Converting entries from array to double from an entire column in a matrix for plotting

I have this file which I want to analyse for temeprature fluctuations:

D=readtable('tempDataTrollhFlygpl.xlsx', 'NumHeaderLines', 10) % anger 10 rubrikrader slik at jeg kan ekstrahere kolonne entries mer effektivt
val = str2double(D{:,3});
val2 = str2double(D{:,4});
plot(D,'Var3','Var4')

So I triwed to convert all entries in table 3 and 4 to doubles, so that they can be plotted by calling their sets as "val" and "val2", but those names were not recognized by plot, so I used what MATLAB suggested, namely Var3 and Var4, for the 3d and 4th respective columns.

How can I can plot this, and also, how can I find the most recurring number in the column 4, that is the most recurring temperature over that period defined in column 3?

I was also trying to view the distribution of the temperatures as a histogram, so I did the following:

histogram(val2,val)

But also this didn't work.

Any ideas appreaciated!

Thanks

Answer 1

[Dyuman Joshi]

Change the options for reading the data via detectImportOptions and use column numbers to plot -

opts = detectImportOptions('tempDataTrollhFlygpl.xlsx')

opts = 
  SpreadsheetImportOptions with properties:

   Sheet Properties:
                        Sheet: ''

   Replacement Properties:
                  MissingRule: 'fill'
              ImportErrorRule: 'fill'

   Variable Import Properties: Set types by name using setvartype
                VariableNames: {'Tidsperiod_fr_o_m_', 'Tidsperiod_t_o_m_', 'H_jd_meter_verHavet_' ... and 4 more}
                VariableTypes: {'datetime', 'datetime', 'datetime' ... and 4 more}
        SelectedVariableNames: {'Tidsperiod_fr_o_m_', 'Tidsperiod_t_o_m_', 'H_jd_meter_verHavet_' ... and 4 more}
              VariableOptions: [1-by-7 matlab.io.VariableImportOptions] 
	Access VariableOptions sub-properties using setvaropts/getvaropts
           VariableNamingRule: 'modify'

   Range Properties:
                    DataRange: 'A8' (Start Cell)
           VariableNamesRange: 'A7'
                RowNamesRange: ''
           VariableUnitsRange: ''
    VariableDescriptionsRange: '' 
	To display a preview of the table, use preview

%Change the data type of column 4
opts.VariableTypes{4} = 'double';
%Assign the 10th row for variable names
opts.VariableNamesRange = '10:10';
%Assign the cell from which to start reading the data
opts.DataRange = 'A11';

D = readtable('tempDataTrollhFlygpl.xlsx', opts) % anger 10 rubrikrader slik at jeg kan ekstrahere kolonne entries mer effektivt

Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.

D = 6786x7 table
     Fr_nDatumTid_UTC_      TillDatumTid_UTC_    RepresentativtDygn    Lufttemperatur    Kvalitet       Var6                                                                       Tidsutsnitt_                                                                 
    ____________________    _________________    __________________    ______________    ________    __________    _____________________________________________________________________________________________________________________________________________

    01-Jan-1961 00:00:01       02-Jan-1961          01-Jan-1961              0.1          {'Y'}      {0x0 char}    {'Kvalitetskontrollerade historiska data (utom de senaste 3 mån)'                                                                           }
    02-Jan-1961 00:00:01       03-Jan-1961          02-Jan-1961              0.7          {'Y'}      {0x0 char}    {'Tidsperiod (fr.o.m.) = 1961-01-01 00:00:00 (UTC)'                                                                                         }
    03-Jan-1961 00:00:01       04-Jan-1961          03-Jan-1961                1          {'Y'}      {0x0 char}    {'Tidsperiod (t.o.m.) = 1979-08-01 23:59:59 (UTC)'                                                                                          }
    04-Jan-1961 00:00:01       05-Jan-1961          04-Jan-1961              0.4          {'Y'}      {0x0 char}    {'Medelvärdet är beräknat för = 24 timmar'                                                                                                  }
    05-Jan-1961 00:00:01       06-Jan-1961          05-Jan-1961                0          {'Y'}      {0x0 char}    {0x0 char                                                                                                                                   }
    06-Jan-1961 00:00:01       07-Jan-1961          06-Jan-1961              0.2          {'Y'}      {0x0 char}    {'Kvalitetskoderna:'                                                                                                                        }
    07-Jan-1961 00:00:01       08-Jan-1961          07-Jan-1961                0          {'Y'}      {0x0 char}    {'Grön (G) = Kontrollerade och godkända värden.'                                                                                            }
    08-Jan-1961 00:00:01       09-Jan-1961          08-Jan-1961             -1.1          {'Y'}      {0x0 char}    {'Gul (Y) = Misstänkta eller aggregerade värden. Grovt kontrollerade arkivdata och okontrollerade realtidsdata (senaste 2 tim).'            }
    09-Jan-1961 00:00:01       10-Jan-1961          09-Jan-1961             -1.1          {'Y'}      {0x0 char}    {0x0 char                                                                                                                                   }
    10-Jan-1961 00:00:01       11-Jan-1961          10-Jan-1961             -0.8          {'Y'}      {0x0 char}    {'Orsaker till saknade data:'                                                                                                               }
    11-Jan-1961 00:00:01       12-Jan-1961          11-Jan-1961             -5.4          {'Y'}      {0x0 char}    {'stationen eller givaren har varit ur funktion.'                                                                                           }
    12-Jan-1961 00:00:01       13-Jan-1961          12-Jan-1961             -6.8          {'Y'}      {0x0 char}    {'kvalitetskontrollerna har felmarkerat data (röd kvalitetskod). Efterföljande manuell granskning godkänner, rättar eller underkänner data.'}
    13-Jan-1961 00:00:01       14-Jan-1961          13-Jan-1961              2.6          {'Y'}      {0x0 char}    {0x0 char                                                                                                                                   }
    14-Jan-1961 00:00:01       15-Jan-1961          14-Jan-1961              0.3          {'Y'}      {0x0 char}    {0x0 char                                                                                                                                   }
    15-Jan-1961 00:00:01       16-Jan-1961          15-Jan-1961              2.5          {'Y'}      {0x0 char}    {0x0 char                                                                                                                                   }
    16-Jan-1961 00:00:01       17-Jan-1961          16-Jan-1961             -2.7          {'Y'}      {0x0 char}    {0x0 char                                                                                                                                   }

