# Bar (OHLC) Chart A bar chart renders each OHLC interval as a vertical range bar with a short tick on the left for the open and a short tick on the right for the close. Use it when you want the readability of OHLC data but prefer a thinner, less ink-heavy rendering than candlesticks. It works well for very dense intraday charts, and when you plan to layer markers on top. Like candlesticks, bars are color-coded by direction: an up bar has the close above the open, a down bar has the close below the open. Because the body is just two ticks instead of a filled rectangle, you can fit many more bars in the same horizontal space. ## What are OHLC bar charts useful for? - **Dense intraday charts**: Bars take less horizontal pixel space than candles, so a 1-minute chart over a full session stays readable. - **Overlays and annotations**: A thinner price track leaves room for markers, price lines, and secondary series without visual conflict. - **Western technical analysis**: Many classical Western (vs. Japanese) chart conventions assume OHLC bars and read them more naturally than candles. - **Volatility scans**: Long vertical bars with ticks close together flag wide-range, indecisive periods. ## Examples ### A basic bar chart `tvl.bar` consumes the same OHLC table layout as `tvl.candlestick`. The `tvl.data.ohlc()` helper already has the canonical column names so the call is a one-liner. ```python order=bar,data import deephaven.plot.tradingview_lightweight as tvl data = tvl.data.ohlc() bar = tvl.bar(data) ``` Each row in `data` becomes one vertical bar with an open tick on the left and a close tick on the right. When `up_color` / `down_color` are not provided, the chart pulls them from the active Deephaven theme palette so the same code reads correctly in both light and dark themes. ### Map non-default OHLC column names When your table uses different column names (say `Ts`/`O`/`H`/`L`/`C` from a custom upstream join), pass them as kwargs. The chart only reads the columns you point at. ```python order=bar,data import deephaven.plot.tradingview_lightweight as tvl data = tvl.data.ohlc().rename_columns(["Ts=Timestamp", "O=Open", "H=High", "L=Low", "C=Close"]) bar = tvl.bar( data, timestamp="Ts", open="O", high="H", low="L", close="C", ) ``` ### Customize up and down colors `up_color` and `down_color` set the bar color for up and down intervals. The bar (range line plus open/close ticks) inherits a single color per bar, unlike candlesticks where bodies and borders can diverge. ```python order=bar,data import deephaven.plot.tradingview_lightweight as tvl data = tvl.data.ohlc() bar = tvl.bar( data, up_color="seafoam-800", down_color="magenta-600", ) ``` Both `up_color` and `down_color` accept a Deephaven theme color (e.g. `"seafoam-800"`, `"accent-300"`), a hex code (`"#26a69a"`), a named CSS color (`"crimson"`), or an `rgb()`/`rgba()` string for transparency. Theme colors adapt automatically when the user switches themes; hardcoded values do not. Leave them unset to inherit the active theme’s palette. ### Set a chart title `title` is the series legend label. Visible on hover and in the legend area. Use it whenever the chart will be embedded next to other content where the column names are not self-explanatory. ```python order=bar,data import deephaven.plot.tradingview_lightweight as tvl data = tvl.data.ohlc() bar = tvl.bar(data, title="ES futures, 1m bars") ``` The legend now reads “ES futures, 1m bars”. ### Server-side autobinning Hand the chart a large OHLC table and TVL automatically aggregates it server-side into a viewport-friendly number of buckets. Override the bucket count or width via `bin_count` / `bin_width`, or set `auto_bin=False` to bypass it entirely for small tables. ```python order=bar,data import deephaven.plot.tradingview_lightweight as tvl data = tvl.data.ohlc() bar = tvl.bar(data, auto_bin=True, bin_width="P7D") ``` See [autobin](autobin.md) for the full autobin surface: ISO-8601 duration grammar, when each `auto_bin` value is the right pick, and how the path interacts with the downsampler. ### Time-proportional layout with `continuous` By default (`continuous=True`) bars are laid out proportionally in time. Unlike the [histogram](histogram.md#continuous-bars), the open/close ticks are **not** drawn end-to-end — each bar keeps the classic proportions, and the ticks of adjacent bars never touch — but sections of data separated by a time hole (a market close, a halted feed, missing rows) are separated by a proportional open gap. On data with no holes, `continuous=True` and `continuous=False` look the same. Set `continuous=False` to restore the plain ordinal layout, which collapses any time hole to a single bar-width step. ```python order=bar,data import deephaven.plot.tradingview_lightweight as tvl data = tvl.data.ohlc() bar = tvl.bar(data, continuous=False) ``` ### Thin bars and hidden open ticks Two bar-specific styling options trim the visual weight of each bar. `thin_bars=True` renders each bar with a narrower body, which is useful on very dense intraday charts; `open_visible=False` hides the short left “open” tick so each bar shows only the range line plus the right “close” tick, a cleaner look when the open price is not the focus. ```python order=bar,data import deephaven.plot.tradingview_lightweight as tvl data = tvl.data.ohlc() bar = tvl.bar( data, thin_bars=True, open_visible=False, ) ``` The bars are now thinner and the left-side open tick is gone. ## API Reference Bar series render each bucket as a vertical line with small open/close ticks; contrast with candlestick_series() which fills the body. Same auto-bin behavior as candlestick. **Returns:** `TvlChart` A chart wrapping a single bar series.