Prevent element-wise string comparison

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Merge pull request pyqtgraph#921 from 2xB/patch-9

Prevent element-wise string comparison
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# `_updateMaxTextSize` to reduce text size when no longer needed
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# Currently `_updateMaxTextSize ` will increase the current space required for axis labels, if necessary, but not decrease it when the extra space is no longer needed. The proposed change will release no longer needed space again.

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# Clipping: don't assume that x-values have uniform spacing
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# Do not assume that x-values have uniform spacing -- this can cause problems especially with large datasets and non-uniform spacing (e.g., time-dependent readings from an instrument).
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# Use `np.searchsorted` instead to find the first and last data index in the view range. This only assumes that x-values are in ascending order. This prevents potentially too strong clipping.

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# draw path all around curve filling if enabled

# This is the 1st commit message:

Merge pull request pyqtgraph#921 from 2xB/patch-9

Prevent element-wise string comparison
# The commit message #2 will be skipped:

# `_updateMaxTextSize` to reduce text size when no longer needed
#
# Currently `_updateMaxTextSize ` will increase the current space required for axis labels, if necessary, but not decrease it when the extra space is no longer needed. The proposed change will release no longer needed space again.

# The commit message #3 will be skipped:

# Clipping: don't assume that x-values have uniform spacing
#
# Do not assume that x-values have uniform spacing -- this can cause problems especially with large datasets and non-uniform spacing (e.g., time-dependent readings from an instrument).
# 
# Use `np.searchsorted` instead to find the first and last data index in the view range. This only assumes that x-values are in ascending order. This prevents potentially too strong clipping.

# The commit message #4 will be skipped:

# draw path all around curve filling if enabled

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# allow different color for tick labels
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# created new `textPen` and `setTextPen` methods

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# Revert "draw path all around curve filling if enabled"
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# This reverts commit d5dd912.

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# Revert "Clipping: don't assume that x-values have uniform spacing"
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# This reverts commit 365c13f.

# The commit message pyqtgraph#8 will be skipped:

# Revert "`_updateMaxTextSize` to reduce text size when no longer needed"
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# This reverts commit 1ea6461.