.12.2019 11:46:36 -18.5597 -70.6504  32.44 6   Arica
02.12.2019 08:01:54 51.3218  -178.2425 27.33 6   Amatignak Island
27.11.2019 10:23:42 35.7272  23.2673   71.76 6   Platanos
26.11.2019 05:54:12 41.5112  19.5151   20    6.4 Mamurras
24.11.2019 03:54:01 51.3809  -175.5108 20    6.3 Adak
23.11.2019 15:11:16 1.6286   132.7854  10    6.1 Papua region
21.11.2019 02:50:43 19.4533  101.3558  10    6.2 Chaloem Phra Kiat

    Miller is available from the Ubuntu universe repository.

    • 2