Hi Richard,
That was just an example, to show that, for that particular string of
binary numbers, the code works as expected. That is absolutely no related
to the dataset I provided. If I try the function on the dataset, I get
values well over the latitude and longitude boundaries (which should range
from -90 to + 90, and -180 to +180).
Regards,
Paul
El vie., 24 ene. 2020 a las 12:23, Richard M. Heiberger (<r...@temple.edu>)
escribió:
> You show the example
>
> > fun("10110010")
> [1] -78
>
> as satisfactory. Where in your posted data set do you find the input
> string "10110010"?
>
> Please post a set of relevant input strings, and the answers you want from
> them.
> The rest of the columns are not helpful for this specific exercise.
>
> On Fri, Jan 24, 2020 at 11:34 AM Paul Bernal <paulberna...@gmail.com>
> wrote:
> >
> > Dear friend Rui,
> >
> > Hope you are doing great. Firstly, I want to thank you for your super
> > valuable and kind support of always. As I mentioned in earlier e-mails, I
> > am trying to decode AIS type messages, and the only ones I am having a
> real
> > hard time with, is with latitude and longitude.
> >
> > I tried the function you provided me in one of your replies, and it works
> > well with the examples you provided, but in other cases it doesn´t.
> >
> > The messages I am trying to decode are in the 6th column of the data. I
> > will provide you with a small sample first, and then the complete dataset
> > (which has 100 rows). This is the small sample:
> >
> > > head(dat)
> > ...1 ...2 ...3 ...4 ...5 ...6 ...7 ...8
> > ...9 ...10 ...11 ...12 ...13
> > 1 !AIVDM 1 1 NA A 15?f5H?P00rCQat5:Oah0?wn2@S6 0*54
> 1485907200
> > <NA> NA NA NA <NA>
> > 2 !AIVDM 1 1 NA A 1349B:3000rCtrn553aR@JH02PRp 0*39
> 1485907200
> > <NA> NA NA NA <NA>
> > 3 !AIVDM 1 1 NA A D03Iuph1TNfp4dv9J<`N000 2*0D 1485907200
> > <NA> NA NA NA <NA>
> > 4 !AIVDM 1 1 NA A D03Iu6QGLN01MdN01StN000 2*43 1485907200
> > <NA> NA NA NA <NA>
> > 5 !AIVDO 1 1 NA <NA> B;s@N9h00>TtPEQAslh03wuUwP06 0*29
> 1485907200
> > <NA> NA NA NA <NA>
> > 6 !AIVDM 1 1 NA A 15A@av3P00rClHn53<I8M?v02<2B 0*2D
> 1485907200
> > <NA> NA NA NA <NA>
> >
> > It is worth mentioning that each row of the 6th column provides several
> > information about maritime vessels, like speed over ground, latitude,
> > longitude, vessel ID, etc. I am only concerned with latitude and
> longitude
> > since those are the only two fields I have not been able to decode
> > successfully. Also, I am working on R version 3.6.2 for windows 64-bit
> OS.
> >
> > The messages to decode are of the following format:
> > 15?f5H?P00rCQat5:Oah0?wn2@S6, 1349B:3000rCtrn553aR@JH02PRp, etc.
