I have a .csv file with a list of numbers, what code can I use to check if an inputted number exists in that file.

I have a .csv file that contains a list of account numbers. How can i check if an inputted number exists in that file. so for example, I write

AN= 256. What code can I use to check if '256' exists in the .csv file or not.

Answer 1

[Walter Roberson]

readtable(). ismember() the appropriate column of the table.

[Tariq Hammoudeh]

im sorry but what goes in the paranthesis, also is there a way to use if. so if AN exists in the csv file

[Walter Roberson]

No, there is no MATLAB function that you can pass in a file name and a value and get back the response Yes the value exists in the file or No it does not exist in the file.

You need to read the data in and test the values once they are in memory.

help readtable

 READTABLE Create a table by reading from a file.
 
    Use the READTABLE function to create a table by reading column-oriented
    data from a file. READTABLE automatically determines the file format from
    its extension as described below.
 
    T = READTABLE(FILENAME) creates a table by reading from a file, where
    FILENAME can be one of these:
 
        - For local files, FILENAME can be a full path that contains
          a filename and file extension. FILENAME can also be a relative path
          to the current folder, or to a folder on the MATLAB path.
          For example, to import a file on the MATLAB path:
 
             T = readtable("patients.xls");
 
        - For files from an Internet URL or stored at a remote location,
          FILENAME must be a full path using a Uniform Resource Locator
          (URL). For example, to import a remote file from Amazon S3,
          specify the full URL for the file:
 
             T = readtable("s3://bucketname/path_to_file/my_table.xls");
 
          For more information on accessing remote data, see "Work with
          Remote Data" in the documentation.
 
    T = READTABLE(FILENAME,"FileType",FILETYPE) specifies the file type, where
    FILETYPE is one of "text", "delimitedtext", "fixedwidth", "spreadsheet",
    "xml", "html", or "worddocument".
 
    T = READTABLE(FILENAME,OPTS) creates a table by reading from a file stored
    at FILENAME using the supplied ImportOptions OPTS. OPTS specifies variable
    names, selected variable names, variable types, and other information regarding
    the location of the data.
 
    For example, import a subset of the data in a file:
 
        opts = detectImportOptions("patients.xls");
        opts.SelectedVariableNames = ["Systolic","Diastolic"];
        T = readtable("patients.xls",opts)
 
    READTABLE reads data from different file types as follows:
 
    Text files (delimited and fixed-width): 
 
      The following extensions are supported: .txt, .dat, .csv, .log,
                                              .text, .dlm
 
      Reading from a delimited text file creates one variable in T for each
      column in the file. Variable names can be taken from the first row of
      the file. By default, the variables created are either double, if the
      column is primarily numeric, or datetime, duration, or text etc. If
      data in a column cannot be converted to numeric, datetime or
      duration, the column is imported as text.
 
    Spreadsheet files:
 
      The following extensions are supported: .xls, .xlsx, .xlsb, .xlsm, 
                                              .xltm, .xltx, .ods
 
      Reading from a spreadsheet file creates one variable in T for each
      column in the file. By default, the variables created are either
      double, datetime or text--depending on the type in the file.
 
      READTABLE converts both empty fields or cells and values which cannot
      be converted to the expected type to:
        - NaN (for a numeric or duration variable),
        - NaT (for a datetime variable),
        - Empty character vector ('') or missing string (for text variables).
 
    Word documents:
 
      The following extensions are supported: .docx
 
      Reading from a Word document file imports data from a table. Each column
      in the table creates one variable in T. Variable names can be taken from
      the first row of the table. By default, the variables created are either
      double, if the column is primarily numeric, or datetime, duration, or
      text etc. If data in a column cannot be converted to numeric, datetime
      or duration, the column is imported as text. The default data type for
      text import is string.
 
