Grouping Categories in Scatter Plot

Hello everyone! I have a scatter plot that I am working on and am trying to figure out how to code the groups out. I need different colors to represent different groups. For example Hudson river, Nile river etc. I have 6 rivers. I tried to create a 6x1 line array but that isn't working. Any ideas?

[dpb]

As per usual, if you'll share the actual data or something similar, it gets much easier to write specific code.

You can pass either a color triplet array or a vector into the current colormap for each vector using scatter() if you have different vectors for each river or use a given color index/triplet for a specific grouping variable (the river ID) to plot all as a single vector.

plot() will cycle colors for each line in an array treating each column as a separate line; if the data lengths aren't the same for all groups/columns (rivers), then fill in to the length of the longest with NaN; those locations will be transparently ignored.

Answer 1

[Sulaymon Eshkabilov]

If understood your question correctly, here is one example how to address this issue:

DATA = randi(100, 25, 1);
BIN = discretize(DATA, [1, 20, 41, 61, 81 100], 'categorical',{'Agrade',  'Bgrade',   'Cgrade',   'Dgrade',   'Egrade'});
hist(BIN)

Answer 2

[Star Strider]

The gscatter function may be appropriate.

Is this the correct file? These don’t appear to have anything to do with rivers (although I didn’t look past what’s displayed here) ...

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1303475/WATEDR%20COPY%202.csv', 'VariableNamingRule','preserve')

T1 = 8541×9 table
    Facility description    Date collected            Component            Result entry    Unit of measure                          Location description                            Test code       Test status     Sample status
    ____________________    ______________    _________________________    ____________    _______________    ________________________________________________________________    _____________    _____________    _____________

    {'FELLS RESERVOIR'}      17-Aug-2010      {'Alkalinity'           }        17.2        {'mg/L'      }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'ALK-AQTPO'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'Ca Final'             }        4010        {'ug/L'      }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'ICP-DWAXI'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'Chlorophyll A'        }          17        {'ug/L'      }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'CHLAAQFLU'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'Cl'                   }        8.04        {'mg/L'      }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'ICA-AQICC'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'DO'                   }        8.45        {'mg/L'      }     {'0.5M DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1*)'    }    {'DO--AQFLD'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'DO Percent Saturation'}         102        {'%'         }     {'0.5M DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1*)'    }    {'DOPSAQFLD'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'Depth to Bottom'      }         0.2        {'m'         }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'TDEPAQFLD'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'E. coli'              }        37.9        {'MPN/100 mL'}     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'ECOLAQC18'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'Fe Final'             }          73        {'ug/L'      }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'ICP-DWAXI'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'Fecal Coliform'       }          62        {'CFU/100ML' }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'FCOLAQMFL'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'Hardness'             }        13.6        {'mg/L'      }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'ICP-DWAXI'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'Mg Final'             }         880        {'ug/L'      }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'ICP-DWAXI'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'Mn Final'             }        19.6        {'ug/L'      }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'ICP-DWAXI'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'NH3-N'                }         NaN        {'mg/L'      }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'NUTFAQAAN'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'NO32-N'               }         NaN        {'mg/L'      }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'NUTFAQAAN'}    {'VALIDATED'}    {'APPROVED'} 
    {'FELLS RESERVOIR'}      17-Aug-2010      {'Phaeophytin'          }        1.79        {'ug/L'      }     {'SURFACE DEPTH-WEST AREA NEAR GATEHOUSE (SHORE SITE FOR F1-S)'}    {'CHLAAQFLU'}    {'VALIDATED'}    {'APPROVED'} 

T1(end-9:end,:)

ans = 10×9 table
    Facility description     Date collected         Component          Result entry    Unit of measure                             Location description                                Test code       Test status     Sample status
    _____________________    ______________    ____________________    ____________    _______________    _______________________________________________________________________    _____________    _____________    _____________

    {'SUDBURY RESERVOIR'}     26-Jul-2022      {'TempC'           }        13.5           {'Deg-C'}       {'SURFACE SAMPLE AT DAM (GATEHOUSE)'                                  }    {'TMPCAQFLD'}    {'VALIDATED'}    {'APPROVED'} 
    {'SUDBURY RESERVOIR'}     26-Jul-2022      {'Turbidity'       }        1.57           {'NTU'  }       {'Deepest location - near 42°18'28.74"N 71°29'42.6"W - bottom sample' }    {'TURBAQFLD'}    {'VALIDATED'}    {'APPROVED'} 
    {'SUDBURY RESERVOIR'}     26-Jul-2022      {'Turbidity'       }        0.29           {'NTU'  }       {'Deepest location - near 42°18'28.74"N 71°29'42.6"W - surface sample'}    {'TURBAQFLD'}    {'VALIDATED'}    {'APPROVED'} 
    {'SUDBURY RESERVOIR'}     26-Jul-2022      {'Turbidity'       }        1.12           {'NTU'  }       {'SURFACE SAMPLE AT DAM (GATEHOUSE)'                                  }    {'TURBAQFLD'}    {'VALIDATED'}    {'APPROVED'} 
    {'SUDBURY RESERVOIR'}     26-Jul-2022      {'UV Scan Filename'}         NaN           {'-'    }       {'Deepest location - near 42°18'28.74"N 71°29'42.6"W - bottom sample' }    {'UV--AQUVV'}    {'VALIDATED'}    {'APPROVED'} 
    {'SUDBURY RESERVOIR'}     26-Jul-2022      {'UV Scan Filename'}         NaN           {'-'    }       {'Deepest location - near 42°18'28.74"N 71°29'42.6"W - surface sample'}    {'UV--AQUVV'}    {'VALIDATED'}    {'APPROVED'} 
    {'SUDBURY RESERVOIR'}     26-Jul-2022      {'UV Scan Filename'}         NaN           {'-'    }       {'SURFACE SAMPLE AT DAM (GATEHOUSE)'                                  }    {'UV--AQUVV'}    {'VALIDATED'}    {'APPROVED'} 
    {'SUDBURY RESERVOIR'}     26-Jul-2022      {'pH'              }        6.55           {'S.U.' }       {'Deepest location - near 42°18'28.74"N 71°29'42.6"W - bottom sample' }    {'PH--AQFLD'}    {'VALIDATED'}    {'APPROVED'} 
    {'SUDBURY RESERVOIR'}     26-Jul-2022      {'pH'              }        8.06           {'S.U.' }       {'Deepest location - near 42°18'28.74"N 71°29'42.6"W - surface sample'}    {'PH--AQFLD'}    {'VALIDATED'}    {'APPROVED'} 
    {'SUDBURY RESERVOIR'}     26-Jul-2022      {'pH'              }        6.59           {'S.U.' }       {'SURFACE SAMPLE AT DAM (GATEHOUSE)'                                  }    {'PH--AQFLD'}    {'VALIDATED'}    {'APPROVED'} 

.

[Stephanie]

yes, I put rivers as an example because I shouldn't really be sharing the exact data.

Stef

[Image Analyst]

So what are the two or three features/values that you will have along each axis in your scatter plot? Do you want a 2-D scatter or 3-D scatter (for 3 features/attributes)

[Star Strider]

O.K. I cannot do anything meaningful with the information in that file, so use the link I provided to see if the gscatter function will do what you want.

.