> >
> > Now, here is the complete dataset:
> >
> > > dput(dat)
> > structure(list(...1 = c("!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM",
> > "!AIVDO", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM",
> > "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDO", "!AIVDM", "!AIVDM",
> > "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM",
> > "!AIVDO", "!AIVDM", "$GPRMC", "!AIVDM", "!AIVDM", "!AIVDM", "$GPGBS",
> > "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDO", "!AIVDM", "!AIVDM", "!AIVDM",
> > "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDO", "!AIVDM", "!AIVDM",
> > "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDO", "!AIVDM",
> > "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM",
> > "!AIVDM", "!AIVDO", "$GPRMC", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM",
> > "!AIVDM", "$GPGBS", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDO", "!AIVDM",
> > "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDO", "!AIVDM", "!AIVDM",
> > "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDO", "!AIVDM",
> > "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM", "!AIVDM",
> > "!AIVDM", "$GPRMC", "!AIVDO", "!AIVDM", "!AIVDM"), ...2 = c(1,
> > 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
> > 1, 1, 1, 1, 1, 50002, 1, 2, 2, 50002, 1, 1, 1, 1, 1, 1, 1, 1,
> > 1, 2, 2, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2,
> > 1, 50006, 1, 1, 1, 1, 1, 50006, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1,
> > 1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 50010, 1,
> > 1, 1), ...3 = c("1", "1", "1", "1", "1", "1", "1", "1", "1",
> > "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1",
> > "1", "1", "1", "1", "1", "A", "1", "1", "2", "1.3", "1", "1",
> > "1", "1", "1", "1", "1", "1", "1", "1", "2", "1", "1", "1", "1",
> > "1", "1", "1", "2", "1", "1", "1", "1", "1", "1", "1", "1", "1",
> > "2", "1", "A", "1", "1", "1", "1", "1", "1.3999999999999999",
> > "1", "2", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1", "1",
> > "1", "1", "2", "1", "1", "1", "1", "2", "1", "1", "1", "1", "1",
> > "1", "A", "1", "1", "1"), ...4 = c(NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, 856.96783, NA, 7, 7, 1.5, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, 8, 8, NA, NA, NA, NA, NA, NA, 9, 9, NA, NA, NA,
> > NA, NA, NA, NA, NA, 0, 0, NA, 856.96805, NA, NA, NA, NA, NA,
> > 1.5, 1, 1, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 2,
> > 2, NA, NA, NA, 3, 3, NA, NA, NA, NA, NA, NA, 856.96827, NA, NA,
> > NA), ...5 = c("A", "A", "A", "A", NA, "A", "A", "B", "B", "A",
> > "A", "A", "A", "B", "B", NA, "B", "A", "B", "A", "B", "B", "A",
> > "B", "A", NA, "B", "N", "B", "A", "A", "3.2000000000000002",
> > "B", "A", "A", NA, "A", "A", "A", "A", "B", "A", "A", NA, "B",
> > "A", "A", "A", "A", "A", "A", NA, "A", "A", "A", "B", "B", "B",
> > "B", "A", "A", NA, "N", "A", "A", "B", "B", "B", "3.2999999999999998",
> > "B", "B", "B", NA, "B", "B", "A", "B", "B", NA, "B", "B", "A",
> > "A", "B", "B", "A", NA, "B", "B", "B", "A", "A", "A", "A", "A",
> > "B", "N", NA, "B", "B"), ...6 = c("15?f5H?P00rCQat5:Oah0?wn2@S6",
> > "1349B:3000rCtrn553aR@JH02PRp", "D03Iuph1TNfp4dv9J<`N000",
> > "D03Iu6QGLN01MdN01StN000",