    HTML files: 
 
      The following extensions are supported: .html, .xhtml, .htm
 
      Reading from an HTML file imports data from a <TABLE> element. Each
      column in the table creates one variable in T. Variable names can be
      taken from the first row of the table. By default, the variables created
      are either double, if the column is primarily numeric, or datetime,
      duration, or text etc. If data in a column cannot be converted to
      numeric, datetime or duration, the column is imported as text. The
      default data type for text import is string.
 
    XML files:
 
      The following extensions are supported: .xml
 
      Tabular structure present within an XML file:
 
          <table> ----------------------------- Table Node
              <row> --------------------------- Row Node
                  <date>2019-07-11</date> ----- Variable Node
                  <index>8191</index>
                  <name>Lorem</name>
              </row>
              <row>
                  <date>2020-01-04</date>
                  <index>131071</index>
                  <name>Ipsum</name>
              </row>
          </table>
 
      Reading from an XML file creates one row in T for each repeated node
      in the file that is detected under the table node. Variable names are
      taken from the names of the child nodes under the row nodes in the file.
 
    Name-Value Pairs for ALL file types:
    ------------------------------------
 
    "FileType"              - Specify the file as "text", "delimitedtext",
                              "fixedwidth", "spreadsheet", "xml", "html",
                              or "worddocument".
 
    "VariableNamingRule"    - A character vector or a string scalar that
                              specifies how the output variables are named.
                              It can have either of the following values:
 
                              'modify'   Modify variable names to make them
                                         valid MATLAB Identifiers.
                                         (default)
                              'preserve' Preserve original variable names
                                         allowing names with spaces and
                                         non-ASCII characters.
 
    "MissingRule"           - Rules for interpreting missing or
                              unavailable data:
                              "fill"      Replace missing data with the
                                          contents of the "FillValue"
                                          property.
                              "error"     Stop importing and display an
                                          error message showing the missing
                                          record and field.
                              "omitrow"   Omit rows that contain missing
                                          data.
                              "omitvar"   Omit variables that contain
                                          missing data.
 
    "ImportErrorRule"       - Rules for interpreting nonconvertible
                              or bad data:
                              "fill"      Replace the data where errors
                                          occur with the contents of the
                                          "FillValue" property.
                              "error"     Stop importing and display an
                                          error message showing the
                                          error-causing record and field.
                              "omitrow"   Omit rows where errors occur.
                              "omitvar"   Omit variables where errors
                                          occur.
 
    "ReadRowNames"          - Whether or not to import the first variable
                              as row names. Defaults to false.
 
    "TreatAsMissing"        - Text which is used in a file to represent
                              missing data, e.g. "NA".
 
    "TextType"              - The type to use for text variables, specified
                              as "char" or "string".
 
    "DatetimeType"          - The type to use for date variables, specified
                              as "datetime", "text", or "exceldatenum".
                              Defaults to "datetime".
 
    Name-Value Pairs for TEXT and SPREADSHEET only:
    -----------------------------------------------
 
    "Range"                 - The range to consider when detecting data.
                              Specified using any of the following syntaxes:
                              - Starting cell: A string or character vector
                                containing a column letter and a row number,
                                or a 2 element numeric vector indicating
                                the starting row and column.
                              - Rectangular range: A start and end cell separated
                                by colon, e.g. "C2:N15", or a four element
                                numeric vector containing start row, start
                                column, end row, end column, e.g. [2 3 15 13].
                              - Row range: A string or character vector
                                containing a starting row number and ending
                                row number, separated by a colon.
                              - Column range: A string or character vector
                                containing a starting column letter and
                                ending column letter, separated by a colon.
                              - Starting row number: A numeric scalar
                                indicating the first row where data is found.
 
    "NumHeaderLines"        - The number of header lines in the file.
 
    "ExpectedNumVariables"  - The expected number of variables.
 
    "ReadVariableNames"     - Whether or not to expect variable names in
                              the file. Defaults to true.
 
    Name-Value Pairs for TEXT, XML, HTML, and Word documents only:
    --------------------------------------------------------------
 
    "DateLocale"         - The locale used to interpret month and day
                           names in datetime text. Must be a character
                           vector or scalar string in the form xx_YY.
                           See the documentation for DATETIME for more
                           information.
 
