graph - JasperReports CategoryDataset has less data than expected? -

i'm trying develop chartcustomizer takes data chart , converts histogram (because jr not directly support histograms). it's simple implementation hard-coded intervals, etc. proof-of-concept @ point.

the data i'm analyzing http response-time data of form [date, response-time] , have csv file 18512 records in it. in summary band, have 3 items:

1. a text field dumping $v{report_count} (it reports 18512 in ireport's report preview)
2. a time series showing data points [date, response-time]
3. a category plot containing data points in single series [category=$f{date}, value=$f{response_time}]

i decided straightforward way build histogram use category plot because had right structure final histogram chart.

when chartcustomizer runs, dumps out kinds of information data set, including size. strangely, size 10252: it's missing 8000 data points. can't understand why category plot have fewer data points whole data set.

any ideas?

answering own question in case others run across foolish user error.

the problem categorydataset allows 1 data point per "category", , in case, "category" java.util.date captured web server log. apparently, half of dates duplicates , part of data set overwrote other half, leaving subset of data.

that should have been totally obvious me @ outset, because how category dataset works.

anyhow, changing category plot series's "category expression" $f{date} $v{report_count} gave each datum unique category makes work.