> > "B;s@N9h00>TtPEQAslh03wuUwP06", "15A@av3P00rClHn53<I8M?v02<2B",
> > "1000Fo@P01rCuG<56bnkN?v004`0", "15QK900001JCq=d54l?5J0op0l4e",
> > "15@eD@8000rC`bl59kW`mFn004`0", "15QIK`0P00rC`Sb59jFUUgv02<1g",
> > "403Iupiv4PU00rC9065>=fW00H0I", "403Iu6Qv4PU00rCk0d57rwW00<2g",
> > "H5?AU:4U653hhhi8@lkihP000000", "15TGcJ0002rD<>p55FgmI@Ul0H0S",
> > "15Aq00?P00rC`a`59mFeogv004`0", "B;s@N9h00>TtPF1Asll03wP5wP06",
> > "13P;K8@Oh1rCfgp58=ec1bD22<4J", "139NL4000LrCc8j59FEED4@000S<",
> > "403Iupiv4PU00rC9065>=fW00H0j", "39NS@m11@1rCrb:53:E<v0j3R000",
> > "403Iu6Qv4PU01rCk0d57rwW00<2g", "15PvE@0002rCi7R57pokCT:424`0",
> > "15TgVb0000rCgVd57oFc31R42L46", "15PoOh0001rCgbt58CwUaBD004`0",
> > "A03IupkAC4:dH0v90>@P1cF6nud@NrP5wH5T", "B;s@N9h00>TtPF1Asll03wPUwP06",
> > "15E=q08P00JCrnR52cb>4?v200Sw", "7933.8836099999999",
> > "15>uP00P00rC`U:59im;H?v22@1D",
> > "54aMBf02:9M`?IDOH018DL4j085T000000000016>`Q8>4Oc0?@lRDm3hPC0",
> > "3", NA, "1018lEWP?w<tSF0l4Q@>4?wp0W3h", "15BkV00P00rCQBf5:Q5JQOv42D1o",
> > "35QN<D1000rCr5l53esbgPR20000", "B;s@N9h00>TtPF1Aslp03wQ5wP06",
> > "34`odN1000rD1V2537=dfPJ60000", "15>nNj0000rCT<@5::qUpkt604`0",
> > "15UHOn9P00rCQ`D5:OcTkgv80<4:", "35A=Rh1001rD;s454vSTuP`40000",
> > "15U?B00000rCgb>58DFJfRl620RT",
> "55B7iD42CSGC<H`WF20L5>1=@5:222222222221@G
> > @W9K4Oi0D@PC0ShK40C",
> > "PC@H8888880", "B;s@N9h00>TtPFQAslt03wQUwP06",
> > "15De7F?P00JCr5r5517v4?v80h2P",
> > "15U@cn0000rCgU>57oPLGiT:2D4D", "137g`F8007rCaIj59Tc5Dl@800SN",
> > "15?7P`0P00rD1S453KSlj?v824`0", "15?mqH?P00rCek458rkEN?v:00S4",
> > "55R4:002?H<`Q3S7GR1<lUB0@4pF22222222220l000004p60;0E7kBE8888",
> > "88888888880", "B;s@N9h00>TtPFQAslt03wR5wP06",
> > "15E:BR0P00rCgaT58DdJUwv82H34",
> > "15AIw`0P0GrCcO859DO5Ogv:0T`0", "14aMBf000wrCKKN5:sdU0Sv<083C",
> > "1819?@H001rC9TB5=bppM9<82D0T", "13M@Hk00jSJD@RD4s=qG1mT80@3J",
> > "15BI>P0001rCgUD58DRalRj:00S5", "100000?P00JCkt:583J=r?v:283Q",
> > "A03IupkAC4:dH0N90C9p0goOwj<Cw`P05A7vnh081wqU05DFwAKw<0?va@1>",
> > "1gu00CLLwfh2@Asw9@1<", "B;s@N9h00>TtPFQAsm003wRUwP06",
> > "7933.8835099999997",
> > "18K1kH000FrCSMt5:@;m>l8>0<4J", "19NSFKh000JCTeH5:7g1LT8:0`3g",
> > "15E=m60000rC`W459k28Wnd:083h", "1:u0KOh001rCq5P529qqubqh2@3n",
> > "13P>4mhw1CrCi5H57aK5WlN>0<4F", NA,
> > "A03IupkAC4:dH0N90D=p0goP02<Cw``05A7vnwt81wqVwUDFwAOt<0?vah1>",
> > "1gu103LLwfl1@Asw9P1<", "14S8@n001LrD?bH53iGe1rN>0@49",
> > "B;s@N9h00>TtPG1Asm403wSUwP06",
> >
> > "15E:N@0000rCgOd57p45bW><0<2H", "15@EA<0P01JCo8l53=BFgwv@0D47",
> > "10007NgP00rCQGV5:Pa=?gv>2<1H", "15TILd?P00JCm4l53`D>4?v>0L1m",
> > "19NSG<h003rCi@:57pmUkAB<0<1v", "B;s@N9h00>TtPG1Asm403wT5wP06",
> > "15Q69@8000rCiDr57n`bp@tB2<4R", "15QtF00000rCafD59P?VJ9p<0H52",
> > "15QCl@?P?w<tSF0l4Q@>4?wp0@5:", "15QDCP0P?w<tSF0l4Q@>4?wp0D1G",
> > "803Iu6PF15REPH3@Dh000000000002c88I2P0002IrbQ0@40TW`800000000",
> > "HGp0772K07N4d1;0Pf71r0aj19RVmR19RVuR19RW5R19RW;t91Cjp31000C4",
> > "15D8Gj0P00rCThP5:6T=2Ov>0@5H", "B;s@N9h00>TtPG1Asm803wTUwP06",
> > "15ATk20000rCnrv53N6;gPr>085R",
> > "55AP::02@VAlQ3G;7:1<lUB0MD4@DhuE0F22220l0`G465k90<PlRDm3hPC8",
> >
> > "88888888880", "15?lSL?P00JCQWD5:OpP0?vB24`0",
> > "15BW=20P00JCrvH54t=an?vB00Sg",
> > "13P;K8@001rCfgr58=f;QbFD2D4G", "A03IupkAC4:dH0v90FtP1cF6nud@NrP5wH5T",