    "DecimalSeparator"   - Character used to separate the integer part
                           of a number from the decimal part of the
                           number.
 
    "ThousandsSeparator" - Character used to separate the thousands
                           place digits.
 
    Name-Value Pairs for TEXT, XML, and HTML only:
    ----------------------------------------------
 
    "Encoding"           - The character encoding scheme associated with
                           the file.
 
    Name-Value Pairs for TEXT and XML only:
    ---------------------------------------
 
    "DurationType"       - The type to use for duration, specified as
                           "duration" or "text". Defaults to "duration".
 
    "Whitespace"         - Characters to treat as whitespace.
 
    "TrimNonNumeric"     - Whether or not to remove nonnumeric characters
                           from a numeric variable. Defaults to false.
 
    "HexType"            - Set the output type of a hexadecimal
                           variable.
 
    "BinaryType"         - Set the output type of a binary variable.
 
    "CollectOutput"      - Whether or not to concatenate consecutive output
                           of the same MATLAB class into a single array.
                           Defaults to false.
 
    Name-Value Pairs for TEXT, HTML, and Word documents only:
    ---------------------------------------------------------
 
    "RowNamesColumn"     - The column where the row names are
                           located.
 
    Name-Value Pairs for TEXT only:
    -------------------------------
 
    "Delimiter"                 - Field delimiter characters in a delimited
                                  text file, specified as a character
                                  vector, string scalar, cell array of
                                  character vectors, or string array.
 
    "CommentStyle"              - Style of comments, specified as a
                                  character vector, string scalar, cell
                                  array of character vectors, or string
                                  array.
 
    "LineEnding"                - End-of-line characters, specified as a
                                  character vector, string scalar, cell
                                  array of character vectors, or string
                                  array.
 
    "ConsecutiveDelimitersRule" - Rule to apply to fields containing
                                  multiple consecutive delimiters:
                                  "split"     Split consecutive delimiters
                                              into multiple fields.
                                  "join"      Join the delimiters into one
                                              single delimiter.
                                  "error"     Ignore consecutive delimiters
                                              during detection (treated as
                                              "split"), but the
                                              resulting read will error.
 
    "LeadingDelimitersRule"     - Rule to apply to delimiters at the
                                  beginning of a line:
                                  "keep"      Keep leading delimiters.
                                  "ignore"    Ignore leading delimiters.
                                  "error"     Ignore leading delimiters
                                              during detection, but the
                                              resulting read will error.
 
    "TrailingDelimiterRule"     - Rule to apply to delimiters at the
                                  end of a line:
                                  "keep"      Keep trailing delimiters.
                                  "ignore"    Ignore trailing delimiters.
                                  "error"     Ignore trailing delimiters
                                              during detection, but the
                                              resulting read will error.
 
    "VariableWidths"            - Widths of the variables for a fixed width
                                  file.
 
    "EmptyLineRule"             - Rule to apply to empty lines in the file:
                                  "skip"      Skip empty lines.
                                  "read"      Read empty lines.
                                  "error"     Ignore empty lines during
                                              detection, but the resulting
                                              read will error.
 
    "VariableNamesLine"         - The line where the variable names are
                                  located.
 
    "PartialFieldRule"          - Rule to handle partial fields in the data:
                                  "keep"      Keep the partial field data
                                              and convert the text to the
                                              appropriate data type.
                                  "fill"      Replace missing data with the
                                              contents of the "FillValue"
                                              property.
                                  "omitrow"   Omit rows that contain
                                              partial data.
                                  "omitvar"   Omit variables that contain
                                              partial data.
                                  "wrap"      Begin reading the next line
                                              of characters.
                                  "error"     Ignore partial field data
                                              during detection, but the
                                              resulting read will error.
 
    "VariableUnitsLine"         - The line where the variable units are
                                  located.
 
    "VariableDescriptionsLine"  - The line where the variable descriptions
                                  are located.
 