plot(D, 3, 4)

Answer 2

[Mathieu NOE]

hello

here you are

D=readtable('tempDataTrollhFlygpl.xlsx', 'NumHeaderLines', 10) % anger 10 rubrikrader slik at jeg kan ekstrahere kolonne entries mer effektivt

D = 6786x7 table
            Var1               Var2           Var3          Var4      Var5     Var6                                                                        Var7                                                                     
    ____________________    ___________    ___________    ________    _____    ____    _____________________________________________________________________________________________________________________________________________

    01-Jan-1961 00:00:01    02-Jan-1961    01-Jan-1961    {'0.1' }    {'Y'}    NaN     {'Kvalitetskontrollerade historiska data (utom de senaste 3 mån)'                                                                           }
    02-Jan-1961 00:00:01    03-Jan-1961    02-Jan-1961    {'0.7' }    {'Y'}    NaN     {'Tidsperiod (fr.o.m.) = 1961-01-01 00:00:00 (UTC)'                                                                                         }
    03-Jan-1961 00:00:01    04-Jan-1961    03-Jan-1961    {'1.0' }    {'Y'}    NaN     {'Tidsperiod (t.o.m.) = 1979-08-01 23:59:59 (UTC)'                                                                                          }
    04-Jan-1961 00:00:01    05-Jan-1961    04-Jan-1961    {'0.4' }    {'Y'}    NaN     {'Medelvärdet är beräknat för = 24 timmar'                                                                                                  }
    05-Jan-1961 00:00:01    06-Jan-1961    05-Jan-1961    {'0.0' }    {'Y'}    NaN     {0x0 char                                                                                                                                   }
    06-Jan-1961 00:00:01    07-Jan-1961    06-Jan-1961    {'0.2' }    {'Y'}    NaN     {'Kvalitetskoderna:'                                                                                                                        }
    07-Jan-1961 00:00:01    08-Jan-1961    07-Jan-1961    {'0.0' }    {'Y'}    NaN     {'Grön (G) = Kontrollerade och godkända värden.'                                                                                            }
    08-Jan-1961 00:00:01    09-Jan-1961    08-Jan-1961    {'-1.1'}    {'Y'}    NaN     {'Gul (Y) = Misstänkta eller aggregerade värden. Grovt kontrollerade arkivdata och okontrollerade realtidsdata (senaste 2 tim).'            }
    09-Jan-1961 00:00:01    10-Jan-1961    09-Jan-1961    {'-1.1'}    {'Y'}    NaN     {0x0 char                                                                                                                                   }
    10-Jan-1961 00:00:01    11-Jan-1961    10-Jan-1961    {'-0.8'}    {'Y'}    NaN     {'Orsaker till saknade data:'                                                                                                               }
    11-Jan-1961 00:00:01    12-Jan-1961    11-Jan-1961    {'-5.4'}    {'Y'}    NaN     {'stationen eller givaren har varit ur funktion.'                                                                                           }
    12-Jan-1961 00:00:01    13-Jan-1961    12-Jan-1961    {'-6.8'}    {'Y'}    NaN     {'kvalitetskontrollerna har felmarkerat data (röd kvalitetskod). Efterföljande manuell granskning godkänner, rättar eller underkänner data.'}
    13-Jan-1961 00:00:01    14-Jan-1961    13-Jan-1961    {'2.6' }    {'Y'}    NaN     {0x0 char                                                                                                                                   }
    14-Jan-1961 00:00:01    15-Jan-1961    14-Jan-1961    {'0.3' }    {'Y'}    NaN     {0x0 char                                                                                                                                   }
    15-Jan-1961 00:00:01    16-Jan-1961    15-Jan-1961    {'2.5' }    {'Y'}    NaN     {0x0 char                                                                                                                                   }
    16-Jan-1961 00:00:01    17-Jan-1961    16-Jan-1961    {'-2.7'}    {'Y'}    NaN     {0x0 char                                                                                                                                   }

time = D{:,3};
temp = str2double(D{:,4});

figure(1)
plot(time,temp)

figure(2)
histogram(temp)

[Sergio]

Something was wrong with the histogram. The temperature is only a few degrees, while the histogram command gives y-values of several hundreds of degrees!

[Star Strider]

The ‘y’ values are not degrees. They are the number of times a particular degree value (x-axis) appears in the ‘Var4’ data.

[Sergio]

Starstrider, thanks!