> > "85E:BR0F0P0000000000032jS2P000000DE7P3A00h0",
> "1349B:3000rCtrn553aR@JHD2d4O",
> >
> > "7933.8835099999997", "B;s@N9h00>TtPFQAsm803wU5wP06",
> > "15B3Sj0000rC9RD5=mOh40jB20SU",
> > "15TgVb0000rCgVb57oFc;ARF2@67"), ...7 = c("0*54", "0*39", "2*0D",
> > "2*43", "0*29", "0*2D", "0*27", "0*1D", "0*26", "0*48", "0*4B",
> > "0*3A", "0*34", "0*3A", "0*76", "0*0B", "0*4A", "0*72", "0*6B",
> > "0*4E", "0*38", "0*04", "0*11", "0*17", "0*18", "0*6B", "0*64",
> > "W", "0*53", "0*32", "2*20", NA, "0*61", "0*1C", "0*79", "0*16",
> > "0*44", "0*53", "0*04", "0*2D", "0*1C", "0*07", "2*37", "0*12",
> > "0*2D", "0*30", "0*6D", "0*25", "0*26", "0*75", "2*2D", "0*71",
> > "0*38", "0*6D", "0*0F", "0*34", "0*1D", "0*70", "0*47", "0*70",
> > "0*4C", "0*54", "W", "0*64", "0*66", "0*69", "0*0C", "0*70",
> > NA, "0*11", "0*28", "0*38", "0*30", "0*1F", "0*64", "0*7C", "0*38",
> > "0*67", "0*57", "0*59", "0*75", "0*52", "0*18", "0*08", "0*5F",
> > "0*26", "0*3B", "0*67", "0*6A", "2*24", "0*47", "0*65", "0*56",
> > "0*54", "2*76", "0*23", "W", "0*3B", "0*1D", "0*11"), ...8 =
> c(1485907200,
> > 1485907200, 1485907200, 1485907200, 1485907200, 1485907200, 1485907200,
> > 1485907200, 1485907200, 1485907200, 1485907200, 1485907200, 1485907200,
> > 1485907201, 1485907201, 1485907201, 1485907201, 1485907201, 1485907201,
> > 1485907201, 1485907201, 1485907201, 1485907201, 1485907201, 1485907201,
> > 1485907201, 1485907201, 0.008, 1485907201, 1485907201, 1485907201,
> > NA, 1485907203, 1485907203, 1485907203, 1485907203, 1485907203,
> > 1485907203, 1485907203, 1485907204, 1485907204, 1485907204, 1485907204,
> > 1485907204, 1485907204, 1485907204, 1485907204, 1485907204, 1485907204,
> > 1485907204, 1485907205, 1485907205, 1485907205, 1485907205, 1485907205,
> > 1485907205, 1485907205, 1485907206, 1485907206, 1485907206, 1485907206,
> > 1485907206, 0.01, 1485907206, 1485907206, 1485907206, 1485907206,
> > 1485907206, NA, 1485907206, 1485907206, 1485907206, 1485907206,
> > 1485907206, 1485907206, 1485907206, 1485907208, 1485907208, 1485907208,
> > 1485907208, 1485907208, 1485907209, 1485907209, 1485907209, 1485907209,
> > 1485907209, 1485907209, 1485907209, 1485907209, 1485907209, 1485907209,
> > 1485907209, 1485907209, 1485907209, 1485907209, 1485907209, 0.005,
> > 1485907209, 1485907209, 1485907209), ...9 = c(NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, "*41", NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, "*43", NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA), ...10 = c(NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > 10217, NA, NA, NA, 1485907201, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, 10217, NA, NA, NA, NA, NA, 1485907206,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 10217, NA, NA, NA
> > ), ...11 = c(NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA), ...12 = c(NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA),
> > ...13 = c(NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > "D*6F", NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, "D*60", NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, "D*63", NA, NA,
> > NA), ...14 = c(NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, 1485907201, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, 1485907206, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA,
> > NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 1485907209,
> > NA, NA, NA)), row.names = c(NA, -100L), class = "data.frame")
> >
> > To tested your function I took the first message, which is located in the
> > 6th column and the 1st row, and did the following:
> >
> > library(stringi)
> > library(dplyr)
> > library(R.utils)
> > library(RANN)
> > library(NISTunits)
> > library(pracma)
> > library(celestial)
> > library(stringr)
> >
> > dat <- readXL("U:/RawSampleData.xls", rownames=FALSE, header=FALSE,
> na="",
> > + sheet="RawSampleData", stringsAsFactors=FALSE)
> >
> > testmessage1 <- dat[1,6]
> >
> > ascii_datformat <- utf8ToInt(testmessage1)
> >
> > Base <- ascii_datformat - 48
> >
> > decy <- ifelse(Base > 40, Base - 8, Base)
> >
> > biny <- intToBin(decy)
> >
> > binyframe <- data.frame(biny)
> >
> > tbinyframe <- paste(t(binyframe[,1]), collapse="") #at this point, I
> have
> > the complete first message, all in binary format
> >
> > #according to the literature of AIS message decoding, longitude goes from
> > position 62 to position 89
> > #and latitude goes from position 90 to position 116
> >
> > longitude <- substr(tbinyframe, 62, 89)
> > latitude <- substr(tbinyframe, 90, 116)
> >
> > #now I apply the function you provided me with:
> >
> > fun <- function(x){
> > res <- sapply(x, function(y){
> > if(nchar(y) %% 8 != 0 || substr(y, 1, 1) == "0"){
> > strtoi(y, base = 2)
> > }else{
> > y <- unlist(strsplit(y, ""))
> > -sum((y != "1")*2^((length(y) - 1):0)) - 1
> > }
> > })
> > unname(res)
> > }
> >
> > > fun(longitude)
> > [1] 220663102
> > >
> > > fun(latitude)
> > [1] 5414823
> > >
> > > fun("1101001001110000110100111110")
> > [1] 220663102
> > >
> > > fun("000010100101001111110100111")
> > [1] 5414823
> > >
> > > fun("10110010")
> > [1] -78
> >
> > as you can see, the function only worked or showed expected result on the
> > last case with a -78, but in the other cases, it the results were not as
> > expected, maybe I am missing something here?
> >
> > Any help and/or guidance will be greatly appreciated,
> >
> > Best regards,
> >
> > Paul
> >
> > El lun., 20 ene. 2020 a las 10:28, Rui Barradas (<ruipbarra...@sapo.pt>)
> > escribió:
> >
> > > Hello,
> > >
> > > The function I included converts signed binary numbers into their
> > > decimal representation. They are negative if a) they are multiples of 8
> > > bits and b) the most significant bit is a "1". If not just convert to
> > > integer.
> > >
> > > As for a) above, I assume that you will have 8 bit numbers. And the
> > > conversion is done as follows:
> > >
> > > input: 10110010
> > >
> > > splitting, to make it more clear:
> > >
> > > 1 0 1 1 0 0 1 0 - input
> > > 0 1 0 0 1 1 0 1 - reversed
> > > 1 - add 1 to the number with reversed bits
> > > 0 1 0 0 1 1 1 0 - result is the two's complement
> > >
> > > c(0, 1, 0, 0, 1, 1, 1, 0) %*% 2^(7:0) is 78
> > >
> > > But the msb is "1" so it's -78
> > >
> > >
> > > This is what the function does, but instead of %*% it uses
> > >
> > > sum(two's compl * powers of two)
> > >
> > >
> > > Hope this helps,
> > >
> > > Rui Barradas
> > >
> > > The input must be a character string or character vector.