    "ExtraColumnsRule"          - Rule to apply to extra columns of data
                                  that appear after the expected variables:
                                  "addvars"   Creates new variables to 
                                              import extra columns. If there
                                              are N extra columns, then import
                                              new variables as "ExtraVar1",
                                              "ExtraVar2",..., "ExtraVarN".
                                  "ignore"    Ignore the extra columns of
                                              data.
                                  "wrap"      Wrap the extra columns of
                                              data to new records.
                                  "error"     Display an error message and
                                              abort the import operation.
 
    Name-Value Pairs for SPREADSHEET only:
    --------------------------------------
 
    "UseExcel"                  - Whether or not to read the spreadsheet
                                  file using Microsoft(R) Excel(R) on 
                                  Windows(R):
                                  true  - Opens an instance of Microsoft Excel
                                          to read the file on a Windows system
                                          with Excel installed.
                                  false - Does not open an instance of Microsoft
                                          Excel to read the file. This is the
                                          default setting.
 
    "Sheet"                     - The sheet from which to read the table.
 
    "DataRange"                 - Where the table data is located.
 
    "RowNamesRange"             - Where the row names are located.
 
    "VariableNamesRange"        - Where the variable names are located.
 
    "VariableUnitsRange"        - Where the variable units are located.
 
    "VariableDescriptionsRange" - Where the variable descriptions are
                                  located.
 
    Name-Value Pairs for HTML and Word documents only:
    --------------------------------------------------
 
    "TableIndex"                - Integer selection which table to extract.
 
    "VariableNamesRow"          - The row where the variable names are
                                  located.
 
    "VariableUnitsRow"          - The row where the variable units are
                                  located.
 
    "VariableDescriptionsRow"   - The row where the variable descriptions
                                  are located.
 
    "EmptyRowRule"              - Rule to apply to empty lines in the file:
                                  "skip"      Skip empty lines.
                                  "read"      Read empty lines.
                                  "error"     Ignore empty lines during
                                              detection, but the resulting
                                              read will error.
 
    "EmptyColumnRule"           - Rule to apply to empty columns in the file:
                                  "skip"      Skip empty columns.
                                  "read"      Read empty columns.
                                  "error"     Error on empty columns.
 
    Name-Value Pairs for HTML, Word documents, and XML only:
    --------------------------------------------------------
 
    "TableSelector"             - XPath expression that selects the table
                                  to extract.
 
    Name-Value Pairs for XML only:
    ------------------------------
 
    "RowNodeName"                  - Node name which delineates rows of
                                     the output table.
 
    "RowSelector"                  - XPath expression that selects the XML
                                     Element nodes which delineate rows of
                                     the output table.
 
    "VariableNodeNames"            - Node names which will be treated as
                                     variables of the output table.
 
    "VariableSelectors"            - XPath expressions that select the XML
                                     Element nodes to be treated as variables
                                     of the output table.
 
    "TableNodeName"                - Name of the node which contains table
                                     data. If multiple nodes have the same
                                     name, READTABLE uses the first node
                                     with that name.
 
    "VariableUnitsSelector"        - XPath expression that selects the XML
                                     Element nodes containing the variable
                                     units.
 
    "VariableDescriptionsSelector" - XPath expression that selects the XML
                                     Element nodes containing the variable
                                     descriptions.
 
    "RowNamesSelector"             - XPath expression that selects the XML
                                     Element nodes containing the row names.
 
    "RepeatedNodeRule"             - Rule for managing repeated nodes in a
                                     given row of a table:
                                     "addcol"     Add a column for each
                                                  repeated node.
                                     "ignore"     Ignore repeated nodes.
                                     "error"      Ignore repeated nodes
                                                  during detection, but the
                                                  resulting read will error.
 
    "ImportAttributes"             - Import XML node attributes as variables
                                     of the output table. Defaults to true.
 
    "AttributeSuffix"              - Suffix to append to all output table
                                     variable names corresponding to
                                     attributes in the XML file. Defaults
                                     to "Attribute".
 
    "RegisteredNamespaces"         - The namespace prefixes that are mapped
                                     to namespace URLs for use in selector
                                     expressions.
 
    Name-Value Pairs supported with Text and Spreadsheet Import Options OPTS:
    -------------------------------------------------------------------------
 
    These have slightly different behavior when used with import options:
 
        T = readtable(FILENAME, OPTS, "Name1", Value1, "Name2", Value2, ...)
 
          "ReadVariableNames" true  - Reads the variable names from the
                                      opts.VariableNamesRange or opts.VariableNamesLine
                                      location.
                              false - Uses variable names from the import options.
 
          "ReadRowNames"      true  - Reads the row names from the opts.RowNamesRange
                                      or opts.RowNamesColumn location.
                              false - Does not import row names.
 
        Text parameters:
          "DateLocale" - Override the locale used when importing dates.
          "Encoding"   - Override the encoding defined in import options.
 
        Spreadsheet only parameters:
          "Sheet"    - Override the sheet value in the import options.
 
    See also READTIMETABLE, READMATRIX, READCELL, WRITETABLE, TABLE,
             DETECTIMPORTOPTIONS, TEXTSCAN.

    Documentation for readtable
       doc readtable

help ismember

 ISMEMBER True for set member.
    LIA = ISMEMBER(A,B) for arrays A and B returns an array of the same
    size as A containing true where the elements of A are in B and false
    otherwise.
 
    LIA = ISMEMBER(A,B,'rows') for matrices A and B with the same number
    of columns, returns a vector containing true where the rows of A are
    also rows of B and false otherwise.
 
    [LIA,LOCB] = ISMEMBER(A,B) also returns an array LOCB containing the
    lowest absolute index in B for each element in A which is a member of
    B and 0 if there is no such index.
 
    [LIA,LOCB] = ISMEMBER(A,B,'rows') also returns a vector LOCB containing
    the lowest absolute index in B for each row in A which is a member
    of B and 0 if there is no such index.
 
    The behavior of ISMEMBER has changed.  This includes:
      -	occurrence of indices in LOCB switched from highest to lowest
      -	tighter restrictions on combinations of classes
 
    If this change in behavior has adversely affected your code, you may
    preserve the previous behavior with:
 
       [LIA,LOCB] = ISMEMBER(A,B,'legacy')
       [LIA,LOCB] = ISMEMBER(A,B,'rows','legacy')
 
    Examples:
 
       a = [9 9 8 8 7 7 7 6 6 6 5 5 4 4 2 1 1 1]
       b = [1 1 1 3 3 3 3 3 4 4 4 4 4 9 9 9]
 
       [lia1,locb1] = ismember(a,b)
       % returns
       lia1 = [1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 1 1 1]
       locb1 = [14 14 0 0 0 0 0 0 0 0 0 0 9 9 0 1 1 1]
 
       [lia,locb] = ismember([1 NaN 2 3],[3 4 NaN 1])
       % NaNs compare as not equal, so this returns
       lia = [1 0 0 1], locb = [4 0 0 1]
 
    Class support for inputs A and B, where A and B must be of the same
    class unless stated otherwise:
       - logical, char, all numeric classes (may combine with double arrays)
       - cell arrays of strings (may combine with char arrays)
       -- 'rows' option is not supported for cell arrays
       - objects with methods SORT (SORTROWS for the 'rows' option), EQ and NE
       -- including heterogeneous arrays derived from the same root class
 
    See also ISMEMBERTOL, INTERSECT, UNION, UNIQUE, UNIQUETOL, SETDIFF,
             SETXOR, SORT, SORTROWS.

    Documentation for ismember
       doc ismember

    Other functions named ismember

       categorical/ismember    mtree/ismember
       cell/ismember           nominal/ismember
       dataset/ismember        sym/ismember
       datetime/ismember       tabular/ismember
       duration/ismember       tall/ismember
       gpuArray/ismember       textanalytics.internal.wordlist/ismember