> > >
> > > Às 14:36 de 20/01/20, Paul Bernal escreveu:
> > > > Dear friend Rui,
> > > >
> > > > Hope you are doing great, thanks for your kind feedback. The
> challenge I
> > > > currently have at hand is to decode AIS messages and obtain latitude
> and
> > > > longitude values from those.
> > > >
> > > > So basically, I want to accomplish something like in the example
> below.
> > > > I want to convert this binary number (10110010) into the two´s
> > > > complement representation, there is the logic they are using for
> that.
> > > > Since longitude ranges from
> > > >
> > > >
> > > > Example of conversion to decimal of a signed binary number in
> > > > two's complement representation
> > > >
> > > > Let's convert to decimal the following signed binary number: 10110010
> > > >
> > > > 10110010 = -1×27 + 0×26 + 1×25 + 1×24 + 0×23 + 0×22 + 1×21 + 0×20 =
> -128
> > > > + 32 + 16 + 2 = -78.
> > > >
> > > > El lun., 20 ene. 2020 a las 7:22, Rui Barradas (<
> ruipbarra...@sapo.pt
> > > > <mailto:ruipbarra...@sapo.pt>>) escribió:
> > > >
> > > > Sorry, missunderstood the problem.
> > > > Here it goes:
> > > >
> > > > fun <- function(x){
> > > > res <- sapply(x, function(y){
> > > > if(nchar(y) %% 8 != 0 || substr(y, 1, 1) == "0"){
> > > > strtoi(y, base = 2)
> > > > }else{
> > > > y <- unlist(strsplit(y, ""))
> > > > -sum((y != "1")*2^((length(y) - 1):0)) - 1
> > > > }
> > > > })
> > > > unname(res)
> > > > }
> > > >
> > > > fun("10110010")
> > > > fun("10000000")
> > > > fun(c("01000000", "01111111", "10110010", "10000000"))
> > > >
> > > >
> > > > Hope this helps,
> > > >
> > > > Rui Barradas
> > > >
> > > > Às 11:38 de 20/01/20, Rui Barradas escreveu:
> > > > > Hello,
> > > > >
> > > > > Is this what you want?
> > > > >
> > > > >
> > > > > x <- "10110010"
> > > > > strtoi(x, base = 2)
> > > > > #[1] 178
> > > > >
> > > > >
> > > > > Hope this helps,
> > > > >
> > > > > Rui Barradas
> > > > >
> > > > > Às 16:31 de 16/01/20, Paul Bernal escreveu:
> > > > >> Dear friends,
> > > > >>
> > > > >> How can I convert the following binary number in two´s
> complement
> > > > >> representation in R?
> > > > >>
> > > > >> 10110010
> > > > >>
> > > > >> Any help and/or guidance will be greatly appreciated,
> > > > >>
> > > > >> Best regards,
> > > > >>
> > > > >> Paul
> > > > >>
> > > > >> [[alternative HTML version deleted]]
> > > > >>
> > > > >> ______________________________________________
> > > > >> R-help@r-project.org <mailto:R-help@r-project.org> mailing
> list
> > > > -- To UNSUBSCRIBE and more, see
> > > > >> https://stat.ethz.ch/mailman/listinfo/r-help
> > > > >> PLEASE do read the posting guide
> > > > >> http://www.R-project.org/posting-guide.html
> > > > >> and provide commented, minimal, self-contained, reproducible
> > > code.
> > > > >>
> > > > >
> > > > > ______________________________________________
> > > > > R-help@r-project.org <mailto:R-help@r-project.org> mailing
> list
> > > > -- To UNSUBSCRIBE and more, see
> > > > > https://stat.ethz.ch/mailman/listinfo/r-help
> > > > > PLEASE do read the posting guide
> > > > > http://www.R-project.org/posting-guide.html
> > > > > and provide commented, minimal, self-contained, reproducible
> code.
> > > >
> > >
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
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